This prospective cohort study (ECHO, n=5,318 US mother-child pairs, 2000–2021) measured 113 urinary analytes from 10 chemical classes at mid-pregnancy (median 25 weeks) and evaluated associations with gestational age at birth and birth weight-for-gestational age (BW-GA) z scores, including preterm birth and small for gestational age (SGA) as secondary outcomes.
Multiple phthalate/alternative plasticizer metabolites were linked to shorter gestation — e.g., summed DiNP metabolites associated with −0.6 days gestational age (95% CI −1.0 to −0.1) and preterm birth OR 1.16 (95% CI 1.01–1.34). PAHs and halogenated phenols were tied to lower BW-GA z scores — e.g., PHEN1/PHEN9 associated with −0.04 z score (95% CI −0.08 to −0.01) and SGA OR 1.13 (95% CI 1.01–1.27). 43 of 113 analytes were detected in ≥50% of samples; median woman had 45 analytes detected.
- A single mid-pregnancy urine sample was used; short biological half-lives mean one sample may not reflect full gestational exposure, likely attenuating effect estimates. - Site selection for urine submission was not random (budget-driven), and the sample skewed toward college-educated participants (67%), limiting generalizability. - Single-chemical models cannot fully account for correlated co-exposures, despite sensitivity analyses with class-level sums.
Counsel pregnant patients to minimize avoidable exposures to phthalate-containing products (plastics, personal care items) and PAH sources (traffic pollution, grilled/smoked meats), as even small reductions may yield meaningful population-level improvements in preterm birth and fetal growth. Clinicians should be aware that "replacement" chemicals (e.g., DiNCH, bisphenol F, bisphenol S) show similar adverse associations and are not clearly safer alternatives.
