Can Chemicals in Our Environment Cause Miscarriage? What the Research Really Says

Almost everyone who has been through a pregnancy loss eventually asks some version of the same question. Was it something I was exposed to? Something I ate, something I breathed, something in the water bottle I carried to work every day for five years?

It is rarely asked out loud at the first appointment. It comes later, quietly, usually on the way out the door. And until fairly recently, the honest answer has been that nobody really knew.

A group of researchers in China set out to change that. Their review was published in 2026 in a journal called Reproductive Toxicology, which studies how chemicals affect fertility and pregnancy. Rather than running a new experiment, they gathered up the research that already existed and asked two questions. What have we actually shown so far, and where does the evidence run out?

They were especially interested in a situation many people reading this will recognise. Someone has had two or more miscarriages, has been through a full round of testing, and every result has come back normal. Doctors call this unexplained recurrent pregnancy loss. It describes roughly half of all recurrent loss cases, which means a very large number of people are sent home without an answer.

Poor Air Quality

Of everything the researchers looked at, air pollution has the most evidence behind it.

A large 2026 analysis pooled the results of thirty seven separate studies. It found that women exposed to higher levels of several common air pollutants had a higher chance of miscarriage. That included sulfur dioxide and carbon monoxide, both of which come mostly from burning fuel, along with ozone, nitrogen dioxide from traffic exhaust, and fine particles. Very hot weather showed up as a risk on its own too.

Those fine particles, often written as PM2.5, are the ones that get the most attention. They come from vehicle exhaust, industry, and wildfire smoke, and they are small enough to be breathed deep into the lungs and pass into the bloodstream. The findings here are not perfectly consistent, in some cases no link has been found.

Heavy Metals in our Environment

Lead, mercury and cadmium have been known to be hard on pregnancy for a very long time. What is newer is research looking at them specifically in women with repeated losses.

A 2023 study measured a range of metals in women who had experienced unexplained recurrent miscarriage and compared them with women who had not. The exposure patterns were different between the two groups, with lead standing out in particular. Lead can still turn up in older plumbing, some imported cosmetics and spices, and contaminated products.

Chemicals in Plastics

Bisphenol A, usually called BPA, is the one most people have already heard of. It is used to harden plastic and shows up in the lining of some tins and in till receipts.

One study in eastern China measured BPA in the urine of about a hundred women who had experienced repeated miscarriage and compared them with a control group. The women with the highest levels had notably higher odds of loss, and the pattern went in a steady line, meaning more exposure went with more risk. That said, this was one study in one population, and the samples were collected after the losses had already happened, so it cannot tell us what exposure looked like beforehand.

Phthalates are a related group. They are what make plastic soft and bendy, and they also turn up in fragrance and personal care products. A 2026 study using a large American health survey found a link between phthalates and both single and repeated pregnancy loss. Newer chemicals brought in to replace BPA, such as bisphenol F, are now being studied as well, and the early signs suggest they may not be the safer swap everyone hoped for.

The chemicals that never break down ('forever chemicals')

PFAS are the group behind non-stick pans, waterproof jackets and stain resistant fabric. They are nicknamed forever chemicals because they barely break down, either in the environment or in the body.

One study compared several hundred women with a history of pregnancy loss against women without, and found five specific PFAS compounds sitting at higher levels in the first group.

Understanding the Potential Impact of these Chemicals

The chemicals above have almost nothing in common with each other, which makes it interesting that the research keeps pointing to the same handful of biological explanations.

The main explanations of how these chemicals might negatively impact reproductive health are a kind of cellular wear and tear that damages tissue over time, changes in how the immune system responds to a pregnancy, interference with hormone signalling, and problems with the blood vessels that form the placenta. There is also evidence that some of these chemicals can change how genes are switched on and off without changing the genes themselves.

Limitations of the Current Research

This is the most important section, and it is the part the reviewers themselves stressed hardest.

Almost all of the research above studied one off miscarriage rather than repeated miscarriage. The authors were quite blunt that these two very different situations have been lumped together again and again in the literature. Evidence that applies specifically to unexplained recurrent loss is, in their words, extremely scarce.

These are also observational studies. They can show that two things tend to occur together, but they cannot prove one caused the other. Most measured exposure at a single moment in time, often after a loss. And nobody in real life is exposed to one chemical on its own. We live in mixtures, and how those mixtures behave together is barely understood.

Most importantly, there is no study showing that reducing any of these exposures lowers the chance of miscarriage. That research simply has not been done yet.

None of this is a Patient's Fault

The reviewers made a point of asking that this topic be handled gently, and they were right to.

Nothing here suggests a pregnancy loss was caused by something you did or failed to do. The air quality where you live, the water coming out of your tap, and the chemicals used to make everyday products are not personal choices. This belongs in the conversation as background, not as one more thing to feel responsible for.

If you are working through repeated losses and this has been on your mind, it is a reasonable thing to raise with a clinician who works in fertility and can help you sort what is genuinely known from what is still guesswork, and place it alongside everything else going on in your own situation.

References

Liu C, Huang J, Wang F. Environmental exposures and pregnancy loss: a critical gap analysis for unexplained recurrent pregnancy loss. Reproductive Toxicology. 2026;109341.

Angaw DA, Andargie BA, Muhumuza N, Nakanwagi G, Mulumba M. Impact of climate change on spontaneous abortion: a systematic review and meta-analysis. Frontiers in Global Women's Health. 2026;7:1709985.

Shen Y, Zheng Y, Jiang J, et al. Higher urinary bisphenol A concentration is associated with unexplained recurrent miscarriage risk: evidence from a case-control study in eastern China. PLoS ONE. 2015;10(5):e0127886.

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This article is provided for general educational purposes and is intended to raise awareness of emerging research. It does not constitute medical advice, diagnosis, or treatment, and it should not be used as a substitute for consultation with a qualified healthcare provider. Individual circumstances vary considerably, and any decisions regarding your health or fertility care should be made in partnership with a licensed clinician who is familiar with your full medical history.

About Dr. H. Singh, ND

Dr. H. Singh is a Fertility Naturopath based in Ottawa with over ten years of experience focusing exclusively on reproductive health.

He works with individuals and couples across Ontario and Quebec, supporting patients trying to conceive naturally or alongside treatments such as IUI and IVF.

Care focuses on evidence informed strategies to support egg quality, sperm health, hormonal balance, implantation, and early pregnancy.