Gestational Chemical Exposures Threaten Healthy Deliveries: JAMA

The multi-center study recruited a substantial sample of 5,318 mother-child pairs between January 1, 2000, and December 31, 2021, after which statistical analyses were conducted between January 2024 and February 2026. Single midgestation urine samples were obtained with a median of 25 weeks, ranging from 21 to 30 weeks in order to evaluate 113 distinct compounds falling into 10 different chemical groups in terms of concentrations.

In particular, these groups consisted of 11 fungicides and herbicides, 20 insecticides, 5 halogenated phenols, 10 organophosphate esters, 6 benzophenones, 14 bisphenols, 6 parabens, 2 antimicrobials, 32 phthalates or alternative plasticizers, and 7 polycyclic aromatic hydrocarbons. Linear mixed-effects regression modeling was used by the statistical team in order to calculate differences in gestational age at birth and birth weight-for-gestational age z scores per IQR change in urinary analyte concentrations as well as odds ratios for preterm birth and small for gestational age outcomes.

Key findings:

• Of the total number of 5,318 mother-infant dyads assessed, the infant group included an equal share of female participants totalling 2,667 infants with a median baseline gestational age at birth of 39.0 weeks.
• In terms of the maternal demographics, 67%, or 3,218 out of 4,785 mothers, were college educated, 56%, or 2,815 of 5,007 mothers, were multiparous, and had a median delivery age of 30.7 years.
• Of the total sample size, there were 43 out of 113 measured analytes, or 38%, which were found in 50% or more of the collected urine samples.
• Analyzing particular classes, multiple phthalates or plasticizers were found to be correlated with lower gestational ages or lower birth weight for gestational age z scores.
• In particular, summed diisononyl phthalate metabolites were significantly associated with a 0.6-day younger gestational age at delivery, with a 95% confidence interval of −1.0 to −0.1 day, which is reflected in an increased odds ratio for preterm birth of 1.16.
• Also, summed total phthalates or alternatives were significantly associated with a 0.06 lower birth weight-for-gestational age z score, which was related to an increased odds ratio for small for gestational age of 1.09.
• Moreover, two independent halogenated phenols, benzophenone 8, bisphenol F, and several polycyclic aromatic hydrocarbons have been found to be associated with a lower birth weight-for-gestational age z score.
• For example, the polycyclic aromatic hydrocarbon metabolites 1- and 9-hydroxyphenanthrene were associated with a 0.04 lower birth weight-for-gestational age z score and hence increased odds ratio for small for gestational age of 1.13.

In summary, this large-cohort study on US pregnancies of diverse background identified extensive exposure to 10 classes of environmental chemicals, with most being linked with variations in the gestational age of birth or z scores for birth weight for gestational age. This shows that limiting exposure during gestation to chemicals, especially phthalates or alternative plasticizers and PAHs, can contribute to healthy births and development of children. The impressive statistical findings over many years serve as an essential empirical basis for contemporary perinatology since fetal health cannot be maximized without addressing the issue of chemical pollution in the contemporary environment.

Reference:

Buckley JP, Pacyga DC, Xun X, et al. Gestational Exposure to 10 Classes of Priority Chemicals and Birth Outcomes in the ECHO Cohort. JAMA Netw Open. 2026;9(6):e2618883. doi:10.1001/jamanetworkopen.2026.18883