Count Down: Why Why Sperm Counts and Male Fertility Rates are Dropping with guest Dr. Shanna Swan

Today, I’m delighted to be interviewing Dr. Shanna Swan. Dr. Swan has a PhD and is one of the world’s leading environmental and reproductive epidemiologist and professor of environmental medicine and public health at the ICAHN School of Medicine at Mount Sinai in New York City. She is an award-winning scientist. Her work examines the impact of environmental exposures, including chemicals such as phthalates and BPA on men’s and women’s reproductive health and the neurodevelopment of children. She is the author of Count Down: How Our Modern World is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperiling the Future of the Human Race.

Dr. Aimee: Dr. Shanna Swan, welcome to The Egg Whisperer Show. I just have to throw in #CountMeIn, because it’s so important for us to talk about this and bring attention to something that is so important to the future of our families. It is such an honor to have you here today.

Dr. Shanna Swan: Thanks for inviting me, Aimee. I’m really pleased to be here and to tell you about my book, Count Down.

Dr. Aimee: Can you tell us a little about your background, and how you got interested in studying fertility and environmental issues?

Dr. Shanna Swan: Sure. I got interested in sperm decline in the late-1990s. I was part of a national committee at National Academy of Sciences, and they wanted to know whether a paper that had come out then in 1992 was something they should worry about when they talked about risks of environmental chemicals and hormone disrupting chemicals. This paper actually claimed that there had been a significant decline in sperm count. It didn’t convince me, I have to say. I was a skeptic originally. That’s my nature, that’s what I do.

I had some time, so I said I would try to understand whether this decline that they reported could be due to other things. We’re all familiar with that. Maybe the way sperm was counted changed over time in a way that later counts were lower. That could happen. Maybe the men who came in later, more in recent years, were selected in some way to have lower sperm counts. Maybe they were more obese. Maybe they smoked more. Maybe this or maybe this.

I took six months, actually, to answer this question. I involved two colleagues and together we went through 61 studies that gone into analysis and looked for all of those things. Then we put them in a big model and analyzed the data. The decline did not change at all, not to the first decimal place. I began to think there’s something going on here.

I spent the next 20 years trying to figure this out. The more I studied it, the more convinced I was A) that it was real, B) that it was not going away, and C) that it was related to our environment. That’s a large part of what Count Down is about.

Dr. Aimee: I watched one of your really incredible talks that you gave on YouTube and you just frame it in such a way that is really eye-opening. I think one of the things that you were talking about was to imagine being part of an experiment where you’re being poisoned your entire life, from the time you’re basically in your mother’s uterus, and then you’re like, “but it’s not an experiment.” That’s just holy smokes, when you frame it like that, it’s very compelling.

Let’s jump to the chase. Sperm counts, testosterone, and male fertility rates are dropping. What has the decline truly been over the past 40 or 50 years?

Dr. Shanna Swan: The rates of these declines in fertility — by the way, fertility, as you very well know, a couple phenomenon — I prefer to say couple fertility has declined at 1% per year everywhere. Everywhere, which is so shocking. Testosterone has declined at 1% per year. Sperm count, sperm concentration, and problems have been going up. Miscarriage increasing 1% per year. Ovarian reserve has been decreasing.

So, there is something going on that is tying these things together in men and women, and by the way, in nonhuman species as well. While there are a lot of things we do in our daily life that affect our fertility, as you well know, there are things that we have very little control over, the things that are, if you will, administered to us as subjects in a huge experiment that we’re part of without our consent. We can talk about those in more detail.

Dr. Aimee: Some people have called this phenomena Spermageddon. It seems appropriate and sort of terrifying at the same time. What is exactly happening to the sperm?

Dr. Shanna Swan

Dr. Shanna Swan: Oh, there’s so much happening to sperm that is concerning, I’m sure to you, too, as a physician in this area.

I would say the easy end of this is what happens to an adult male. That’s easy because he can change things that are adversely affecting his sperm, and he should. I’m sure you give this kind of advice. Smoking, binge drinking, stress — good luck with that these days, but stress — obesity, lack of exercise, even heat, are things that can affect a man’s sperm count. But you also know that if he changes behavior, he can improve his sperm count. There are many examples of that, of guys who couldn’t get it together, couldn’t do it, who changed their behavior and then they could. That’s the good news story.

The bad news story is that there are other changes that occur that nobody can do anything about. Those are changes that happened a long time ago in the womb, and those are changes that followed the exposure of the mother when she was pregnant or even the father around the time that he was, if you will, preparing the sperm that was going to make that fertilized egg. Those 60 to 70 days during which sperm is being produced are very sensitive to exposures which will then impact the developing fetus. Those changes, which we can talk about what happens, are not reversible, those are lifetime changes and some of them get passed on to future generations as well.

Dr. Aimee: I have this dream, and I hope one day it will be realized, where somehow three months before you’re planning a pregnancy you get these pre-pregnancy kits with guidance for what to eat, how to live, etcetera. I think it would just be incredible, before people even start trying to conceive you get some sort of pre-pregnancy kit that is delivered to you, and then even throughout the pregnancy with pregnancy-safe containers to eat out of, cosmetics, hints and tips that people just don’t know about. Don’t you think?

Dr. Shanna Swan: I think that’s a great idea. Bearing in mind that their actual conception might be many months later than they thought it would be, so they might have to do this for quite a while, which is a good thing.

Dr. Aimee: Maybe Count Down could also be, you go to a link on your website and then you could also subscribe to some sort of pregnancy kit. One day. We can only dream.

You were mentioning about some of the things that happen downstream. What are those things?

Dr. Shanna Swan: I study a specific class of chemicals. The chemicals that I study are those that have the ability to interfere with our body’s hormones. As you know, your hormone health is extremely critical to this whole process of conception and pregnancy and birth. All along the way, we need the right hormones at the right time to do this complicated job which is taking place unseen from conception to birth. That is the most sensitive period in an individual’s life, those nine months, and particularly the first three months.

Photo by Nick Fewings on Unsplash

When I got involved in this, which happened when a friend was on a plane with me and he said, “Shanna, you should study phthalates,” and I said, “What are phthalates?” as many people do. He told me, and he said that these are chemicals in our daily life and the Center for Disease Control has shown that everybody in the United States has these in their body, including pregnant women. That’s one fact.

The second fact was that around that time toxicologists at the National Toxicology Program had been doing experiments to see what these chemicals did to rodents that were exposed. What they found was so startling that they called it the phthalate syndrome. There’s not too many chemical exposures that have a syndrome named after them. I think alcohol syndrome, fetal alcohol syndrome. Usually, they’re not consistent and predictable. They showed that when the mother rat was exposed to phthalates at a critical time early in pregnancy, which we can talk about, then it infected the boys. Not the girls, but the boys were born with their genitals not quite as they should be, they would not completely masculinized.

That happens because several phthalates have the ability to interfere with testosterone, they actually lower the body’s production of testosterone. Why is that important? It’s important because when the genital tract is differentiating going in the male or female direction, depending on your genetic sex, that process in males requires testosterone, it requires enough testosterone at the right time. If it’s not there, then the male doesn’t complete that journey and then he’s not completely masculinized. No man wants to hear that. Right?

Dr. Aimee: Right.

Dr. Shanna Swan: We can talk about the next steps, but I basically got very interested and I wanted to see whether that was happening in humans. Long story short, after 20 years of doing two very large and very expensive studies where we actually saw how mothers’ phthalates were related to boys’ genital development, I concluded that phthalate syndrome exists in humans.

Dr. Aimee: How small of a change were you really looking at when a female rodent is pregnant?

Dr. Shanna Swan: How much change in the boy?

Dr. Aimee: How much of an exposure caused how much of a change?

Dr. Shanna Swan: The exposure levels that were associated with these changes were low, but they were not extremely low. They were the levels that 25% of the U.S. population is exposed to, so they’re not rare occurrences.

The changes that they caused were also not very dramatic on an individual level. If you look at these boys, you won’t think, “Oh my gosh, the poor kid.” Not at all. We’re talking about millimeters of differences. Just like lowering lead or raising lead changes IQ, that’s a different story, but that’s an example of another low dose that makes a big effect for a whole population. We’re talking about changes on the population level.

We can get to that story in a minute. It turns out that those changes in the genitals actually translate to clinical changes and lifetime fertility and health.

Dr. Aimee: What can people do to make a difference for themselves and their own fertility? I’d love for you to address it both from an individual standpoint and at a societal level.

Dr. Shanna Swan: That’s a very hard question for two reasons. The personal changes, the ones that you’re going to make to minimize your exposure to these phthalates or other chemicals that can change your hormones, those changes are difficult because a lot of our products aren’t labeled. We don’t see cans of spaghetti sauce labeled “contains DEHP.” Not at all. So, we don’t have the option to buy something different that’s unexposed, because there is no labeling.

Photo by Sigmund on Unsplash

There are some examples, but they’re misleading. Bisphenol A is another chemical that changes hormones. It actually makes plastic hard, where phthalates make plastic soft. Many people look for that BPA-free label. Right? But what they don’t know is, yes, it can be free of BPA and it may not be safe if it contains lookalike chemicals such as BPF or BPS that don’t have the same name, so they can honestly say BPA-free, but these alternatives, lookalikes, have the same risk.

What is a consumer to do? They get the advice from you and other people saying to avoid these exposures, they try, they go to the store, they look for these products, and they can’t really make an informed decision.

I think we really have to change the way these chemicals are handled. Actually, I think we have to go a step back and keep them out of commerce all together. We should not be exposed continually to hundreds of chemicals that can alter our hormone systems, which we are.

By the way, it’s not just about fertility. It’s also about brain development. It’s also about thyroid function. It’s also very relevant these days about the immune system. We are weakened, if you will, by the presence of these chemicals in our lives.

What has to happen? The chemicals have to be swapped out for those that don’t have these properties and the government has to regulate them in a way that protects us, which they actually do not.

Dr. Aimee: I know that there’s another publication that stated that this is kind of where global warming was 40 years ago. What do we need to do to turn the tide on this?

Dr. Shanna Swan: The reason I think we are where we were 40 years ago is that if you go back and think about climate change, initially people didn’t believe it, and then they believed it when they saw the evidence, but they said that’s not human doing, that’s just happening. Now people are recognizing that we can make changes in our lives that can help. I think the same process is going on, but we’re late here with the reproductive health.

Initially, in 1992 when that paper came out saying sperm count had declined, it was denied, even by me. Then as people got wiser, they began to realize it actually has declined and that decline is not slowing down. But they said it’s just happening, it’s not about human choice or endocrine disruption. Now they’re starting to accept that these chemicals can play a role and cause this decline.

I think what we have to do is pretty quickly make changes to the chemicals that are in our lives and the regulations of these chemicals in order to slow the decline. It is continuing. When we looked at the last 40 years, then 30 years, then 20 years, you would hope to see it flattening out, but we didn’t see that. Unless we do something to stop our exposure to these chemicals, it’s just going to hit zero.

Dr. Aimee: Can you give us some of your predictions based on your research, as far as when that could be?

Dr. Shanna Swan: That’s a difficult thing. I’m a statistician, I don’t like to extrapolate past my data. I could say hypothetically, yes, you can extend the line. Whether that is reasonable, whether we’ll make changes, I certainly hope it’s not what’s going to happen. If everything continued along that same path, by 2045 that line would hit zero.

That’s median, that’s half less and half more, and sperm count can’t be negative, so half the population would have a sperm count above zero, but it would be low. We would be dependent on artificial or assisted reproduction to conceive.

Dr. Aimee: Right. That’s actually a prediction that I’ve made as well, not as far as the date, but I predict that very soon, probably in the next generation, we’re going to be doing sperm aspirations at the same time as egg retrievals to create embryos, and that’s going to be the new normal. So, you’re going to have a urologist doing his part and the fertility doctor or the IVF specialist doing the egg part for people to continue to procreate.

Dr. Shanna Swan: It’s scary, isn’t it?

Dr. Aimee: It is. I don’t want it to come to that. That’s why, when I read about your book, I was very excited to have you come on here, because I feel like the more people we can reach, the more of a difference we can make. That’s why your message, your book, and your research are so important to our existence.

What do you think fertility doctors need to know about this situation? What would be the most important thing for them to take away from your book and your research?

Dr. Shanna Swan: I think fertility doctors, first of all, should recommend that all men understand their own fertility and not wait until there’s trouble to get a sperm count. We haven’t talked about this, but I’m sure you know that men who have a low sperm count have higher morbidity in many areas and earlier mortality. So, it’s an important sign. The sixth vital sign, if you will, that men should be aware of. Men don’t like this. They just say, “I’m good to go, I have no problems.” Well, how do they know that until it’s put to the test?

I think that the medical community should become more educated on this issue, so they understand what’s going on. It’s not very well known, as you know, and I think that’s a real problem. I think back in medical school there should be courses on this, there should be questions on the exams on the role of environment on fertility and reproductive health.

I think they should have that kit that you talked about where you can advise eat unprocessed foods, try to eat organic if you can afford it, watch the products that you rub on your skin, etcetera. If you read Count Down, we have lots of recommendations on what to do.

Dr. Aimee: I love it. I’m going to be recommending Count Down now to all of my patients, no doubt about it.

Dr. Shanna Swan: Great.

Dr. Aimee: There’s so much of what I call sugar coating of sperm, where people get a sperm analysis and there are abnormalities and they’re told, “Oh, it’s just fine,” rather than saying, “These are the recommendations that I have for you to make it even better.” Fine just isn’t going to be enough, I think, for a lot of people.

If someone wants to find out more about your work and your book, where can they go?

Dr. Shanna Swan: They can go to my website, which is simple They can put in to one of their favorite booksellers ‘Count Down Shanna Swan’ and they’ll see it. If they do that and they have the opportunity to write a review, if they like the book, or even if they don’t, I’d love to hear their opinions about the book.

Then I love people to use #CountMeIn if they want to be part of this growing concern and movement of trying to fix this problem.

Dr. Aimee: Absolutely. Is there anything else you’d like to share with us today?

Dr. Shanna Swan: I want to thank you for your interest in this and for you helping so many patients, reaching out, and educating people. It’s so sorely lacking in the profession and I’m glad you’re here, Aimee.

Dr. Aimee: Thank you, Shanna. I’m certainly glad you’re here, too. Thank you. Awesome. Shanna, I love it. I really appreciate all of this. I love your work.



Fertility Doctor, Reproductive Endocrinologist, Egg Whisperer:

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