Rethinking Pregnancy Nutrition: The Overlooked Issue of Environmental Chemical Exposure

By Irene Yeh

Eating a healthy diet during pregnancy may come with an unexpected tradeoff: some foods recommended for good nutrition can also be sources of environmental chemical exposure. The United States Dietary Guidelines for Americans (DGA) recommend that pregnant people eat more fruits, vegetables, whole grains, dairy, and protein while limiting added sugars, sodium, saturated fats, and refined grains. Yet produce can carry pesticide residues, and the convenience foods that might appeal to an exhausted pregnant woman could increase exposure to chemicals found in plastics and food packaging. 

Researchers from the National Institutes of Health-funded Environmental influences on Child Health Outcomes (ECHO) examined whether following the DGA during pregnancy was associated with exposure to more than 100 environmental chemicals, including bisphenols, phthalates, or polycyclic aromatic hydrocarbons (PHCs). They evaluated the relationship between the Healthy Eating Index (HEI) and pregnancy exposure and identified which of the HEI components were most strongly associated with chemical exposures (American Journal of Clinical Nutrition, DOI: 10.1016/j.ajcnut.2026.101393). 

Analyzing the Chemical Biomarkers  

Previous studies have indicated that foods that contain added sugars, are ultra-processed, are high in saturated fats, or are packaged in plastic or cans may increase exposure to environmental chemicals. Other research suggests that diets emphasizing fruits and vegetables may also have higher exposure to pesticides, but studies with nonpregnant adults following an organic, fresh food diet with limited intake of fast foods showed significant reduction in exposure to chemicals. This calls into question whether the DGA are associated with exposure to environmental chemicals during pregnancy.  

The research team initially identified 20,584 pregnant participants from 21 ECHO study sites. Of these, 6,107 participants provided urine samples that were analyzed for chemical biomarkers. Each study site selected participants for chemical assays using criteria, such as available urine volume and longitudinal follow-up, as well as complete diet data. The final analytic sample was 1,492 participants from six sites located in Northern and Southern California, Illinois, Michigan, Tennessee, and Georgia. 

The participants were identified as non-Hispanic White (40%) or Black (36%) and half of them had incomes of greater than or equal to $50,000.  Notably, the population consisted of a diverse range of ethnic and socioeconomic backgrounds. 

The research team related the self-reported dietary habits of the participants to diet quality based on how closely the participants followed the DGA. The median HEI-2015 score was 61.9 out of 100, indicating moderate adherence to the DGA overall. The participants scored highly for eating produce, protein, plant-based foods, and dairy, as well as limiting refined grains and added sugars. However, they scored lower for whole grains and healthy fatty acids and tended to consume more sodium and saturated fat than recommended.  

Those with higher HEI-2015 scores—meaning they followed DGA recommendations more closely—tended to have lower levels of several chemical biomarkers in their urine. These included chemicals from pesticides, plastics, and food packaging. These findings are consistent with previous studies of pregnant people, which also linked healthier diets or lower consumption of highly processed foods with lower exposure to certain chemicals. However, research in adults who were not pregnant did not find a clear correlation between diet quality and exposure to bisphenols, phthalates, or PAHs. 

The researchers suggest that differences in how closely people follow dietary guidelines—and therefore which foods they consume—could help explain these inconsistent findings, since some foods can be sources of chemical exposure. The analysis suggests that higher intake of protein, whole grains, vegetables, and fruit contributed to lower levels of some chemical biomarkers. The researchers note that these dietary patterns may also involve eating fewer highly processed and packaged foods, which can be sources of many of the chemicals measured in the study. 

A Healthy Diet Doesn’t Eliminate Exposure 

The study found that greater adherence to DGA was associated with lower exposure to several classes of environmental chemicals, but the relationship was not consistent across all chemicals measured. Higher HEI-2015 scores were associated with lower levels of chemicals. In secondary analyses, the team found that diets higher in protein, greens, beans, and whole fruit were top contributors to greater insecticide, benzophenone, and paraben biomarker levels. “Fresh fruits and vegetables are important for a healthy pregnancy diet, but they can also be a source of pesticides,” Diana Pacyga, ECHO researcher at the UNC Gillings School of Global Public Health, said in a press release.  

The research team noted a few limitations. First, dietary assessments differed from each study site, which means there could have been differences in how participants recalled what they ate, the time periods they reported on, and the level of detail captured about specific foods and nutrients. Though it provided a standardized way to assess overall diet quality, the HEI-2015 may not fully capture cultural or population-specific dietary patterns outside national guidelines that could influence chemical exposures. Finally, because these chemical biomarkers are typically broken down and expelled from the body within 24 to 48 hours, a single urine test could not fully capture a person’s exposure over the course of an entire pregnancy. The timing of urine collection may also not have matched when participants completed their dietary assessments.  

Jessie P. Buckley, another ECHO researcher at UNC Gillings School of Global Public Health, recommended “a modest revision of the dietary guidelines to include advice on reducing chemical exposures could help protect pregnant women’s health without changing the food recommendations we already know support good nutrition” in the same press release. While individual choices—such as thoroughly washing produce or choosing organic options when feasible—may help reduce pesticide exposure, the researchers emphasize that broader efforts to reduce contaminants throughout the food supply will ultimately be needed.