The Fertility Collapse: Are Chemicals Rewriting Human Reproduction?

The Question

Here is the specific prediction we are evaluating: by 2035, the human fertility decline linked to hormone-disrupting chemicals will be formally declared a public health emergency by the WHO or an equivalent international body — triggering coordinated restrictions on the worst offending chemicals across at least 30 countries. Our model gives this a 66% probability. The trend driving it has been documented for decades. Action, so far, has been almost nonexistent.

In 2021, scientist Shanna Swan published a landmark study drawing on data from over 40,000 men. The finding: sperm counts in Western men fell 59% between 1973 and 2018. At the same rate of decline, the median sperm count approaches zero around 2045. The book got two weeks of coverage. Then the world moved on. Meanwhile, South Korea's birth rate dropped to 0.72 children per woman in 2023 — less than half the level needed to maintain a stable population. Wealthy countries are running out of babies. Chemicals in the everyday products around you may be a significant part of why.

What the Evidence Shows

Phthalates are plasticisers — chemicals that make plastic flexible. They are in food packaging, shampoo, flooring, and medical tubing. Multiple studies link them to lower testosterone and disrupted development of the male reproductive system. BPA, found in hard plastics and tin-can linings, was partially restricted after evidence of harm. The industry replaced it with similar compounds — BPS and BPF — that appear to cause the same problems. Scientists call this "regrettable substitution." Meet the new chemical, same as the old chemical.

PFAS are a family of chemicals used in non-stick pans, waterproof clothing, food wrappers, and firefighting foam. They are nicknamed "forever chemicals" because they never break down — in the environment or in your body. The US CDC found PFAS in the blood of 97% of Americans tested, with the highest levels in children. Research links them to reduced fertility in women, lower testosterone in men, and disrupted thyroid function. They are also in breast milk and umbilical cord blood. Exposure begins before birth.

For women, endometriosis — a condition where tissue similar to the uterine lining grows in the wrong places — affects roughly 1 in 10 women and is a leading cause of infertility. Environmental chemicals including PFAS have been linked to its development. The demand for IVF — in vitro fertilisation, where eggs and sperm are combined in a lab — is growing roughly 10% per year globally. That figure is partly a triumph of medicine. It is also a signal that something has gone seriously wrong with the baseline conditions for natural reproduction.

Why This Is Happening

The demographic consequences are already here. Sub-replacement fertility — where a population has fewer than 2.1 children per woman — shrinks workforces, hollows out tax bases, and strains pension systems. Japan already sells more adult nappies than infant ones. South Korea, most of Southern Europe, and China are heading the same way. No government has yet found a policy that reliably reverses the trend.

The IVF industry is booming — and nobody is asking why. Global IVF revenue topped $25 billion in 2024. It is projected to hit $50 billion by 2030. Countries including France, Denmark, and Israel now subsidise multiple rounds through public healthcare. Normalising assisted reproduction is in some ways a medical triumph. But treating infertility without asking what is causing it is, at minimum, incomplete medicine.

Regulation has been shockingly slow. The EU has moved faster than the US, but still lags the pace of chemical proliferation. US law actually places the burden of proving harm on regulators — not on the companies selling the chemicals. The EPA designated a handful of PFAS as hazardous in 2024. There are over 12,000 PFAS compounds in commercial use. Most remain untouched.

What Could Happen

What Can We Do

You can't undo the chemicals already in your body. But you can reduce ongoing exposure. Switch plastic food containers for glass or stainless steel. Avoid non-stick cookware. Steer clear of microwave popcorn bags and fast-food wrappers — both are coated in PFAS. Choose fragrance-free personal care products, which are a major source of phthalate exposure. These steps matter most during pregnancy and in the years before it, when the reproductive system is most sensitive to chemical interference.

If you are struggling to conceive, investigate early rather than waiting. Endometriosis is frequently diagnosed seven to ten years after symptoms begin, because painful periods are too often dismissed as normal. A semen analysis is quick, cheap, and often the last thing a couple thinks to do — yet male factors account for about 40% of infertility cases. Knowing the cause quickly means better treatment and sometimes reveals modifiable factors, including chemical exposures at work.

At the political level, the most important change is reforming how new chemicals get approved. Right now, companies can introduce chemicals without proving they are safe first. Regulators have to prove harm after the fact — with limited budgets and years of delay. Flipping that burden of proof, and applying it specifically to chemicals that end up in food, water, and personal care products, is the single most powerful step available. Whether that happens before the biological damage becomes permanent is the question our 66% is tracking.