Why Is Male Fertility Crashing Globally? - Dr Michael Eisenberg

Global sperm counts have declined by over 50% in the last 40 years. Is that true?

(laughs) You know, it really is. I think, you know, in the last few years, there's been a lot of consensus around that. Uh, you know, one of the most famous studies that looked at this was published in the '90s, um, and, you know, when it was released, I've talked to some of the authors about it, there was a lot of fanfare around it. You know, they had it in a big, um, media hall. There were television cameras. Uh, but since then, there was a lot of controversy around it, um, you know, for a few reasons. You know, there is... You know, there are differences in semen quality around the world, like for example, there's a study in the United States that showed that, if you can believe it, sperm quality is higher in New York than in the Midwest. And I think reasons for that are not certain, you know, whether it's lifestyle, you know, activity levels. There may be differences in, you know, just sort of race/ethnicity composition. I think the reasons are not known, but, you know, in the US we see that, but around the world we see that too, and so there were some concerns about how all that was incorporated into some of these studies. Um, you can imagine over 40 years some of the methodology for testing sperm has probably improved a little bit. And even our, you know, statistical methodologies compu- computational abilities have improved. So, you know, initially in the '90s, I think it was somewhat controversial. Even some of my mentors questioned this. But I would say over the last, you know, few years, there's another study in 2017 and even 2023 most recently, and it's really kind of solidified, and now there's consensus in the field that we're seeing this decline. You know, over the last 50 years, maybe it's called about 1%, so maybe about one million less sperm per year on average every year. But over the last, you know, 10, 20 years, it's accelerated actually about 2%, uh, decline. And so, I think it's... You know, now that there's a little more, um, you know, again sort of consensus around it, I think it's really up to us to understand why, 'cause, um, yeah, it's not- not a good thing. Existential, I think, in a lot of ways.

Okay. Why do we think that this is happening, uh, beyond the ability to detect statistical improvements physically? What- what- what's happening?

Yeah. I mean, I think that's the million-dollar question, or billion or trillion-dollar question really. Um, I think there could be a few reasons. You know, the pace of change is probably too quick for evolution. I don't think it's a genetic factor, you know, so I think people have really honed in on exposures, you know, whether it's, you know, lifestyle factors. I mean, I think that, you know, we're probably a little less sedentary than we used to be. You know, obesity was going up, although maybe with some of the new medications, we'll see a reversal of that trend. But I think there's a lot of concern about just some of our exposures, you know, some of the chemicals in the environment, microplastics, I think those sorts of things. You know, there're some endocrine-disrupting factors that are at play here that- that may be the culprits, but I think, you know, we need to really do more work to try and understand it, um, and I think that's kind of where we are.