Forever Chemicals in Pregnancy Tied to Higher Gestational Diabetes Risk, Vitamin D May Blunt the Effect

A new study from China adds to mounting evidence that the so-called forever chemicals pervading modern life may interfere with one of the most delicate metabolic balancing acts in human biology: the glucose regulation that sustains a healthy pregnancy. Researchers following a prospective birth cohort in Henan Province report that pregnant women with higher blood concentrations of certain per- and polyfluoroalkyl substances, or PFAS, faced measurably higher odds of developing gestational diabetes mellitus, a condition that affects millions of pregnancies worldwide each year and can leave lasting metabolic fingerprints on both mother and child. The findings, published in the journal Environmental Health, also point to a striking and potentially modifiable factor that appears to shape this risk: the mother’s vitamin D status.

The research team, led by Liuqiao Sun and Yuting Gong of Zhengzhou University’s College of Public Health together with colleagues at the Third Affiliated Hospital of Zhengzhou University, recruited 746 pregnant women and tracked them through gestation. Each participant underwent an oral glucose tolerance test, the standard diagnostic challenge in which blood sugar is measured after a fasting period and again after consuming a standardized glucose load. Using this test, the investigators diagnosed gestational diabetes and further classified it into three clinically distinct subtypes: isolated fasting hyperglycemia, in which only the fasting measurement is abnormal; isolated postprandial hyperglycemia, in which only the after-meal measurement is abnormal; and combined hyperglycemia, in which both readings fail. This subtype-level detail matters, because the different patterns of glucose intolerance reflect different underlying physiology and may respond differently to environmental insults.

PFAS are a sprawling family of synthetic chemicals prized for their ability to repel water, grease, and stains. They coat nonstick cookware, waterproof clothing, food packaging, carpets, and countless industrial products, and their carbon-fluorine bonds are among the strongest in organic chemistry, which makes them extraordinarily resistant to degradation. That durability has earned them the nickname forever chemicals, and it also explains why they are now found in the blood of nearly everyone on the planet. PFAS cross the placenta, and previous research has suggested they can disrupt glucose homeostasis by inducing oxidative stress, provoking inflammatory responses, and interfering with endocrine signaling, the hormonal communication network that governs metabolism. Yet studies of PFAS and gestational diabetes have produced inconsistent results, and the question of whether nutritional factors might buffer or amplify the harm has remained open.

In the Henan cohort, the researchers focused on eight PFAS compounds with detection rates above 80 percent, ensuring that the statistical analysis was built on chemicals genuinely present in most participants rather than on sporadic readings. Of the 746 women, 183, or 24.53 percent, developed gestational diabetes, a prevalence that underscores the scale of the problem in this population. When the team examined individual compounds using logistic regression, three emerged as significant culprits. Higher concentrations of perfluorohexane sulfonate, abbreviated PFHpS, were associated with a 19 percent increase in the odds of gestational diabetes per unit increase in exposure, with an odds ratio of 1.19 and a 95 percent confidence interval of 1.07 to 1.32. Perfluoropentane sulfonate, or PFPeS, showed an even stronger association, with an odds ratio of 1.23 and a confidence interval of 1.09 to 1.38. Perfluorohexanoic acid, PFHxA, was also positively associated, with an odds ratio of 1.13 and a confidence interval of 1.02 to 1.25.

The subtype analysis delivered one of the study’s most intriguing findings. When gestational diabetes was broken down into its component patterns, the positive associations of PFHpS and PFPeS were confined to women with isolated postprandial hyperglycemia, the form in which blood sugar spikes specifically after meals. This pattern suggests that PFAS exposure may preferentially impair the body’s ability to clear a glucose load, a process that depends on insulin secretion from pancreatic beta cells and the sensitivity of muscle and liver tissue to insulin’s signal. Postprandial hyperglycemia is often considered a marker of early or subtle metabolic dysfunction, and the idea that endocrine-disrupting chemicals might push women over the edge specifically at this vulnerable point is biologically plausible, though the authors are careful to frame it as an association rather than proof of mechanism.

Because humans are never exposed to a single chemical in isolation, the team also employed weighted quantile sum regression, a statistical technique designed to estimate the combined effect of a mixture of exposures while identifying which components contribute most to the overall signal. The WQS analysis showed that the PFAS mixture as a whole was positively associated with gestational diabetes risk, with an odds ratio of 1.50 and a 95 percent confidence interval of 1.04 to 2.16, meaning women with higher overall PFAS burdens had roughly one and a half times the odds of developing the condition compared with those at the lower end of the mixture distribution. Within that mixture, PFHpS stood out as the top contributor, reinforcing the compound-level findings and highlighting this shorter-chain sulfonate as a chemical deserving of closer scrutiny.

The vitamin D angle is where the study takes on its most provocative dimension. Vitamin D is best known for its role in calcium and bone metabolism, but it also influences immune function, inflammation, and insulin sensitivity, and deficiency is common among pregnant women. The researchers stratified their analysis by maternal vitamin D status and found a clear divergence. Among women classified as vitamin D deficient, PFOS, PFHpS, and PFPeS were all positively associated with gestational diabetes, with odds ratios of 1.12, 1.22, and 1.26 respectively, and confidence intervals excluding the null value. Among women who were not deficient, these associations disappeared. In other words, adequate vitamin D appeared to accompany an absence of the measurable link between PFAS exposure and gestational diabetes in this cohort, hinting that nutritional status might modify the toxicity of these chemicals.

The authors themselves urge caution on this point, and for good reason. The subgroup of vitamin D non-deficient women was small, which limits the statistical power of the stratified comparison and makes the apparent protective pattern vulnerable to chance. Effect modification analyses of this kind generate hypotheses rather than definitive conclusions, and the observational design of the study means that vitamin D status may be a marker of other characteristics, such as diet, sunlight exposure, or overall health, that independently influence both chemical burdens and diabetes risk. Randomized trials of vitamin D supplementation in highly exposed populations would be needed before any recommendation could be made, though the possibility that an inexpensive, widely available nutrient could mitigate the metabolic effects of ubiquitous pollutants is certainly worth pursuing.

Even with those caveats, the study strengthens a growing body of evidence that PFAS are not passive passengers in the pregnant body but active metabolic disruptors. Gestational diabetes carries consequences well beyond the pregnancy itself: it raises the risk of preeclampsia, cesarean delivery, and birth complications, and it markedly increases the mother’s lifetime risk of type 2 diabetes. Children exposed to hyperglycemia in utero face elevated risks of obesity and metabolic disease later in life. If environmental chemicals contribute to this cascade, then reducing exposure during pregnancy becomes a public health priority, whether through regulation of PFAS in consumer products and drinking water or through clinical guidance for expectant mothers.

The Henan findings also carry a message for the chemical industry and regulators alike. Several of the compounds most strongly linked to gestational diabetes in this study, including PFHpS and PFPeS, are shorter-chain alternatives that were introduced as replacements for the long-chain PFAS phased out under international pressure. The implication that these substitutes may carry their own metabolic risks echoes a broader concern in toxicology: that regrettable substitution, swapping one persistent chemical for a structurally similar cousin, merely relocates the problem. As monitoring expands and cohorts like this one mature, the accumulating data will help determine whether the forever chemicals and their successors belong on the list of modifiable risk factors for one of pregnancy’s most common complications, and whether something as simple as correcting a vitamin deficiency might offer a measure of protection while the broader cleanup proceeds.

Subject of Research: Associations between prenatal PFAS exposure, gestational diabetes mellitus risk and its subtypes, and effect modification by maternal vitamin D status

Article Title: Associations of per- and polyfluoroalkyl substances exposure with gestational diabetes mellitus and effect modification by vitamin D status

Article References: Sun, L., Gong, Y., Cui, L., Li, F., Sun, Z., Zheng, L., Liu, Y., Cheng, M., Yuan, Y., Duan, G., Yu, Z., Chang, H., & Zhao, X. (2026). Associations of per- and polyfluoroalkyl substances exposure with gestational diabetes mellitus and effect modification by vitamin D status. Environmental Health. https://doi.org/10.1186/s12940-026-01342-3

Image Credits: AI Generated

DOI: 10.1186/s12940-026-01342-3

Keywords: PFAS, forever chemicals, gestational diabetes mellitus, pregnancy, vitamin D, endocrine disruptors, birth cohort, glucose metabolism, PFHpS, PFOS, weighted quantile sum regression, environmental health