In more than 35 years of practicing obstetrics and gynecology, I have seen enormous advances in our ability to investigate and treat infertility. Yet we still tend to begin the fertility conversation relatively late—usually when someone is ready to conceive or has already encountered difficulty.
New research into endocrine-disrupting chemicals suggests that we need to think much earlier.
What if some influences on fertility begin not three months before conception, but before we ourselves are born? Could the chemical environment during pregnancy affect the future reproductive health of the developing child?
A new study from Denmark does not provide a definitive answer, but its findings deserve our attention.
What are endocrine-disrupting chemicals?
Our hormones function as chemical messengers. They help regulate ovulation, menstruation, sperm production, metabolism, thyroid function, pregnancy and fetal development.
Endocrine-disrupting chemicals, often shortened to EDCs, are external substances that may interfere with these hormonal signals. Depending on the chemical, they may imitate a natural hormone, block a hormone receptor, change hormone production or metabolism, or influence the genes involved in reproductive development.
They include:
- PFAS, often referred to as “forever chemicals”
- phthalates used in plastics, fragrances and personal-care products
- bisphenols such as BPA, BPS and BPF
- certain pesticides
- some flame retardants
- polychlorinated biphenyls, or PCBs
- other persistent industrial pollutants
These exposures do not usually occur one at a time. We encounter chemical mixtures through food, drinking water, packaging, cookware, household dust, personal-care products, clothing, furniture and our workplaces.
This makes the research difficult. It is relatively straightforward to study one chemical in a laboratory. It is much harder to determine the effect of many low-level exposures occurring together over years.
Newer studies are beginning to address this by examining mixtures rather than evaluating every chemical in isolation.
Could prenatal exposure affect a son’s fertility years later?
A recently published Danish study followed 841 young men whose mothers had participated in the Danish National Birth Cohort. Researchers had biological samples collected from the mothers during pregnancy and were therefore able to estimate prenatal exposure to several endocrine-disrupting chemicals.
Years later, when the sons reached young adulthood, the researchers assessed markers of reproductive health, including sperm concentration, total sperm count, sperm movement, testicular volume and reproductive hormones.[1]
They then asked whether higher exposure to the overall chemical mixture during fetal life was associated with differences in these measurements.
For every one-quartile increase in the prenatal chemical mixture, the researchers estimated approximately:
- 4 million fewer sperm per millilitre
- 16 million fewer sperm in the total ejaculate
- slightly smaller testicular volume
- a greater proportion of non-progressive or immotile sperm
- a modestly higher FSH concentration
The results appeared to be influenced more by PFAS than by the non-persistent chemicals included in the study.
Why might FSH be relevant? In a man, FSH helps regulate sperm production. A higher FSH level can sometimes represent an attempt by the pituitary gland to stimulate testicular function more strongly. In this study, however, the difference was small and cannot be interpreted as evidence of infertility in an individual participant.
There is another important limitation: most of the confidence intervals crossed the line of no effect. In plain language, the researchers could not exclude the possibility that some of the observed differences occurred by chance.
The study therefore does not prove that prenatal exposure to these chemicals causes male infertility. It also does not tell us whether the differences in semen parameters affected the young men’s ability to become fathers.
Nevertheless, it raises an important biological possibility. The male reproductive system develops through a carefully coordinated sequence of hormonal signals before birth. Interference during this sensitive developmental period could potentially have effects that are not apparent until much later.
The study’s real contribution may be the question it asks: should we view fertility as something shaped not only by our present lifestyle, but also by our earliest environment?
What about female fertility?
The same intergenerational principle may apply to women.
A female fetus begins developing her lifetime supply of eggs before she is born. This means that when a woman is pregnant with a daughter, three generations are biologically connected: the mother, the developing daughter and the germ cells that may one day contribute to the mother’s grandchildren.
This does not mean that one exposure during pregnancy will determine a daughter’s future fertility. Reproductive health is shaped by many factors, including age, genetics, medical conditions, nutrition, metabolism, environmental exposures and chance.
It does mean that fetal life is a particularly important window of development.
What have researchers found around developing eggs?
Another recent study examined women undergoing IVF or ICSI and measured multiple endocrine-disrupting chemicals directly in their follicular fluid.[2]
Follicular fluid surrounds the developing egg inside the ovarian follicle. It contains hormones, nutrients and signalling molecules that support oocyte maturation.
The presence of a chemical in follicular fluid does not automatically mean that it has harmed the egg. It does, however, demonstrate that chemicals encountered in daily life can reach the immediate environment in which an egg develops.
The researchers examined both individual chemicals and combinations of exposures. Higher concentrations of several chemicals were associated with less favourable assisted-reproduction outcomes. In the mixture analysis, phthalates and bisphenol S were among the more important contributors.
The finding involving bisphenol S is noteworthy. BPS is sometimes used to replace BPA in products marketed as “BPA-free.” Unfortunately, replacing one chemical with a structurally similar compound does not necessarily eliminate endocrine-disrupting activity.
This is sometimes called a regrettable substitution: a recognized chemical is removed, but the replacement may eventually prove to have similar biological effects.
We must still interpret the IVF findings carefully. Women undergoing fertility treatment are a selected population, and many factors influence ovarian response, embryo development and pregnancy. An association between a chemical measurement and an IVF outcome does not prove that the chemical caused that outcome.
Most importantly, a patient should never conclude that she caused an unsuccessful fertility treatment by using the wrong container, cosmetic or cleaning product.
What does the broader research show?
A 2026 systematic review brought together 38 human observational studies published between 2020 and May 2025.[3]
The researchers examined evidence involving phthalates, bisphenols, PFAS, persistent organic pollutants and heavy metals. Across these studies, greater exposure was associated with several adverse reproductive indicators, including hormonal changes, diminished ovarian reserve, altered follicular development, reduced oocyte yield and less favourable fertility-treatment outcomes.
Some patterns were more consistent than others:
- Phthalates had some of the more consistent associations with oocyte-related outcomes.
- BPA and other bisphenols were associated with hormonal abnormalities and features of PCOS, now also called PMOS.
- Certain persistent organic pollutants were associated with lower oocyte yield or poorer assisted-reproduction outcomes.
- Chemical mixtures were associated with diminished ovarian reserve in some studies.
- Evidence for individual chemicals and specific clinical outcomes remained inconsistent.
This review strengthens the argument that environmental exposures deserve a place in reproductive-health research. It does not establish that these chemicals are responsible for an individual case of infertility.
Nearly all the available human evidence is observational. We do not yet have randomized trials demonstrating that reducing a particular household exposure improves pregnancy or live-birth rates.
That is the difference between evidence of concern and proof of treatment.
What can we reasonably do?
When patients first hear about endocrine-disrupting chemicals, they may feel that they need to discard everything in their homes and attempt an expensive “detox.”
I do not believe that is either practical or helpful.
We cannot eliminate every exposure, and the responsibility for regulating potentially harmful chemicals should not rest entirely on individual consumers. At the same time, there are sensible, low-risk ways to reduce avoidable exposure.
The goal is not to create a perfectly chemical-free life. Such a life does not exist. The goal is to make a few changes that are manageable and sustainable.
Do not heat food in plastic
Heat can increase the movement of certain chemicals from plastic into food.
Use glass, ceramic or stainless steel for hot foods and drinks. Transfer food into a non-plastic container before placing it in a microwave. Avoid pouring very hot liquids into plastic containers unless they are specifically designed for that purpose.
Gradually replace damaged items
Badly scratched plastic food containers and heavily damaged non-stick cookware are reasonable priorities for replacement.
There is no need to replace everything at once. Start with the items you use most frequently, particularly those exposed to heat.
Eat more food that does not require a label
A diet emphasizing vegetables, fruit, legumes, nuts, seeds, whole grains and minimally processed sources of protein has many potential benefits before pregnancy.
It may also reduce exposure from food packaging and processing equipment. This does not require perfection. Replacing even a few frequently consumed packaged foods with simpler alternatives is a useful start.
Choose fragrance-free products when possible
The term “fragrance” can represent a mixture of ingredients, which may include phthalates.
Consider fragrance-free personal-care products, laundry products and household cleaners, particularly those used every day. Remember that “unscented” does not always mean fragrance-free; masking fragrances may have been added to cover another smell.
Be cautious about stain- and water-resistant treatments
PFAS have been used in some stain-resistant carpets and furniture, water-resistant clothing, cosmetics and grease-resistant food packaging.
When buying new products, look for a specific statement that they are PFAS-free. Broad descriptions such as “natural,” “green” or “non-toxic” do not have a consistent scientific meaning.
Reduce unnecessary contact with thermal receipts
Some thermal receipt paper contains bisphenols.
Decline receipts you do not need, choose electronic receipts when available and wash your hands before eating after handling them. This may be especially important for people who work with receipts throughout the day.
Learn about your drinking water
PFAS exposure through drinking water varies considerably by location.
Municipal water-quality reports may provide useful information. If there is a recognized local concern, look for a filter independently certified to reduce the specific contaminant. Not every filter removes PFAS, and an expensive filter is not automatically an effective one.
Consider workplace exposure
Potential occupational exposures may occur in agriculture, manufacturing, salons, cleaning, firefighting, construction, health care and industries involving plastics or solvents.
This applies to both prospective parents. Relevant exposures should be discussed with an occupational-health professional rather than managed through guesswork.
What I would not recommend
I would be cautious about commercial “toxin panels,” extreme cleanses and detoxification supplements.
Finding a substance in blood, urine or hair does not necessarily tell us whether it has caused a health problem. For short-lived chemicals, one measurement may simply reflect a recent exposure and may vary considerably from day to day.
There are also no established “optimal” fertility levels for many of the chemicals offered in commercial testing.
Detox supplements do not remove the need to identify the source of exposure, and some may be inappropriate or unsafe while trying to conceive or during pregnancy.
Concern without blame
Environmental fertility research presents us with a difficult balance. We should not dismiss the evidence simply because it is not yet perfect. Nor should we frighten patients or imply that infertility results from failing to live a sufficiently “clean” life.
Most people have had little control over the chemicals permitted in food packaging, drinking water, cosmetics, household products and workplaces. Infertility is complex, and it is rarely possible to attribute it to one exposure.
I prefer to approach this research with informed concern rather than fear.
We can take reasonable precautions while continuing to ask for better studies, safer product design, clearer labelling and stronger regulation. We can also broaden preconception care so that environmental and occupational health are discussed alongside nutrition, smoking, alcohol, medical conditions and medications.
The most important message is not that prospective parents must do everything perfectly.
It is that fertility may be influenced earlier than we once believed. Supporting reproductive health before conception—and protecting healthy development during pregnancy—may have benefits that extend beyond one pregnancy and perhaps into the next generation.
That is why earlier matters.
Dr Marina OBGYN
References
- Sidsel Dan Hull et al., “Fetal Exposure to a Mixture of Endocrine-Disrupting Chemicals and Biomarkers of Male Fecundity: A Population-Based Cohort Study,” Andrology 14, no. 1 (2026): 76–89, https://doi.org/10.1111/andr.70039.
- Yuxin Jiang et al., “Exposure to Endocrine-Disrupting Chemicals in Follicular Fluid: Implications for Assisted Reproductive Technology Outcomes,” Reproductive BioMedicine Online 52, no. 3 (2026): 105341, https://doi.org/10.1016/j.rbmo.2025.105341.
- Fatemah Sairat, Ahmed Mediani, Nor Muhammad Hilmi Hussin, Rahma Micho Widyanto, and Razinah Sharif, “Environmental Contaminants and Endocrine Disrupting Chemicals in Female Infertility: A Systematic Review,” Middle East Fertility Society Journal 31 (2026): article 4, https://doi.org/10.1186/s43043-026-00298-1.
