Dr. Natalie Crawford: Egg counts crash after 32, plan now

Dr. Natalie Crawford 0:00 People are waiting longer to get pregnant, but if we imagine that there is a vault of your eggs, by the time you're born, you have one to two million. In your reproductive years, 300,000. This means if you and your partner wait till 35, your chances of getting pregnant are going to be approximately ...

Steven Bartlett 0:16 I feel like I better get a move on.

Dr. Natalie Crawford 0:17 But there are things that we can do to improve your reproduction, and this is information that nobody talks about.

Steven Bartlett 0:23 So let's get into it.

Dr. Natalie Crawford 0:24 Let's do it. Dr. Natalie Crawford is a double-certified practicing fertility doctor. Helping people to optimize their lifestyle to improve fertility. Rates of infertility are increasing. One out of every eight women would have infertility, and now it's one out of every five, and there's multiple factors that are contributing, including irregular or lack of having a period. There's more autoimmune disease, obesity, chronic stress. People are waiting. But at 40, your chance of miscarriage is 50%, and suddenly, you're left behind, and I know that because I had four pregnancy losses, and... I'm gonna cry now.

Steven Bartlett 1:02 Lots of people will be struggling with a variety of the things that you've talked about. What would you tell them?

Dr. Natalie Crawford 1:06 You can't control everything, but you should be able to control the factors you can.

Steven Bartlett 1:10 So what would my daily habits look like?

Dr. Natalie Crawford 1:12 I love that question. So-

Steven Bartlett 1:14 What about our misconceptions around how to increase our odds of getting pregnant?

Dr. Natalie Crawford 1:17 Yes. There's so many myths.

Steven Bartlett 1:18 If a female orgasms, does that increase the chance of fertility?

Dr. Natalie Crawford 1:22 This is super interesting.

Steven Bartlett 1:23 And then what is the number one thing that people don't do that impacts their reproductive system?

Dr. Natalie Crawford 1:29 It seems so straightforward. It's not a pill that you take or major change of behavior. It is simply...

Steven Bartlett 1:36 We've just hit six million subscribers on The Diary of a CEO. Um, so me and my team would like to do something we've never done before as a little thank you, and we're calling it The Diary of a CEO Subscriber Raffle, and here is how it works. Every episode this month, we're going to pick three current subscribers at random, and we'll send one of you a 1,000 pound voucher, one of you tickets to come and watch The Diary of a CEO behind the scenes live with our team, and one of you will have a 10-minute phone call with me to discuss whatever you want to talk about. If you're a subscriber, you're in the raffle. Thank you from the bottom of my heart for allowing me to do something that me and my team love doing so much. It is the greatest honor of my lifetime, and I hope it, I hope it continues, uh, off into the future. Let's get to the episode. Natalie, who are you, and what is the mission that you're on?

Dr. Natalie Crawford 2:25 Hi, Steven. I am a fertility doctor, which means that I help people grow their family or plan for their family, no matter what that looks like. But my mission started because early in my career, I realized I was seeing people when they were already behind the game. They didn't have the basic knowledge about how their body worked, their hormones, their reproductive system, and I had to bring them up to speed, and every time, somebody said, "I wish I'd known this earlier. I can't believe I wasn't taught this. Why isn't this the stuff that we're taught, because I might have made different decisions earlier in my life." And that was a pivotal moment for me about eight years ago, when I started wondering if I could reach people earlier in their journey, before they had infertility, before they were in my office, if maybe that could change the trajectory of their course, if they could be more empowered with that education to make the decisions that are right for them, versus just letting time pass, which ultimately makes some decisions for people.

Steven Bartlett 3:27 And when we talk about getting started earlier and thinking about this earlier, when we, we, we f- hear the topic of fertility, I think most of us think it's something that people over the age of 35 need to start worrying about, or, you know, once we get up until close to our 40s, then we need to start thinking about our fertility more consciously. But what you're saying is, is that fertility or infertility starts much earlier in the decisions we make.

Dr. Natalie Crawford 3:51 100%. If we view fertility as the ability to get pregnant, and infertility is a disease. In the World Health Organization, the CDC, everybody defines infertility as a disease, the inability to get pregnant. So then we can view fertility as more of the health, the wellness state, and just like we're trying to prevent disease in other aspects when it comes to cancer, Alzheimer's, many other diseases, we need to be approaching our fertility as a preventative action, taking steps to make sure that if having kids is one of your life goals, you're not making choices that is going to make that impossible or extremely difficult when you get to that stage.

Steven Bartlett 4:31 And what is the sort of macro social cultural backdrop to this? Because the conversation around fertility and infertility, to me, and this might just be a sort of perspective bias, seems to have suddenly increased over the last couple of years, um, and I don't know whether that's just because I'm in that age range now where my friends are having the conversations or that I think socially, we're starting to think more about it, because there is some pretty alarming data that's emerged around people struggling more than ever to conceive children, because there's like social factors at play.

Dr. Natalie Crawford 5:02 Exactly.

Steven Bartlett 5:03 What are, what is that social backdrop?

Dr. Natalie Crawford 5:05 So it's very interesting when you try to put the whole picture together. One, because we are more aware of fertility. We have social media. People are sharing their stories. 20 years ago, you didn't know somebody might have infertility or be struggling. Similarly, there was less access to reproductive technology. Things like egg freezing didn't exist. You couldn't do IVF unless you traveled to a city that had a big enough program. And so when there were limited ways to treat something, there was less access to get into care to even be evaluated. So one, we do have people more aware about their fertility, getting diagnosed earlier and easier, finding out problems sooner, and some of that is... Well, I think all of that's wonderful. Socially, yes, ri-rates of infertility are increasing. We used to say one out of every eight women would have infertility, and now in the US, it's one out of every five who's just trying to conceive for the first time will have infertility. So that's a huge increase. It stays even when you...... confound studies for age. So the number one thing everybody says is, "Well, people are waiting longer to get pregnant," which is absolutely true. I think only 5% of people started their family over age 30 back in the '70s, and now it's 25 to 30%. So we see a huge increase in the number of people who are waiting to start their family. I did, you are. Especially as women are being empowered to chase other dreams, go to professional school, they're delaying entry into child-bearing. So part of this is that people are waiting later, diseases develop later, but then also as a society, people are less healthy. We see more obesity, we see more diabetes, we see more environmental toxins than we ever have. So I really think this is something where there are multiple factors that are all contributing to this alarming rise of infertility that we're seeing.

Steven Bartlett 7:00 And are we having less sex than we used to?

Dr. Natalie Crawford 7:04 I think people are having less sex, yes, especially as they age. In the reproductive age range, it depends. People, when they get married, tend to be having less sex, but interestingly, there's been a really good study looking at marijuana, so we'll use it for example. People who smoke marijuana tend to get pregnant less even though they're having more sex than people who don't. So when you say this group's not smoking marijuana and they're getting pregnant even though they're having less sex than this other group, it's showing us that it's not just timing or not having intercourse. There really are other factors at play that are very socially acceptable that are influencing the ability to get pregnant.

Steven Bartlett 7:47 I was reading through some research earlier about fertility and the sort of global trends, and I read this one stat that said the global fertility rate has decreased from 4.84 live births per woman in 1950 to 2.23 in 2021, and it is expected to drop to 1.59 births per woman by 2100, which means that we're... there's clearly a traject- I mean, if this is true, then there's a trajectory south-

Dr. Natalie Crawford 8:16 To having less kids.

Steven Bartlett 8:17 Yeah. And I-

Dr. Natalie Crawford 8:18 In the US, it's 1.3 is the average right now-

Steven Bartlett 8:20 Really?

Dr. Natalie Crawford 8:20 ... for a single woman. Or, uh, one person will have, on average, 1.3 children. That's very alarming when you start thinking about is that number just people are waiting, or what about all the people who just can't get pregnant? And I see those people in my office over and over and over again, that are n- not able to get pregnant even if they're starting young. So I think that we really have two factors going into that statistic you saw. When it comes to sperm, you know, a study came out last year looking at sperm counts, and they've decreased 50% in 50 years. What's most alarming about the sperm count decrease in men is that in the past 10 years, it's decreased at double the rate than it did the 40 years prior. So when we start looking at more recently, the rate of decline is accelerating, and that's got to be the world around us.

Steven Bartlett 9:14 And you, in 2020, founded the Fora Fertility Clinic, which is based over in Austin. How many couples, women, people have you seen since you've opened that clinic, and what is the typical sort of case study of why someone will come to you in that clinic? What are they searching for? What are they struggling with?

Dr. Natalie Crawford 9:32 I love that question. So yes, I started Fora in 2020 with my partner, Amanda Skillern. She and I have been practicing for quite a while at this time and realized that there wasn't an approach, at least in Austin, for personalized care. Because of that, probably the number one type of patient that we see is coming in who's already had lack of success somewhere else. Meaning, went to a clinic, has been trying... The average patient is going to be over age 36, has been trying for one to two years, learned about their cycles, tracking their cycles, relatively normal evaluation, trying to do IVF, and now is not getting the result they wanted. What I find the hardest thing for people is the isolation. You're suddenly being left behind in your friend and your peer group when you're trying to have a child and those in your world have succeeded, and suddenly you're left behind. And the stress and the isolation that causes really makes the entire process so much harder than many other medical diagnosis that somebody might get.

Steven Bartlett 10:38 Can you give me some more color on how that feels? Because you, you know how that feels.

Dr. Natalie Crawford 10:43 I do know how that feels. So I had four pregnancy losses before I had my two children, and this was a long time ago, and I was in the middle of training, so I was a resident and a fellow. Definitely was not taking care of myself very well because that was the lifestyle of a doctor in training, and I didn't tell anybody I was pregnant, minus my husband, for the first three pregnancies. Because people weren't sharing about their pregnancies, I had this idea, "I need to wait till I'm in the safe zone, I'm out of that first trimester." And so when I started losing those pregnancies, nobody knew I was pregnant, so it was so hard to come and tell somebody that I was losing the pregnancy when I hadn't even opened that door to trust them with the first piece of information. It was very hard to come in with that subsequent request for support or help, and I just felt like that wasn't what people were sharing or talking about. My fourth pregnancy loss was an ectopic pregnancy, which is a tubal pregnancy. So this is a pregnancy that implants in the fallopian tube instead of in the uterus. Those pregnancies cannot grow. The fallopian tube doesn't have the blood supply to support a placenta, and the fallopian tube can rupture, and it can become a surgical emergency and be very scary. That was diagnosed for me when my husband was off in...... a bachelor trip in Las Vegas, and I had to receive a medication in order to try to stop the pregnancy from growing, but there was still a risk of the tube rupturing, and I w- was forced to call friends, have somebody come with me, be with me. And sharing it, there was so much support given that I realized that was such a mistake of mine. Not that you need to post every pregnancy announcement on the internet or tell everybody at your job, but there are people in your life who want to support you, and they can't show up if you don't let them know what's going on. And that's one of the things that I tell my patients is that, give the people in your world the opportunity to show up for you. Tell the people who are asking, who you turn to in other times of crisis, tell them that you're struggling with this. Let them show up and support you because most of the time, people will. They care about you, and that is going to lessen the burden. Because that isolating piece, the doubt and the fear, especially if you're a goal-oriented person. I have set so many goals, and I'm gonna do this, and here is my path to do it. So to feel like I was failing at becoming a mother when I didn't fail at anything, and now my body was failing me, felt so shameful, so much guilt, and I had nobody to share that with or to help alleviate that burden from me.

Steven Bartlett 13:36 You used the word guilt there. There's, um, a complex set of emotions that I've had described when someone finds out that their, their pregnancy or even their sort of, their sexual organs more broadly are struggling with something, and I've got lots of friends that have been diagnosed with a variety of different conditions, um, in that, in that sort of, with their sort of sexual health, and i- it- you almost observe a feeling that they can often feel like they are broken in some way, like they're not, they're not, you know, working, they're like a broken person, and I- I- I say that to try and highlight the fact that those, that's, there's so many people going through that exact same thing and that all of these conditions are very, um, a lot of people are struggling in silence with that feeling of in- of inadequacy.

Dr. Natalie Crawford 14:24 You're so right. There's so much stigma to infertility. There's so much misinformation and uncertainty when it comes to reproductive health together that makes it difficult for people to talk about or ask questions, and when you feel like one of the things that you always thought was certain about your future, if you were a child and you envisioned your life 30 years from there, something, if you envisioned having children and suddenly you're faced with the potential reality that that might not happen or it might not happen without intervention, th- that really crashes down a piece of your own identity and, and who you saw yourself to be, who you wanted to be, and trying to struggle with that r- true identity crisis at that moment really brings out so many emotions. It's what so many of the people who sit across from me every day say, "I just, I don't feel like myself. I feel like I'm stuck while everybody else is moving on because I'm broken. My body is failing me." It's so hard to watch somebody go through it, and even if I can't get everybody pregnant or control the outcome, the thing that I always say is that, at a minimum, you need to understand how your body works. At a minimum, you can know that you're making the choices that are right for you. You can feel good that you did everything that you could and that there wasn't education you needed or choices you would have made looking back in the rearview mirror, and even when somebody's deep in the midst of failed IVF cycles or sitting across from me, I say the same thing. That's, that's our minimum. You deserve to understand why we're making the choices so that this can be a process where you can advocate for your care and we can collaboratively do everything we can to try to achieve this goal for you.

Steven Bartlett 16:15 I had, um, got a good friend who's just, um, 'cause obviously I'm at that age now where my friendship circle are starting to go and get fertility tests done and such and they're trying for kids. Many of them are, have been very successful, but I've got one particular friend who has been trying for some time. They're struggling, so they went and got the, the tests done, and it turns out that one of them in that relationship has some, has some issues which are complicating their chances of getting pregnant, and when I heard that, yeah, God, I can't imagine how that person feels in that relationship because it'll m- k- I can imagine in your head how you can start to overthink and you can feel that word again, that word guilt towards your partner, and you can start thinking, "Oh my God, this person's gonna leave me because I can't give them what they want," and all of that sort of complex, those complex, slightly irrational but completely understandable thoughts.

Dr. Natalie Crawford 17:06 The relationship aspect is so hard, even going through it myself, because my husband wanted to support me, and of course he did, but I felt like I was the one failing, not him, right? I'm the one who's not bringing my A game to the table. This is a me problem, and even though it's an us problem, it felt like a me problem to the point where I really try to level the playing field to all of my patients, at least when I see them, and say, "It's the two of you. You're a team. This is a team. It doesn't matter whose diagnosis comes back as what. We are trying to get us pregnant," and really reframe everything that way. I have a patient story from the past who had been going through infertility, been going through IVF because she found out she was running out of eggs early, and she had taken a lot of blame for not freezing her eggs earlier, for waiting longer, and going through IVF, her husband...... turns out his sperm wasn't functioning the way that it should, and we didn't know that until you fertilized the eggs with it and really see how embryos grow in the lab. And she said to me at our follow-up visit, even though the outcome of that cycle was devastating, to have no embryos develop because they found this sperm issue, it improved their marriage so much, because for the first time, her partner and her, they felt like they were on even playing field, that they were both part of the reason they were in this situation. And whether it was imposed by him or not, she had carried that guilt, that shame, that broken feeling alone, like it was

Dr. Natalie Crawford 18:49 just her.

Steven Bartlett 18:49 So let's get into it, then.

Dr. Natalie Crawford 18:51 Let's do it. Yep.

Steven Bartlett 18:51 Let's talk about fertility. Where do we need to start? I was gonna assume where I need to start here, but I'm an absolute, um, muggle and idiot as it relates to fertility and female and male reproductive health. So where do we start if we wanna understand fertility?

Dr. Natalie Crawford 19:06 I always like to start with the ovary and understanding the difference in eggs and sperm. So we'll do sperm first, then we'll do eggs.

Steven Bartlett 19:13 Okay.

Dr. Natalie Crawford 19:14 Do you know how many sperm you make in a day?

Steven Bartlett 19:16 Do I know ... Uh.

Dr. Natalie Crawford 19:18 How about how many you make in a second?

Steven Bartlett 19:23 No. I have no idea.

Dr. Natalie Crawford 19:25 The average man makes 200 to 300 million sperm in a day and 1,500 sperm a second. So men-

Steven Bartlett 19:32 1,500 sperm a second?

Dr. Natalie Crawford 19:33 1,500 a second. You're just like ... So, men and their testes have germ cells, meaning they can just produce brand-new sperm at very high rates every single day, and in the ovary, for women, it's so different, because you are born with all the eggs you're ever going to have, and you run out of them over time. And this means that, one, the number of eggs you have remaining is a part of the picture, and two, your eggs sit inside your body, and they absorb the wear and the tear and the world around you your whole life. Where your sperm lifespan is 90 days. Takes 72 days for sperm to grow across the testicle and then 18 days to get out the ejaculatory system, so you have three months. So you could change your life and change your sperm counts in three months.

Steven Bartlett 20:24 Why does it take 18 days?

Dr. Natalie Crawford 20:26 Yeah.

Steven Bartlett 20:26 I thought if ... In my little idiot head, I thought that I make my sperm, okay, today, and then if I ejaculate, that's the sperm out.

Dr. Natalie Crawford 20:35 No. Yeah, those sperm, those sperm were made a couple months ago.

Steven Bartlett 20:37 Really?

Dr. Natalie Crawford 20:37 Yeah. They're, like, in storage lockers so that you have some for every day, so they kind of get-

Steven Bartlett 20:42 What?

Dr. Natalie Crawford 20:42 ... put in line so that you can send them out at that right time period.

Steven Bartlett 20:47 Okay. So, but if you ejaculate multiple times, eventually you can't keep producing more, but-

Dr. Natalie Crawford 20:54 So let's imagine that you have lockers, and we'll just pretend-

Steven Bartlett 20:58 Yeah.

Dr. Natalie Crawford 20:58 ... that there's 200 million sperm in each one.

Steven Bartlett 21:01 Okay.

Dr. Natalie Crawford 21:01 If you ejaculate every single day, you're ejaculating 200 million sperm each time. Now, if you're saving up for a couple days, you're gonna ejaculate 400 million, and now if you've waited three days, 600 million. The catch here is sperm are so fragile. They're so fragile. They like to die. They get-

Steven Bartlett 21:20 Tadpoles.

Dr. Natalie Crawford 21:20 Oh, those little tadpoles. So if you wait too long, you're just gonna have a bunch of dead guys, and then they're going to impair the ability of the better sperm to even function. And I use the analogy of imagining that this is a highway-

Steven Bartlett 21:33 Yeah.

Dr. Natalie Crawford 21:33 ... and the dead sperm are stalled cars all over the freeway. Even if your sperm count's normal, if you're having very long abstinence periods in between your intercourse times, you're going to have a sample that has so much debris and dead sperm in it that it's gonna make it hard for the good guys to do their job.

Steven Bartlett 21:51 Okay, so there is ... So you do need to keep ejaculating to remain-

Dr. Natalie Crawford 21:53 You do.

Steven Bartlett 21:53 ... to optimize your fertility, your chances of fertilizing an egg?

Dr. Natalie Crawford 21:56 Yes.

Steven Bartlett 21:57 Oh, I didn't know that. And w- how often? Do you know?

Dr. Natalie Crawford 22:00 I always say it's gonna ... There's a fine balance here. Somewhere between every day to every three to four days is going to be the best, whether that is ejaculation in any form, what- whatever suits your fancy. We see that longer than seven days for the most, for most people will severely increase the amount of debris that you see and the proportion of the ejaculate that is dead sperm.

Steven Bartlett 22:26 Super interesting. So let's go ... We'll stay at the, the foundations. We're talking about s- sperm and eggs. So is that, sperm, covered off? Is everything-

Dr. Natalie Crawford 22:35 So sperm.

Steven Bartlett 22:35 Okay. And sperm counts have, as you said earlier, have been reducing over the last 50 years by 50%, which is hor- horrifying. Um, why? Is there something in particular in our environment that's causing that?

Dr. Natalie Crawford 22:48 It's all the things, and some of them are changeable, and some of them are not. So we have to view the world as it is. Certainly, we see we've got more men who are unhealthy, who are overweight, who have other medical comorbidities that are also impacting their ability to make sperm. Like, if you have high cholesterol, if you have diabetes, some of those things are going to impact your overall health and the production of sperm. So this goes for sperm or egg. The hormone axis from the brain to your gonad, your gonads are either your testes or your ovaries, your brain is constantly interpreting signals from your whole body and is trying to determine, "Can Steven have a kid right now?" And if you become very stressed ... Now, back in the day, what was that? There was a bear attacking you. There was a famine, so you had no food. There was a plague going around. Then it'd say, "This is not a good time to have a child right now."

Steven Bartlett 23:43 Because?

Dr. Natalie Crawford 23:44 Because you can't support your own body, or the world around you. Your adrenal glands are making cortisol because it's so stressful, or your calorie intake went down, so your brain says, "This is too difficult. I am going to shut off the system to make reproductive hormones." And that happens in both men, and it can happen in women. So the brain is constantly interpreting the world around you and then sending out signals to make-... eggs or sperm, like to make eggs grow, or to be making sperm, and the hormones that are associated with them, so estrogen and progesterone for women and testosterone for men. And so one, we have anything that interferes with this pathway, people are more ill. There's more autoimmune disease, more inflammation. There's more stress, chronic stress. There's more obesity. But then we also see the environmental impact as well. So certainly, there's so many toxins in our world, from the foods we eat, from the air we breathe, from the type of, you know, kitchenware that we use, what we put in and on our body. All of it makes a little bit of a difference, and we know some people, if you live in an area with high pollution, you're going to have lower sperm counts and a reduced fertility rate. But that might not be something you can change because that's where you live. But it might be even more important for that person to understand it and then wanna not also smoke marijuana or drink out of plastics or do other things that might be adding to that burden.

Steven Bartlett 25:23 So smoking marijuana and smoking cigarettes are no-nos, if I-

Dr. Natalie Crawford 25:27 Absolute no-nos. So, s- I think cigarettes, most people are pretty aware cigarettes are pretty bad for your health. If we talk about reproductive health in general, cigarette smoking for- for women and your eggs are going to decrease your egg count, your egg quality, and the rate of miscarriage.

Steven Bartlett 25:44 Significantly?

Dr. Natalie Crawford 25:45 Significantly. For men, what we see is it decreases your sperm count, your sperm motility, and the quality, the shape of the sperm, also increasing miscarriage. Marijuana does this as well. If you smoke marijuana, even if your partner does not and is never around you when you're using it, she has a higher chance of a miscarriage just because you're smoking marijuana.

Steven Bartlett 26:10 How?

Dr. Natalie Crawford 26:11 Because of DNA damage inside the sperm's head.

Steven Bartlett 26:13 Ah, okay. I'm giving her bad sperm.

Dr. Natalie Crawford 26:15 You're giving her bad sperm.

Steven Bartlett 26:16 What about vaping?

Dr. Natalie Crawford 26:17 We don't know as much about vaping, but it appears in all the preliminary studies to be similarly very bad, that what is in, um, what you're breathing with vaping might even be more harmful than cigarettes potentially.

Steven Bartlett 26:32 What about phones and laptops?

Dr. Natalie Crawford 26:35 Ooh, I love this one. Okay, so that's a great question, and people ask about it. Two ways to look at it. There was a study that was published last year that actually looked at this, and we'll talk about just having your phone, using your phone, and then location of the phone. In the study, what they looked at is phone usage from 2005 to 2018. So we have to remember in 2005, phones were different. It wasn't quite the same, but they had a much higher, uh, radiation emitted from them. So, modern phones actually emit much less radiation. So even though we keep them on our person, they're ultimately safer than what we saw as origin phones from 2005 to 2010. In this study that they looked at, the number of times that you used your phone, which is wild to us 'cause we use our phone constantly now. But the number of times you used your phone, the more you used it, the less sperm you made. Okay? However, that was most impactful for the early generation phones from 2005 to 2010. So when they stratified and looked at some of the phones we have now, we're not seeing that same impact, and I think that is because there's less radiation, and also, everybody uses their phone more than 20 times per day, right? You're using it all the time. Location didn't matter. There was no difference of location. Whether you kept your phone in your pocket, your back pocket, the counter, off your body, there was no difference. So I think that helps us understand some of the radiation aspect of the phone and if that is impacting sperm. Heat of the testicle is, of course, something very, very different. I do think you talked to Rena about this. So when it comes to the testicles, they live outside your body for a reason. We know that men who have an undescended testicle, even if it's surgically removed-

Steven Bartlett 28:26 Sorry, what's an undescended testicle?

Dr. Natalie Crawford 28:27 Oh, you can be born with one of your testicles in your abdomen instead of in your scrotum.

Steven Bartlett 28:31 Uh-huh.

Dr. Natalie Crawford 28:32 And that's usually surgically corrected before the age of one, because if it stays internally, the heat of the body is too hot, and it destroys the cells, the inability to make sperm, inability to make testosterone. So, the testicle is outside the body in the scrotum so that it can be kept at a lower body temperature. We know that things that increase the temperature of the scrotum do impact sperm production and testosterone production. Testosterone and sperm are made together, so one thing is gonna influence one, it will influence the other. This is sauna use every day, hot tub use every day, laptop in your lap. If you are putting your phone exactly by your scrotum every single day, then it might be having an impact if it's heating up and it's the heat that's causing the problem, not the radiation that's being emitted from it. So we always are asking, if I see somebody for infertility, I'm going through any behaviors that are significantly increasing the temperature of the scrotum to see if that is a modifiable factor.

Steven Bartlett 29:40 What about hot baths, if we're having lots of hot baths?

Dr. Natalie Crawford 29:43 If it's daily and you sit in there for, you know, more than 15 minutes, then I would cut that down to not be daily. I see this a lot in Austin from people who love to cycle. So they're on a bike. They're outside. They wanna go ride for two to three hours at a time, numerous times a week. That's a lot of heat contained right to the scrotum area, and we often see m- significantly lower sperm counts in men who cycle at that intense level. Interesting, right?

Steven Bartlett 30:13 Very interesting.

Dr. Natalie Crawford 30:15 (laughs)

Steven Bartlett 30:16 Um, what about TRT? You s- talked about the, the correlation there and the relationship between-... sperm and, um, testosterone levels. If men start taking TRT, which is hormone replacement therapies, testosterone replacement therapy, um, does that impact the quality of my sperm and my chances of fertility?

Dr. Natalie Crawford 30:33 Stephen, at least one time per week, I will see a couple who comes into my office who has been trying to get pregnant, and the male partner went to a hormone clinic, a men's health, and he was put on TRT for libido or fatigue or something. And essentially, that is male birth control, because taking testosterone yourself is telling your brain that there is testosterone present, because naturally, testosterone is made as sperm is made. If your brain thinks there's a lot of testosterone, it says, "Hey, we don't need to make much more. We're doing really good." So the hormones from your brain stop being sent out and no longer tell your testicle to make any more testosterone or any more sperm. So TRT use makes men azoospermic, meaning having no sperm in the ejaculate. You still have an ejaculate, it looks the same to you, but when we go look at it under the microscope, there's no sperm in it. Sometimes that is irreversible. The longer you've taken TRT for, there's a chance that I might not be able to get sperm to return to your ejaculate. It might be permanent.

Steven Bartlett 31:45 Let's talk about eggs.

Dr. Natalie Crawford 31:47 Let's talk about eggs.

Steven Bartlett 31:49 You have this, um, wonderful example where, I guess, it's a bit of an analogy called the vault.

Dr. Natalie Crawford 31:53 Yes.

Steven Bartlett 31:54 I've got, um, some marbles over here in a jar, which I thought would, um, help us to visualize this idea of a vault. So I've put about, I don't know, there looks like there's about... How many marbles do you reckon are in there? If you, uh, get it right, you win the whole lot.

Dr. Natalie Crawford 32:07 Uh, 200 marbles.

Steven Bartlett 32:09 200. I'm gonna say we'll count after, um-

Dr. Natalie Crawford 32:13 Well, now you're counting. That's different than guessing.

Steven Bartlett 32:15 No, no, no. No. I'm not, I'm not...

Dr. Natalie Crawford 32:16 (laughs) .

Steven Bartlett 32:16 Just go on, have a guess how many marbles are in there. We'll count after, we'll see who's right.

Dr. Natalie Crawford 32:19 Okay, I said 200.

Steven Bartlett 32:20 Okay. Anyone in the comment section below also you can, you guys can also guess. Don't cheat. Don't sk- skip to the end. I think there's about...

Dr. Natalie Crawford 32:28 He is counting. That is not called guessing.

Steven Bartlett 32:30 Well, you're allowed... I can't count them all, can I? 'Cause I can't see them all. Seven times 72.

Dr. Natalie Crawford 32:33 Nobody else can see them all and count them.

Steven Bartlett 32:35 140.

Dr. Natalie Crawford 32:35 Okay.

Steven Bartlett 32:36 This is the analogy. I'm gonna pass them over to you. Um, I'd love you to use this as an a- an, uh, a visual aid to explain to me this idea of the vault as a, as a way to understand how many eggs women have and how that changes over the course of our lives.

Dr. Natalie Crawford 32:49 Love it. All right. So I like to think about the ovary as inside your ovary, if we can imagine that there is a vault of your eggs. So that is what this jar is representing. So again, in contrast, in men, testes are making brand new sperm every single day. In women, when you are a five-month baby inside your mother's womb, you have the most eggs you're ever going to have. You have six to seven million eggs. By the time you're born, you have one to two million. By the time you start puberty, you have half a million. Your reproductive years, you're going to start with about 300,000. And by the time you go into menopause, you'll have less than 1,000 left. So you still have a few eggs left. Women only ovulate about 400 to 500 eggs over the course of their lifetime. So if you're born with one to two million and you only ovulate 400 to 500, that seems like confusing math. So the way that I think about it is that every single month, you are losing eggs from this vault. And what is happening is that the eggs are coming out in proportion to how many are inside. So when the vault is more full, more eggs come out that month, and when the vault is less full, less eggs come out. So if we can imagine one month, you're gonna have a group of eggs (marbles clattering) all come out of the vault. And so if this is our ovary, what we would imagine is that the vault sent out all of these small eggs, and each egg grows inside a follicle. The brain is going to send out follicle-stimulating hormone once you start puberty. So before puberty, all of these eggs are just going to die after that month is over. (marbles clattering) But once you've started puberty, FSH, so follicle-stimulating hormone from the brain will come and stimulate one of these eggs.

Steven Bartlett 34:39 Why only one?

Dr. Natalie Crawford 34:40 Because humans are not meant to have litters. You can only carry one child at a time in our uterus. So this is the protective mechanism by which humans don't have multiple children most of the time. So each egg grows inside what we call a small follicle. So the brain sends out follicle-stimulating hormone. This is one of the rare times where in medicine, hormones are named for what they do in women, not men, because you have FSH and LH too. FSH controls the production of sperm for you, and LH, the production of testosterone. But for women, FSH controls the stimulation of one follicle. S- so this follicle will grow and this one will ovulate, and the rest of them will die. So that's one of the 400 that I'm gonna lose. These just go away.

Steven Bartlett 35:25 I wanna make sure I understand this. So in the jar-

Dr. Natalie Crawford 35:28 Mm-hmm.

Steven Bartlett 35:28 ... is the vault that's inside the woman.

Dr. Natalie Crawford 35:30 Yep.

Steven Bartlett 35:31 Um, at every month-

Dr. Natalie Crawford 35:33 Month. This is what's available this month.

Steven Bartlett 35:35 Okay. She produces quite a few, like 30-

Dr. Natalie Crawford 35:37 When you're younger, yeah, 'cause there's more in my jar.

Steven Bartlett 35:39 Proportionately, there's like 20 or-

Dr. Natalie Crawford 35:41 Proportionately.

Steven Bartlett 35:41 Okay. There's 20 or 30, and they're proportionately to a jar that has 200. These numbers aren't obviously ratioed, but... And then one of them is basically selected-

Dr. Natalie Crawford 35:49 To ovulate.

Steven Bartlett 35:50 ... at random?

Dr. Natalie Crawford 35:51 At random.

Steven Bartlett 35:52 So again-

Dr. Natalie Crawford 35:53 It's one of the great mysteries, if we could control which one, because it doesn't have any more likelihood to be genetically normal or good just because it responds. So what is interesting when we think about this vault is, as we said, when we have less eggs, less are coming out every month. So you're gonna start to dump out less eggs. (marbles clattering) ... and the jar gets emptier.

Steven Bartlett 36:13 What age was I then, and what age am I now?

Dr. Natalie Crawford 36:15 So, we can say that you, you know, were 30 at one point, and now we're starting to get to about age 34 at this point.

Steven Bartlett 36:22 Okay.

Dr. Natalie Crawford 36:22 Okay? What starts to happen, just for numbers, so at age 30, you're gonna have about 20 eggs come out of the vault every month. One egg will ovulate, 19 will die, next month, another group. Okay? When you get to about 35, you're gonna have about 14 to 15. So still pretty close. When you get to 40, it'll be about eight to 10 per month. Forty-four, closer to three to four per month. So you start to see that after age 37 specifically, a more rapid decline in how many eggs are remaining, therefore less are coming out every month. This idea is really important for two reasons. One is that all women run out of eggs. When you run out of eggs, you are in ovarian failure, also known as menopause. Average age of menopause is 51 to 52. I've seen somebody have menopause at age 13. So s- I've seen primary amenorrhea, where somebody was born with ovaries that never made follicles. I've had women who had their periods and then they ran out of eggs in their 20s. So some people are on different pathways. Now, maybe they were born with less. Maybe something happened to them along the way to make them run out of them faster. So certain things can get in the vault and impact our ultimate egg count. So as we already said, smoking cigarettes, marijuana use, endometriosis, which we haven't touched on quite yet but we will, chemotherapy, environmental toxins. So certain things can get in here and make us run out of eggs faster. What's also important to understand is that the eggs that are out in one month are all the eggs we have to work with. So when we start talking about egg freezing or IVF, I can only get the eggs that have been sent out of the vault in that month to grow. I cannot tap into the vault. And this is why if you've had friends go through IVF or egg freezing and it sounds random, somebody got six eggs and somebody had 24, somebody had to do multiple cycles or months, sometimes in order to help somebody get enough eggs to have a normal embryo, what we have to do is multiple months. So the 10 eggs that are available this month, I'm going to get them all to grow, not just the one you were normally going to ovulate, take those eggs out of the body. And then next month when your body gives me another group of 10, I'm going to get them all to grow again, and take those eggs out of the body. That is ovarian stimulation for either egg freezing or IVF, trying to say, "Hey, in this month, I don't wanna let any of these eggs die, because I need more of them to get the job done, or we're running out of time and I'm trying to expedite your opportunity for conception." So women have this decline in the total number of eggs you're going to have. When you're 37, I think the number is that you have close to 20,000 eggs remaining. So what a huge drop from when you started puberty at half a million. So it's just going down so fast every single month. What is also happening is that because these- this vault inside our body, when you smoke the cigarettes, when you eat processed foods, when you get sick, if you have chronic inflammation, you're losing some, but the ones that are here at the bottom, they've been here the whole time. And so in addition to number of eggs, we have to talk about the quality of the eggs, because these eggs... down here at the bottom, once you get older, they've been sitting here a long time. And that means that their chromosomes inside of them are much more likely to be abnormal than normal. And that's really the rate-limiting step in people getting pregnant when they're older, not that my vault is more empty, not that I'm sending out less per month, but that the ones that have been sitting here have been sitting here longer. And they aren't as good. I- I use the analogy for the chromosomes. So if we imagine your eggs hold your chromosomes in perfect position so that they're ready to then go be fertilized by sperm, it is like having kindergartners stand in a line for 40 years. Somebody's gonna get out of line.

Steven Bartlett 40:48 Mm-hmm.

Dr. Natalie Crawford 40:48 And when that happens, that increases the rate of genetic abnormalities, and most of those do not fertilize, do not implant, or miscarry. At age 40, if you see a positive pregnancy test, your chance of miscarriage is 50%. Because they've been sitting here. Even if you're very healthy, just time and normal life impacts things. But there's choices you make that cause them to degrade faster, and there's things that you do that might be protective, and that is something that we don't ever talk about. We- when you're 35, your chance of miscarriage is 25%. So there's a huge change that happens between age 35 and age 40. When you're 35 and you start trying to get pregnant, so if you and your partner wait and you say, "Everything's good, we're gonna wait till we're 35," your chances of getting pregnant per month are going to be approximately 10 to 15% per month. That's not- not very high.

Steven Bartlett 41:50 It's not great.

Dr. Natalie Crawford 41:51 Not great. At 40, it's about 5% per month. So we've dropped dramatically in just seeing the positive test.

Steven Bartlett 41:58 Okay.

Dr. Natalie Crawford 41:58 And then if you see it, 50% are abnormal. So the odds that the body is gonna choose from the eggs that are sent out that one month when you're 40, the odds that-... your body's gonna choose one of the two eggs that is genetically normal, because six of them are abnormal, it's not very probable. So most months, your body's ovulating one that's not going to have the potential to become a live born baby.

Steven Bartlett 42:33 I feel like I better get a move on. Jesus Christ.

Dr. Natalie Crawford 42:36 It's not information to scare people, but it is information that nobody talks about.

Steven Bartlett 42:41 Well, as you were sat here, talking to me about this, the opposite of confronting the truth is regret.

Dr. Natalie Crawford 42:49 Yes.

Steven Bartlett 42:50 And I can't imagine how much regret you've seen. I wanted to ask you about, about that regret, because you must have to deliver so much bad news to people, and you must see the retrospective clarity that those people suddenly get when they realize that there was decisions they could've made earlier.

Dr. Natalie Crawford 43:12 Especially for people who are not used to not being in control of things and who just didn't have the data they needed to make the decision. There are people who have been with their partner for a very long time, and maybe kids weren't in the plan earlier, but they could've been had they known that it would've been so hard, or potentially impossible later on. One thing that I think's important to discuss here when it comes to regret is testing female fertility, because there is a marker of how many eggs do you have. We call this your ovarian reserve, how many eggs are left in the vault. And one way you can test this is with a blood test called AMH, or anti-Mullerian hormone, and the other way is to do an ultrasound and see how many eggs are outside the vault at that month. So both of these are actually quite important when you're thinking about how many eggs somebody has. That number does not impact you getting pregnant in one month, and I think that that's important, because if you have, well, here's a whole group, you could have a whole group of eggs or you could have less. How many eggs is your body ovulating in each group? So this person, ah, that was crazy. This person who has more is ovulating one.

Steven Bartlett 44:35 Uh-huh.

Dr. Natalie Crawford 44:35 This person who has less is ovulating one. So if I have two people who are the same age and they have different ovarian reserves, meaning they have a different number of eggs left in their vault, they're going to send out a different number of eggs each month. How many eggs are they ovulating each month?

Steven Bartlett 44:54 One.

Dr. Natalie Crawford 44:55 One. Yes.

Steven Bartlett 44:56 Look at me learning.

Dr. Natalie Crawford 44:57 Look at you. So they're each going to ovulate one egg, so what are their chances of getting pregnant?

Steven Bartlett 45:03 The same.

Dr. Natalie Crawford 45:03 The same. So having a lower egg count does not impact your monthly chance of getting pregnant. That's determined by age, by the proportion of these eggs that are normal or abnormal. However, if you have fewer eggs, there's fewer that I can get to grow with IVF, and you have overall less of an opportunity to grow your family. This is important because a lot of societies will tell people not to check somebody's ovarian reserve, and this blows my mind. I have a really hard time with this, because they say if it doesn't impact your monthly chance of pregnancy, having a low ovarian reserve is only going to cause undue stress. So the American College of OBGYN recommends not checking an AMH level in women who are not trying to get pregnant and who are not having infertility. I completely disagree with this, because you can't make decisions on data you don't know, and if you know you're running out of eggs faster, you very well might make different decisions. You might freeze your eggs. You might try to get pregnant sooner. You might try to just be healthier if you are doing behaviors that you know are decreasing your egg count. You might s- stop smoking pot. But if you're never given that opportunity, you're going to live in the regret category, where when you find that out later, "I wish I'd known this earlier. I wish I'd been able to make a choice when I had the opportunity and I had the eggs remaining." And so by not testing, by not knowing, we are hurting more women. And I always tell my OBGYN friends, "This conversation should be hand-in-hand with, 'Steven, are y'all trying to get pregnant, yes or no?' 'No.' 'What birth control might you want? Let's talk about it.' 'Oh, should we check your ovarian reserve to make sure that your time is okay?'" Again, having a good egg count doesn't mean you're going to get pregnant. Your chance is the same. However, it means you have more opportunity of time to try to grow that family, and ultimately, a greater chance of success when it comes to IVF or egg freezing, because the factors that determine success are how many eggs you have and how many are normal.

Steven Bartlett 47:16 A lot of people do ask that question. They ask, um, you know, they'll say things like, "Well, my parents didn't have to worry about this," or, "My grandparents didn't have to worry about getting checked and seeing how m- big my ovarian reserve is, so, you know, why do we have to all start doing that now?"

Dr. Natalie Crawford 47:31 We know a lot more now, and I think the honest answer here is that one way to look at this is that when I was your age, egg freezing didn't exist, so I could not have frozen my eggs in my early 30s had I wanted to. Meaning, would you check it if you really can't offer somebody things to intervene or a way to make a change? However, now, we know factors that impact how many eggs you have and we have the ability to freeze eggs with very high success rates now. It's accessible in almost all fertility clinics with really great egg survival.So this poses the question of should you know earlier? We also have generations where people are curious and they see things online, they're not afraid of scary health information, instead, younger generations want to understand their bodies, and I love that. But there's so much misinformation online too that it's really saying that this is personal. We can talk about eggs in a vault every single day, but until somebody comes into my office or somebody else's office to get their own evaluation done, they're not gonna have the true data they need to make that decision. But I think it's great that we are approaching fertility as a health marker, trying to look for signs earlier that things might be wrong, especially given the opportunity to try to intervene. If you find out your sperm count's lower, we might be able to try interventions for three to six months and see if we can get a new group of sperm that potentially has fixed that problem.

Steven Bartlett 49:06 So say I'm starting out in life with a full ovarian reserve, or say, you know, here's my ovarian r- reserve at say 20 years old. If I start engaging in unhealthy lifestyle choices, if I start eating processed food, if I become obese, et cetera, does that take marbles out of this jar? Does that take eggs out of my reserve or does that just damage the quality of the eggs in the jar?

Dr. Natalie Crawford 49:33 Both.

Steven Bartlett 49:34 Both. Okay. So it pulls them out and it makes them less effective.

Dr. Natalie Crawford 49:38 The way I think about it is not that it's pulling them out, giving them an opportunity, but essentially, let's imagine it's getting... You smoke cigarettes, the cigarette smoke is getting inside the vault, it is damaging the DNA in some of your eggs, but it's also just killing some of them inside the vault themselves.

Steven Bartlett 49:53 Okay. All right.

Dr. Natalie Crawford 49:53 So that you are running out inside the vault. Ultimately, people who smoke cigarettes go into menopause years earlier than the average age.

Steven Bartlett 50:03 Really?

Dr. Natalie Crawford 50:03 Mm-hmm. Because they have had a destruction of the eggs inside their vault.

Steven Bartlett 50:08 If I wanted to make sure that my ovarian reserve was 10 out of 10, you know, I d- if I was to live a perfect life in terms of what my ovarian n- reserve needs to be healthy, how would I live? What would, what would my daily habits look like?

Dr. Natalie Crawford 50:21 That's a great question. I love it. So what can you try to do? Because you can't control everything, but you should be able to control the factors you can. So number one, we're gonna say avoid toxic behaviors. So toxic behaviors, that's going to be your cigarettes, your marijuana, cocaine. You're going to ha- not have any alcohol. Definitely alcohol, especially in proportion, is showing an increased risk of damage. So a drink here or there, like, that's not studied as well, but we know moderate to high drinking levels is associated with reduced egg quality.

Steven Bartlett 50:55 What's moderate to high?

Dr. Natalie Crawford 50:56 Usually considered four drinks a week.

Steven Bartlett 50:59 Four drinks a week? So if I have four glasses of champagne a week?

Dr. Natalie Crawford 51:01 Yep. So you have four glasses tonight at dinner, you've hit moderate.

Steven Bartlett 51:06 That is... I mean, most people, especially in Britain, probably-

Dr. Natalie Crawford 51:10 Oh, well, here too. And I mean, honestly, with COVID especially, we saw so many people increase their drinking substantially. So you would limit the toxic behaviors. Number two is you are going to limit the toxins in your world that you can. Again, if you live in an area that is a high pollution area, that just might be where you live, but you should not cook in plastic, put plastic in the microwave or the dishwasher, you shouldn't use Teflon on your pans, you shouldn't touch thermal paper receipts. Like at the airport, if they print off a ticket for you or a receipt from the grocery store, that has chemicals in it itself. Takeout food. So when you order your takeout food and it comes to you and it sits in the containers that it comes in, if you're not eating it right away, or even when you do eat it, you should take it out of that container and put it in something else. Put it in glass, put it on a plate, because especially with heat, we see leaching of those toxic chemicals into the food, and then you're consuming the food. Even if it's high quality, good food, it now has absorbed chemicals from the packaging that it was in.

Steven Bartlett 52:19 So microwave meals that, in plastic, you know, you take the plastic and you microwave it.

Dr. Natalie Crawford 52:24 Shouldn't do it.

Steven Bartlett 52:26 How do we know this? Uh, have they, have they done research on this or is this just...

Dr. Natalie Crawford 52:30 So there is research done on it. It's always hard to study lifestyle factors in humans and when it comes to fertility, because what is the outcome? Is it the positive pregnancy test, the having the baby, the absence of getting pregnant, the irregular cycles? There's so many different variables you can look at at an endpoint. A lot of the environmental chemical studies are done on animal studies looking at some of these chemicals, but also we can see in population-based studies, we do have now where they've done cohort studies. I mean, they take a group of people and they follow them for years, taking blood and urine samples to measure some of these chemicals and then watching what's happening with their normal behavior. No intervention. Are they getting pregnant when they're trying to or are they not? And we see that greater exposure to these known toxic chemicals are making it harder for people to get pregnant. When it comes to other factors to try to have your healthiest vault possible, decreasing inflammation is going to be very important. So we think about inflammation, and there's two types. So you have acute inflammation, you cut your arm, and it's going to react and heal, and that's a normal bodily process. But then you have chronic inflammation where your body is constantly spending its energy fighting that inflammatory state and that inflammation markers, the prostaglandins, the factors in your body that get really high, that's actually pretty toxic to our quality as well, and that can be disease states as well. So things like endometriosis or other inflammatory or autoimmune diseases.

Steven Bartlett 54:07 What, um, what ways do we voluntarily...... increase our inflammation, is that dietary predominantly?

Dr. Natalie Crawford 54:13 Yes. So number one is gonna be not sleeping enough. So sleep is when your body heals. Sleep is when your cells repair their damage, so you need to get seven and a half to eight hours of sleep per night.

Steven Bartlett 54:25 I heard you say in a quote, "Sleep is probably the number one thing that people d- don't do that does impact their reproductive hormone system."

Dr. Natalie Crawford 54:35 Yes. It seems so straightforward to say it's not a pill that you take, it is not a major change of behavior, it's not missing out on something in your life. It is simply giving your body the time that it needs to heal from the normal inflammation that you're going to encounter during the day. Simply prioritizing getting enough sleep is the simplest thing somebody can do to try to improve their reproduction and how their hormones are made and interpreted.

Steven Bartlett 55:04 We talked about stress earlier.

Dr. Natalie Crawford 55:06 Stress impacts

Dr. Natalie Crawford 55:07 the brain in a similar way. There's different types of stressors very similarly. You have your acute stressor, the bear. You have the stress of everyday life, and s- modern world is a lot more stressful in a lot of different ways constantly. We also see that that stress is so individualized, so it's not like I can say, "You need to go to yoga," or, "You need to do acupuncture," or, "You need to go to therapy." I tell my patients for stress reduction, understanding that having a constantly stressed state, constantly may h- having cortisol be made, is not going to allow your brain to en- to interpret the other signals that are being sent. It's clouding its judgment, and it's going to think that you're not at a place to maybe support a pregnancy and your reproductive hormones are going to show for that. What that comes down to is that you've gotta modify stress in some way for you. So everybody's different, and maybe it is acupuncture, maybe it is yoga. I- I like to sit on the back porch in the morning hours with a cup of coffee and hear the birds. People like to go on walks, therapy, mindfulness, meditation, journaling. Everybody's different, but you deserve taking 20 minutes every day and dedicating it to something that doesn't have your iPad, your cellphone, your computer, the TV, and putting yourself in an environment where you can say, (exhales) like, have that feeling of release you get when your cortisol drops. That's important so that your body can then properly respond when you do have a stressful situation and can allow you to heal, not be under a constant attack. Diet's gonna be one of the hugest things that people can make a change in. Processed foods, refined sugar, processed meats, those are not natural foods and those are things that come with a lot of chemicals inside of them, a lot of contaminants. We know that processed meats, for example, type one carcinogens, all these sugars have a h- direct correlation with somebody's ability to get pregnant. When it comes to the direct cause, it's usually gonna be sperm quality or egg quality, depending on the study

Dr. Natalie Crawford 57:14 looked at.

Steven Bartlett 57:14 What about red meats?

Dr. Natalie Crawford 57:15 Oh, I love that question. Number one, I think it's really important that nutritional studies, people qualify meat differently. So it might be all meat, it might be types of meat. So we have to take it with a g- in perspective of the limitation of the data. We know that processed meats impact fertility. We know that red meats appear to impact both sperm production and egg and embryo quality. There was an IVF study done and the more servings of red meat you had in a week, the less embryos you had develop throughout the process than somebody who had fewer servings. So that's telling us that it's maybe not one red meat in general is bad, one serving, but it's about the amount, right? Everything in moderation. Nothing in excess. We know that the healthiest fertility diet, high in fruits and vegetables. Fruits and vegetables are fiber sources. They are antioxidants. They are helping our body function appropriately. They're helping our gut function. They are lowering inflammation. I say meat is okay. I don't eat meat, but that doesn't mean that none of my patients should eat meat. I give them this diet because I think you have to make dietary change accessible. If I told everybody, "Stop eating meat," nobody's going to listen to anything. But we know that it's the amount, the quantity. So I say if you're going to eat, uh, an omnivore diet, which is gonna be the majority of people, have a meatless Monday. Meatless Monday, you automatically can do and you're gonna have to substitute in some of those other sources of protein that are ultimately better for you.

Steven Bartlett 58:55 Fish?

Dr. Natalie Crawford 58:56 Fish is great. We should limit fish to three times per week just due to risk of mercury, but fish is a wonderful option. It does have a lot of good omega-3 fatty acids in it and ultimately, eating more fish and less red meat is such a great substitute.

Steven Bartlett 59:11 What about skimmed milk and fertility? I heard, uh, I've heard you speak a little bit about that in the past.

Dr. Natalie Crawford 59:15 You have, yes. So what's interesting and I think that we've grown up in this, you know, fat-obsessed culture that has prioritized low fat, no fat foods, and number one, fat is important in the production of steroid hormones. Estrogen, progesterone, testosterone are steroid hormones, so they need cholesterol. The source of that cholesterol is important, so we should have those healthy fats, the nuts, the avocados, the oils. Fantastic. Healthy fats are wonderful. But when it comes to dairy, we've seen that whole fat dairy is associated with better fertility, better ovulation than the skim dairy products, probably due to the processing. If we view skim milk as the processed version, if I'm gonna take out the fat that normally comes in the milk, but still want it to retain looking like milk, it's not just minus fat, right? It's minus fat plus something else. So in the production process, it's that or it's potentially that the only benefit the dairy really has is being a source...... of a healthy fat option, and that when you take out that fat, you lose that. So I recommend that if you consume dairy, that you stick with the whole fat versions, you don't do skim or low fat, and in moderation for, for dairy consumption. I say that if you do meatless Monday, the rest of your meals for the week, you should have one serving of meat per day. That's going to make you, just force you to eat more fruits and vegetables. And then one of those meals, you should have red meat if you like red meat, not multiple times a week. And then you should limit processed foods, sugars, processed meats, all those refined carbohydrates, all the packaged things that are totally fake. That should be very rare. Those are your occ- occasion type of foods, not your everyday

Dr. Natalie Crawford 1:01:05 foods.

Steven Bartlett 1:01:05 Um, a- the other thing we didn't talk about regarding lifestyle choices is exercise.

Dr. Natalie Crawford 1:01:09 Oh, yes.

Steven Bartlett 1:01:09 Now there's kind of two schools of thought here because I have some friends who exercise a lot and they have seen a dysregulated menstrual cycle-

Dr. Natalie Crawford 1:01:22 Yes.

Steven Bartlett 1:01:22 ... or their periods have completely stopped. Um, but I also read that exercise is good for fertility.

Dr. Natalie Crawford 1:01:30 This is a great opportunity to just think about how the ovaries work. We've talked about having your eggs, but if we think about in a given month, you have that group of eggs that comes out of the vault, each egg's in the follicle. We already said FSH or follicle stimulating hormone is the hormone from the brain that goes and stimulates that one egg to grow. As that egg grows, the follicle's growing and making estrogen. That process takes approximately two weeks in the majority of women, and when your estrogen level gets high enough, it tells the brain you have a mature egg. Your brain doesn't know what's happening in your ovary. It can't see. I always say it's like having your best friend who doesn't go on Instagram. They have no idea what's happening in your life lest you tell them. So the only way that the ovary communicates with the brain is actually through the production of hormones. So as that one follicle's starting to grow, it is making estrogen, and that estrogen is then telling our brain, "We have a follicle growing." That follicle then is going to open up. It bursts, it ruptures and-

Steven Bartlett 1:02:27 What's a follicle? Sorry.

Dr. Natalie Crawford 1:02:28 Ooh, a follicle is if we can imagine this is a follicle.

Steven Bartlett 1:02:33 So that's an egg?

Dr. Natalie Crawford 1:02:33 The egg is microscopic inside of it.

Steven Bartlett 1:02:36 Okay.

Dr. Natalie Crawford 1:02:36 It is the fluid-filled structure that keeps your egg.

Steven Bartlett 1:02:38 So for people that are, are just listening and not, can't see-

Dr. Natalie Crawford 1:02:41 Yes.

Steven Bartlett 1:02:42 ... you're holding one of th- little eggs in your hand.

Dr. Natalie Crawford 1:02:43 A m- a marble. I'm holding a marble. So if we can imagine a follicle is a small fluid-filled structure in which the egg is kept.

Steven Bartlett 1:02:50 Okay. So the egg's inside the follicle?

Dr. Natalie Crawford 1:02:51 Exactly.

Steven Bartlett 1:02:52 Got you.

Dr. Natalie Crawford 1:02:52 And so the follicle gets bigger. As the egg gets more mature, it makes more estrogen. That estrogen at a high enough level, and it's very specific, 200 picograms for 50 hours tells the brain you have a mature egg. The brain will then send out LH or luteinizing hormone. It allows that follicle to open up, then the egg is going to be released and hopefully get captured by the fallopian tube. So it'll be sucked up into the fallopian tube. But that follicle re-forms. So the egg is gone, uh, the follicle re-forms and it becomes a cyst in your ovary called the corpus luteum, and it is now stimulated by LH from the brain telling it to make progesterone.

Steven Bartlett 1:03:32 Okay. And what am I gonna do with the progesterone?

Dr. Natalie Crawford 1:03:33 Progesterone opens and closes the implantation window. Without progesterone, a pregnancy cannot implant into the uterus. So this progesterone is going to allow your body to have that egg if it becomes fertilized and develops into an embryo. The egg gets fertilized in your fallopian tube. It has to grow and develop into a stage of an embryo.

Steven Bartlett 1:03:55 So the sperm comes along.

Dr. Natalie Crawford 1:03:56 Sperm swim through the uterus into the tubes.

Steven Bartlett 1:03:59 Okay.

Dr. Natalie Crawford 1:03:59 And that's where fertilization happens.

Steven Bartlett 1:04:00 Ah, okay. So the sperm comes through the fallopian tube.

Dr. Natalie Crawford 1:04:02 Yes.

Steven Bartlett 1:04:02 It meets the egg, which is chilling there.

Dr. Natalie Crawford 1:04:04 Chilling there.

Steven Bartlett 1:04:05 And then what happens?

Dr. Natalie Crawford 1:04:06 Then... Well, hopefully fertilization happens.

Steven Bartlett 1:04:09 Which is like the sperm, which is like the tadpole's head hits the egg and then...

Dr. Natalie Crawford 1:04:11 Hits the egg.

Steven Bartlett 1:04:12 It actually has a little fusion reaction and pushes its DNA in there. Hmm.

Dr. Natalie Crawford 1:04:17 Pretty cool. It then has to grow and develop. So you have a single cell egg, a single cell sperm, they come together, you have two different DNA components.

Steven Bartlett 1:04:25 Okay.

Dr. Natalie Crawford 1:04:25 And then you start seeing cell division just like you would expect exponentially. Two cells, four cells, eight cells, 16 cells into the point where on day five or six that embryo is now a what we call a blastocyst. It's 300-ish cells and it is now at the stage where it can implant into the uterus. What is so interesting is that most your eggs are never going to fertilize, they're not gonna grow appropriately, they're not gonna get into that uterus. But what's so important is that if an egg is coming in or the embryo's coming in and there's not just the right amount of progesterone, it cannot implant. That's really important because that's the mechanism behind a lot of birth control, but when you think about progesterone starts being made from this corpus luteum perfectly timed after you ovulate to open and close that implantation window so that when the embryo gets there, it's ready. And if the embryo doesn't implant, hangs out too long, it's going to close. The corpus luteum only lasts for two weeks if it is not supported by a pregnancy, meaning if we pretend this month you don't get pregnant, you're just having natural periods, then the corpus luteum, after two weeks, it dies. Your progesterone levels are going to drop and that's the signal to your uterus to shed the lining in preparation for the new group of eggs. That's your body saying, "We did not get pregnant this month. Let's try again." When a pregnancy implants, that embryo makes a hormone called HCG, which is what we check on a pregnancy test, and HCG can stimulate the corpus luteum to keep making progesterone and that is what allows you to sustain an early pregnancy until there's a placenta. The point of thinking about that, which there's a lot to go into about optimizing intercourse and trying to get pregnant, is that things that disrupt the brain's interpretation of estrogen...... is going to impact your ability to sense ovulation or to ovulate, and going to lead to menstrual irregularities or absent periods, like you mentioned in some of your friends who exercise maybe more frequently. So on one end of the spectrum, if you are intensely exercising, you're training for the Olympics, you're an elite athlete, your body is going to stop sending out FSH and LH altogether. It is going to say that the calories you're receiving to the energy you're expending do not match up, and you cannot support being pregnant with another human. So it is going to stop the production of FSH and LH, and you're not going to ovulate. You're probably fine 'cause you're training for the Olympics and you don't wanna be pregnant right now. This also happens, though, with eating disorders, anorexia, for example. We can see that... I will say when the brain is turned off, when your brain has decided that you can't be pregnant right now, it takes years of being in recovery for it to turn back on. It has to be convinced for years that the system is going to be intact again. And the part of the brain that controls if FSH and LH are released from the pituitary is called the hypothalamus. So we call this hypothalamic dysfunction. I like to think about the hypothalamus as the, you know, airport control station; they're watching the planes come in and sending out other signals. It is interpreting what your body's giving it, and then it's directing what is happening. Estrogen is also made from fat cells, and this is one of the reasons why being overweight is so impactful when it comes to your reproduction. Because if your body is making extra estrogen, your brain thinks an egg is on the process of growing. So it's... Because, right? The brain thinks estrogen's only made from an egg. So if it sees some extra estrogen because you're obese, it's not gonna send out a strong enough signal to get an egg to grow, because the brain wants to send out just enough to get the one egg to grow; it doesn't want 20 eggs to grow. So if it sees that estrogen, it's gonna say, "Ooh, an egg's already growing, I'm gonna send out less." But there is no egg because you're overweight; it's the fat cells making estrogen. And so exercise comes into this play where exercising, if you're overweight, can be extremely beneficial for your fertility, because if you lose weight, you drop that baseline estrogen level down, and now your brain can more clearly interpret the signal from the ovary. So suddenly, your system is back in check; same thing for men. Estrogen, when men are overweight, goes to the brain, and the brain... Estrogen and testosterone are on the same conversion pathway. So the brain says, "Oh, Steven's gained some weight. I- I see his estrogen. He's making enough sperm, we're good." And it's not going to tell you to make as much testosterone or as much sperm as you need. And then you get on this pathway where you have less energy because your testosterone is low, but you're gaining weight, and you can't get that testosterone higher. You go to the men's health clinic, and they're gonna draw your blood, and your testosterone will be low, and they're gonna put you on that TRT, and now your sperm count's gonna go to zero. So sometimes that entry point to the whole problem was having extra fat tissue. So exercising to lose weight can be very beneficial for your fertility for men and women. There's a lot of talk on hit exercise or moderate activity, and for the regular person, whatever you will stick with is the best. If you're trying to get pregnant, you should not be trying to stress your body to new goals, training for the marathon, doing something-

Steven Bartlett 1:10:05 If you think going t- going to the gym every single day, is that too much?

Dr. Natalie Crawford 1:10:08 No. I usually say going to the gym every single day, if we think about 60 minutes or less, is a normal amount of inflammation from your muscles. That is good. Your body should encounter some challenge along the day. Having more muscle is also going to help combat insulin resistance and other issues that come in and interfere with our brain's interpretation of our hormones as well.

Steven Bartlett 1:10:30 Mm-hmm.

Dr. Natalie Crawford 1:10:30 So we see that both over-exercising and not exercising are the extremes that are not gonna be helpful for you. But moving your body, in addition to helping your hormones function better, less chance of becoming overweight, better interpretation by your brain of your body's signals, it's also a great way for stress coping and lowering your cortisol levels. So exercise, we should put there, right up there with the top thing somebody can do; get more sleep, exercise every day.

Steven Bartlett 1:10:58 You mentioned menstrual cycles there and how they can be disrupted for long periods of time. Um, my partner shared quite openly, um, on her social media channels her battle with this, and she, I think she had a couple of dietary changes, she had some struggles with eating, and that resulted in her period basically stopping for I think three or four years. Um, it's returned after sort of three, three or four years, and she's v- very happy about that, but, um, lots of people are going through irregular period cycles, irregular menstrual cycles. What can you say to this? I mean, what is, what is, quote-unquote, "normal" as it relates to a normal healthy- healthy menstrual cycle, and to people that are struggling, what- what would you advise them, and what would you tell them?

Dr. Natalie Crawford 1:11:39 I love it. A normal period is one that is regular and predictable. So I'll tell a patient, "You can look at a calendar, and you can say within a couple of days of certainty when you're going to have your period." Now, each individual person is going to have a different cycle length, meaning the day from the start of your bleed, that's day one of your cycle, until the last day before your next period bleed. You'll hear 28 days used a lot; that's not the average for every single person. Usually, it's gonna be between 24 to 35 days for the average person.

Steven Bartlett 1:12:13 Can you explain this to me-

Dr. Natalie Crawford 1:12:14 Yes, yes.

Steven Bartlett 1:12:14 ... like, I've never heard of a menstrual cycle before? What is it? What happens?

Dr. Natalie Crawford 1:12:18 So the menstrual cycle is-... is essentially what we've talked about with our whole eggs, right? So you have your group of eggs come out of the ovary. Each egg's in a follicle. Brain sends out follicle-stimulating hormone. That egg's gonna grow, develop, and ovulate. That's gonna put you a couple weeks into your menstrual cycle. From there, it's going to then make progesterone, get you into that back half of it, that luteal phase, 'cause the corpus luteum is always set at two weeks. And then when you're not pregnant, you're going to bleed. So bleeding is the shedding of the lining. That's your period. Your ovaries are doing something different throughout that process. So while you're bleeding and on your period, your ovary is already starting to grow the egg that's going to ovulate in that month, and as that egg makes estrogen, that's what stops you from bleeding.

Steven Bartlett 1:13:05 Okay.

Dr. Natalie Crawford 1:13:05 So when you have your period, that's the shedding of the lining from the last month because you didn't get pregnant, and growing an egg this month, once there's enough estrogen, is going to stop that process and stabilize that lining.

Steven Bartlett 1:13:19 Okay, so typically when you... if y- if there's no other interventions, if you don't have your period, it's because you're pregnant.

Dr. Natalie Crawford 1:13:24 Because you're pregnant or you didn't ovulate, because you have to have that progesterone drop as the signal for your body to bleed.

Steven Bartlett 1:13:30 To shed. Sure.

Dr. Natalie Crawford 1:13:31 Exactly. So you either... Problem A, "I didn't ovulate." So that is either, "I'm out of eggs, I don't have any eggs to ovulate," or, "My brain didn't send out the signals," like we said, hypothalamic amenorrhea. That's often that over-exercising or that calorie restriction or chronic illness.

Steven Bartlett 1:13:49 Stress?

Dr. Natalie Crawford 1:13:49 Stress, sometimes. I, I like to think about that one often more as hypothalamic dysfunction, like probably irregularity versus absent, but yes, stress. And then we've got pituitary end, thyroid disease, prolactin. These are hormones from the pituitary gland, which is where FSH and LH come from, and if your pituitary sends a lot of energy to making thyroid-stimulating hormone, it's not gonna send out FSH quite as well. And then you have polycystic ovarian syndrome, which is going to be one of the most common causes of female infertility and of irregular periods, and that is when your ovary and your brain have a miscommunication. And so when we talk about irregular cycles, 'cause we should dive into PCOS, what we're saying is that for one single person, it's not occurring at this regular interval for them. So maybe it's 25 days for Jill and 30 days for Mary and 34 days for Suzy, but each of those people should be able to know when her period is coming. The fertile window for all of them is the s- is different, and that's why apps and cycle tracking can be really problematic, because what the fertile window is, is going to be the five days before and then the day you ovulate. So an egg lives for 24 hours.

Steven Bartlett 1:15:05 The five days before you ovulate. Okay. Okay.

Dr. Natalie Crawford 1:15:07 So the five days before you ovulate and then the day that you ovulate. The egg lives for 24 hours. It has to be fertilized while it is in the fallopian tube, in those first 24 hours. Sperm can live in the female reproductive tract for five days. So that is why we will tell people to have sex before and then during ovulation. Put some of that sperm from the locker there a little bit earlier and then get some there right, right at the time when you're ovulating to see if you can fertilize that egg. If we think about understanding when your fertile window is based on your cycle length, so if we say your cycle is the, the entire process and then your period is just the bleeding days, the entire process, if your cycles are on average 28 days, the corpus luteum lives 14 days. So 28 minus 14, you, on average, would ovulate on day 14. So the five days before and then day 14 are gonna be your most fertile days to try to target intercourse or avoid, if you don't wanna be pregnant, and if your cycles are 35 days, though, it's very different, right? Because now 35 days minus 14 is going to be...

Steven Bartlett 1:16:17 21?

Dr. Natalie Crawford 1:16:17 There you go, 21. So your fertile window, or for that person, is gonna be cycle day 21, so now the five days before and day 21. So those are very different fertile windows, days they should be having sex.

Steven Bartlett 1:16:30 It's a lot, isn't it? Do we just have sex every day, if we can?

Dr. Natalie Crawford 1:16:33 So absolutely, like if you can have sex every day or every other day and you don't have to track your cycles, if they are coming regularly and you're putting sperm in the presence of the egg by every day or every other day sex, absolutely. And that's one of the things that I see people do wrong the most is have less sex in the idea that they should save it up to put more sperm present when the egg is arriving.

Steven Bartlett 1:16:57 I have to say, I mean, there's a few things I wanted to say about this. So I think... What's the first thing I wanted to say? The first thing I wanted to s- to ask is how long, on average, do different age groups need to try before they hit the bullseye?

Dr. Natalie Crawford 1:17:13 If you're age 30 and you're trying to get pregnant, you have a 20% chance of pregnancy per month.

Steven Bartlett 1:17:18 Okay.

Dr. Natalie Crawford 1:17:19 This means that the majority of people should be pregnant within six months. Infertility is defined as trying for a year and not getting pregnant within that year, so kind of going off the curve of that standard deviation. Importantly, trying to get pregnant means that you're having intercourse, you're ejaculating inside, and you're having regular periods. If you're not able to complete the act of intercourse and you're not having regular periods, people should not wait X amount of time to come see a doctor. You should go be seen right

Dr. Natalie Crawford 1:17:50 away.

Steven Bartlett 1:17:50 When my friends tell me that they've started trying, I always think, "God, that doesn't... Doesn't that just ruin the fun?" You know what I mean? 'Cause I have this one friend who was telling me that, um, because they're trying now, sex has become such a-

Dr. Natalie Crawford 1:18:03 Like chore.

Steven Bartlett 1:18:03 ... like a chore, and if he's away when she's most fertile, then she gets annoyed at him. And I just think, "God, it's so crazy what's happening with sex in that regard, that it's we're now, because we're having kids later and later and we're leaving things a little bit later than ever before, we're now having to..."... treat making kids almost like a, as you say, like a chore. It's becoming, like- I don't know, there's something about that that I'm like, "Oh, gosh," like-

Dr. Natalie Crawford 1:18:29 Well, it's a good point-

Steven Bartlett 1:18:30 ... it could become a job.

Dr. Natalie Crawford 1:18:30 ... because if you're waiting later and you still wanna have more than one child, there's a lot of pressure on it. If you're starting at 35 and you have that 10 to 15% chance per month, if you're starting at 38 and now it's five to eight percent per month, if you're 40 it's three to five percent.

Steven Bartlett 1:18:46 Isn't pressure like the opposite of sex?

Dr. Natalie Crawford 1:18:48 Right?

Steven Bartlett 1:18:48 Do you know what I mean?

Dr. Natalie Crawford 1:18:48 It doesn't sound very fun. I think that, one, having realistic goals is helpful because if you're trying to start your family at 37 and you want four kids, it is very unlikely to happen without intervention like IVF saving embryos for the future, which we can absolutely do, and we do that for people sometimes so that they can go have fun with their sex life again. Two, you feel like you have to track your cycles and time intercourse appropriately when you're older because there's so much that you can't do, right? You only have so many eggs, you only have so much time, and you're trying to do what you can. Understanding your cycle tracking for a woman is a reflection of her full health, how's your brain interpreting your entire body, so it is helpful because if you have irregularity, it is a sign that things are not working normally. That being said, regular sex is good for so many reasons and in a relationship that if you can establish sex more frequently as just part of your relationship, it becomes less burdensome that you're here recording a podcast at this time or somebody's out of town this one given month. If we remember that sex, or the- if we remember that sperm live in the female reproductive tract for up to five days, most of the sperm is gonna live there for two to three days. So five is kind of, like, the longest it can. What we have is that, okay, have sex two or three times a week.

Steven Bartlett 1:20:11 What a- what about couples that can't? Because I- I've sat here and interviewed so many sex therapists and sexologists, if that's even a thing, and we often speak about sexlessness, people having sex less and less than ever before because they're so busy and they're so stressed in their lives, and you must meet so many couples in your practice that, you know, you- you look at them and go, "Well, really, the problem here is you're just not having sex with each other."

Dr. Natalie Crawford 1:20:31 100%. And sometimes it's situational. Truck drivers, pilots, they're just a job where it is too hard to have that intercourse during the fertile window, but then also, yeah, high-performing people, or who just don't prioritize or don't enjoy that part of the relationship. We certainly do what we call IUI or intrauterine insemination, and this is where you take the sperm and you're putting it inside the uterus. So instead of intercourse, we are taking an ejaculated sample, and then processing it and putting it in the uterus.

Steven Bartlett 1:21:02 Wait, so...

Dr. Natalie Crawford 1:21:02 Yes.

Steven Bartlett 1:21:03 I could just ejaculate in a Petri dish, get- get a little pipette, and psst?

Dr. Natalie Crawford 1:21:10 I mean, you can't do it yourself, but-

Steven Bartlett 1:21:13 W- why?

Dr. Natalie Crawford 1:21:13 Well, because most of the ejaculate of your sperm is actually meant to protect the sperm from the acidity of the vagina, so most of that is not ever going to see the inside of a uterus. And if we put the whole sample up in the uterus, it would cause a huge inflammatory or infectious process. But if we clean that sample and we pellet out, centrifuge it, and get just the sperm, we can then put the sperm into the uterus and avoid having all that protective ejaculate sample with it.

Steven Bartlett 1:21:43 You must hear couples doing this kind of thing.

Dr. Natalie Crawford 1:21:46 People do the craziest things.

Steven Bartlett 1:21:47 Tell me about some of the crazy things.

Dr. Natalie Crawford 1:21:48 People do crazy things. I mean, definitely people are having intercourse and then they're putting, they're putting tampons in afterwards to try to keep the sperm in place, or diaphragm cups. People are trying to get their own versions of pipettes or turkey basters, right? That's what people call it, and try to pull up sperm, and put, just put it in their vagina. The craziest stories of sperm procurement come from people who are using donor sperm. As you may not know, there is an entire, like, dark web of sperm donation being connected on Facebook groups and other places where people are not going down traditional roads of using a sperm bank. A sperm bank, pros and cons, but if you're using sperm- i- if you're using donor sperm, a sperm bank is going through a process to make sure there's no infectious material in there, that the information is tested, that there's limitations, but ultimately, like legally too, that that is your sample. These Facebook groups, people are just connecting where you can meet in a Walmart parking lot and drop somebody your sperm out of the goodness of your heart so that they can