Association of Brominated Trihalomethane and Haloacetic Acid Exposure with Fetal Growth and Preterm Delivery in Massachusetts

OBJECTIVES: We examined the relationship between adverse reproductive outcomes and exposure to several disinfection by-products including haloacetic acids (HAAs), trihalomethanes (THMs), and the brominated THMs sum (THMBr). METHODS: Second- and third-trimester exposure scores were estimated from quarterly town-level average THM and HAA concentration data and were examined relative to mean birth weight (BWT), small for gestational age (SGA), and preterm delivery (PTD). RESULTS: We found an increased risk of PTD for second-trimester chloroform, bromodichloromethane, and all HAA exposure metrics (adjusted odds ratio range: 1.04 to 1.15), but detected no associations for SGA and third-trimester exposures. Mean BWT deficits were observed across all HAA (26 to 33 g) and THMBr (11 to 23 g) exposure categories. CONCLUSIONS: We detected consistent associations for adjusted mean BWT and THMBr exposures; these data reinforce the need to consider different disinfection by-product exposure metrics in epidemiological studies.