Drinking Water Disinfection By-Product Exposure and Fetal Growth

Background: Previous studies suggest that elevated exposure to drinking water disinfection by-products (DBPs)—in particular, total trihalomethanes (TTHMs)—may lead to fetal growth restriction. We examined the effects of exposure to TTHMs, haloacetic acids, and total organic halide on the probability of delivering a small-for-gestational-age (SGA) infant and on birth weight at term. Methods: Women early in pregnancy (≤12 weeks' gestation) or planning a pregnancy were enrolled in a prospective pregnancy study conducted in 3 US communities from 2000 through 2004. Weekly (or biweekly) water samples were collected at each site as well as individual-level participant data. Associations between DBP exposures (TTHMs, haloacetic acids, total organic halide) and fetal growth were assessed using log-binomial regression for SGA (n = 1958) and linear regression for term birth weight (n = 1854). We conducted a Bayesian analysis to examine associations between individual DBP species and fetal growth. Results: Haloacetic acids and total organic halide were not associated with SGA or term birth weight. The probability of delivering an SGA infant was elevated when comparing women with an average third-trimester residential TTHM concentration ≥80 μg/L to women with exposure