Certain molds that grow on crops can leave behind chemicals in foods made with corn, wheat and other grains. A small New Jersey study found signs of these contaminants in urine samples from 33 pregnant women, with higher levels generally appearing after participants ate corn and grain products.
The finding, published in the Journal of Exposure Science & Environmental Epidemiology, does not mean those foods harmed the women or their babies. Researchers did not measure pregnancy complications or child development, and they did not determine whether the amounts detected were dangerous. Instead, the pilot study was an early effort to understand how pregnant women may be exposed through food.
The researchers focused on zearalenone, a substance produced by certain molds that can contaminate crops such as corn, wheat and oats. It can act somewhat like estrogen in the body, which has raised questions about whether exposure during pregnancy could affect mothers or developing babies.
Most of what scientists know about those possible effects comes from animal and laboratory studies. Evidence in people remains limited.
“Mycoestrogens are among the most common food contaminants worldwide, yet evidence on their dietary sources in the United States has been limited,” said lead author Zorimar Rivera-Núñez, an assistant professor at the Rutgers School of Public Health. “They have potent estrogenic properties, but we know very little about how these exposures may affect pregnant women and their developing babies.”
Researchers recruited 33 pregnant women from two medical centers in New Brunswick, New Jersey. At three points during pregnancy, participants provided urine samples and described everything they had eaten during the previous 24 hours.
That allowed the team to compare recent food choices with signs of exposure found in the urine.
At least one mold-related compound was detected in every sample. Zearalenone-related compounds were found in most samples and remained fairly steady for some participants across pregnancy.
Those results suggest exposure may be common and ongoing, but detection alone does not mean the amount was harmful. Modern laboratory tests can find very small traces of chemicals, and the study did not compare participants’ levels with a known danger threshold.
Corn and other grain products showed the strongest links with higher exposure. Foods reported by participants included corn, corn chips and corn tortillas.
“Our findings confirm that grain-based foods are important contributors to mycoestrogen exposure among pregnant women in the U.S.,” Rivera-Núñez said.
That conclusion should be viewed cautiously because the study was so small. It also does not mean all corn or grain products carry the same amount of contamination.
Levels can vary depending on weather, growing conditions, crop storage, processing and where food was produced. The study also could not identify which particular product or brand was responsible for an individual participant’s exposure.
Participants who identified as Hispanic had higher average levels than non-Hispanic participants and also reported eating more corn-based foods. But with only 33 people in the study, researchers could not determine whether the difference was tied to diet, particular products or other factors.
“Identifying groups with higher exposures is a critical first step for our mycoestrogen research program,” Rivera-Núñez said. “It helps us understand the factors driving those exposures and provides the information needed to develop strategies that protect maternal and child health.”
The findings do not provide a reason for pregnant people to stop eating corn, wheat, oats or other grains.
The study did not test whether avoiding those foods reduced exposure. It also did not show that washing, cooking or choosing organic products made a difference.
Consumers generally cannot tell whether a food contains a mold-related contaminant by looking at or smelling it. That means much of the responsibility falls on growers, food manufacturers and regulators to prevent contamination and monitor the food supply.
The Food and Drug Administration began including zearalenone in its human-food monitoring program in 2024. The agency has not set a maximum allowable level for zearalenone in U.S. food, though the European Union has limits for some cereals, baked goods and foods made for infants and young children.
Larger studies will be needed to determine how common these exposures are across the United States, whether certain foods or communities face higher levels and whether exposure during pregnancy affects maternal or child health.
The research was supported by the Rutgers Center for Environmental Exposures and Disease and grants from the National Institutes of Health. The authors reported no potential competing interests beyond noting that several researchers’ work on mycoestrogens has received NIH funding.