Trihalomethanes in public water supplies and adverse birth outcomes

We conducted a retrospective cohort study to evaluate the relation between the level of total trihalomethanes in drinking water and adverse birth outc omes. The study population comprised women residing in an area with municip al surface water who had a singleton birth in Nova Scotia between January 1 , 1988, and December 31, 1995, or a pregnancy termination for a major fetal anomaly. We found little association between trihalomethane level and the outcomes related to fetal weight or gestational age, but we found an elevat ed relative risk for stillbirths for average trihalomethane levels during p regnancy of 100 mu g/liter or greater (adjusted relative risk = 1.66; 95% c onfidence interval = 1.09-2.52) relative to women exposed to trihalomethane levels of 0-49 mu g/liter. We saw little evidence of an elevated prevalenc e or dose response pattern for congenital anomalies, with the possible exce ption of chromosomal abnormalities (adjusted prevalence ratio = 1.38 and 95 % confidence interval = 0.73-2.59 for women exposed to trihalomethane level s of 100 mu g/liter or greater).