Blood Biomarkers of Late Pregnancy Exposure to Trihalomethanes in Drinking Water and Fetal Growth Measures and Gestational Age in a Chinese Cohort

BACKGROUND: Previous studies have suggested that elevated exposure to disinfection by-products (DBPs) in drinking water during gestation may result in adverse birth outcomes. However, the findings of these studies remain inconclusive. OBJECTIVE: The purpose of our study was to examine the association between blood biomarkers of late pregnancy exposure to trihalomethanes (THMs) in drinking water and fetal growth and gestational age. METHODS: We recruited 1,184 pregnant women between 2011 and 2013 in Wuhan and Xiaogan City, Hubei, China. Maternal blood THM concentrations, including chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM), were measured as exposure biomarkers during late pregnancy. We estimated associations with gestational age and fetal growth indicators [birth weight, birth length, and small for gestational age (SGA)]. RESULTS: Total THMs (TTHMs; sum of TCM, BDCM, DBCM, and TBM) were associated with lower mean birth weight (-60.9 g; 95% CI: -116.2, -5.6 for the highest vs. lowest tertile; p for trend = 0.03), and BDCM and DBCM exposures were associated with smaller birth length (e.g., -0.20 cm; 95% CI: -0.37, -0.04 for the highest vs. lowest tertile of DBCM; p for trend = 0.02). SGA was increased in association with the second and third tertiles of TTHMs (OR = 2.91; 95% CI: 1.32, 6.42 and OR = 2.25; 95% CI: 1.01, 5.03; p for trend = 0.08). CONCLUSIONS: Our results suggested that elevated maternal THM exposure may adversely affect fetal growth.