A new, large study has shed light on just how many chemicals pregnant people in the US are exposed to—and the effect these chemicals may have on birth outcomes.
The study is based on samples from the National Institutes of Health’s Environmental influences on Child Health Outcomes (ECHO) Program (JAMA Network Open 2026, DOI: 10.1001/jamanetworkopen.2026.18883). A large consortium of researchers analyzed 5,318 urine samples, mostly from people in the second trimester of pregnancy, and looked for 113 substances from 10 common classes of chemicals. The 10 classes were fungicides and herbicides, insecticides, halogenated phenols, organophosphate esters, benzophenones, bisphenols, parabens, antimicrobials, phthalates and alternative plasticizers, and polycyclic aromatic hydrocarbons.
The team looked at how many chemicals were present in each urine sample, as well as the birth weight and gestational age for the associated infant. Out of 113 possible chemicals, the median amount detected across urine samples was 45, and some people had as many as 64 substances in their urine samples. Eight compounds were associated with earlier births, all of them phthalates and alternative plasticizers.
Crucially, some of the phthalates linked to earlier births in the study are ones that have been introduced as alternatives to older phthalates, which have been phased out of use because of similar health concerns.
“Many of these chemicals are really hard to avoid. Products are not necessarily labeled, so even though there are a few simple things that people can do to try to avoid exposures, it’s really difficult for an individual to do that,” says Jessie P. Buckley, one of the lead authors on the study, who works at Gillings School of Global Public Health, University of North Carolina at Chapel Hill.
Buckley says that while it’s difficult for individuals to avoid these chemicals, regulatory changes could have a much larger impact on wider consumer safety.
“I think it’s really important that it’s not put on a consumer. Somebody who’s pregnant has a lot to worry about all on their own,” she says.
