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Why is getting pregnant so difficult these days? An interview with Dr. Shanna Swan on her new book

Dr. Shanna Swan

Count Down: How Our Modern World Is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperiling the Future of the Human Race, by Shanna H. Swan, Ph.D., peels back the curtain on a hidden danger all around us: toxic chemicals that are wreaking havoc on our reproductive health.

The new book, in the tradition of Silent Spring, reveals that:

  • Fertility has dropped more than 50% over the past 50 years worldwide
  • In some parts of the world, 20-something women today are less fertile than their grandmothers were at 35
  • A man today has only half the number of sperm his grandfather had

What is contributing to these frightening statistics? One major factor is our exposure to hormone-disrupting chemicals like phthalates, which are found in everything from vinyl plastics to perfume and cleaning products. These are some of the very same chemicals we are campaigning to eliminate at major retailers and through state and federal policy reform.

Dr. Swan is one of the world’s leading environmental and reproductive epidemiologists and a professor of environmental medicine and public health at the Icahn School of Medicine at Mount Sinai in New York City.

We recently spoke with Dr. Swan about her new book. Check out our interview with her below. You can get a copy of her book at your favorite local bookstore or

What inspired you to write your new book, “Count Down: How Our Modern World Is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperiling the Future of the Human Race”?

I have been researching, speaking, and writing about environmental chemicals and reproductive health for decades, but awareness of this issue, outside the (relatively) small circle of environmental scientists, has not grown. The response to our 2017 meta-analysis of sperm decline was different. Finally, after working on this issue for over 20 years, it looked like this question was being taken seriously and this paper became one of the most viewed and cited publications of 2017. So, when a literary agent asked me whether I would be interested in writing a book about this, I agreed, in the hope that this would be a way to reach people I hadn’t been able to speak to through academic channels.

What are the main points you hope readers come away with?

The first step toward making change requires admitting we have a problem, which our society hasn’t done. Here are the problems we have to face up to:

Sperm count, fertility, and testosterone levels are declining while pregnancy loss or miscarriage and premature ovarian failure are increasing all at the same rate: 1% percent per year, which suggests common causes for these problems.

Fertility rates are dropping and increasing numbers of couples are turning to assisted reproduction. But the problems only start there because reproductive health is a sentinel for lifetime health and longevity. This is now so well established that an expert panel suggested we think of reproductive health as “the sixth vital sign”.

Damage from a man’s or pregnant woman’s exposure to problematic chemicals can harm the reproductive health of future generations, and exposing successive generations results in cumulative damage to sperm and other markers of reproductive health. In other words, there’s a generational trickle-down effect from this damage.

These declines are largely driven by our increasing burden of chemical toxicity, which we have barely begun to address. As a result, recognition of these problems is largely unseen and solutions are unmet. Essentially chemical manufacturers and regulators continue to use consumers as guinea pigs for untested and recycled chemicals and to play the dangerous game of whack-a-mole—replacing a chemical whose harm has been exposed with a “lookalike” that has a slightly different name but similar risks (this is called “regrettable substitution”).

You’ve spent decades studying the impact of endocrine-disrupting chemicals, such as ortho-phthalates, on people. What are some of the implications of our everyday exposure to these chemicals that stand out the most to you?

The clearest damage from endocrine-disrupting chemicals, such as the phthalates and bisphenols, occurs when a pregnant woman is exposed, indirectly exposing her fetus. At this highly sensitive time, disruption to the fetus’ development is greatest and the changes that are caused are irreversible.

We often say you can’t shop your way out of the problem of toxic chemicals. There are some choices that a consumer can make but in some product categories, the least toxic products may be more expensive than what many families can afford, and for other products, there may be no safer options on the market or consumers have no way of identifying the safer options. We need governmental and corporate policy solutions that protect everyone. What role do you think the business community and government should play in safeguarding the public from hazardous chemicals?

Known endocrine disruptors must be kept out of homes and bodies completely. Before a chemical enters the marketplace, it should pass stringent requirements to ensure that it is not capable of interfering with our hormones, that it is free of low-dose adverse effects, and that is minimally environmentally persistent.