Disinfection of drinking water is vital to protect the public against disease. However disinfectants
such as chlorine react with organic matter in drinking water to produce a wide range of chemical
disinfection by-products (DBPs) of potential health concern including haloacetic acids (HAAs). This thesis is an epidemiologic analysis investigating the relationship between prenatal exposure to
HAAs in drinking water and adverse birth outcomes in “Born in Bradford”, a large multi-ethnic
prospective birth cohort study based in Bradford, England. It focuses on the understudied and as yet
unregulated HAAs which are the second most prevalent class of chlorination DBPs in UK drinking
waters. To assess exposure, area-level concentrations to three select HAAs (measured in drinking water
samples newly collected for this study, modelled in time and space, and weighted to each cohort
woman’s specific trimester of pregnancy by postcode of residence) were combined with individual
water consumption information collected via questionnaire at recruitment to the cohort. Despite the benefits of state-of-the-art exposure metrics and a large sample size, this study does not
find any significant patterns of association between prenatal exposure to HAAs and either birth
weight, being born term low birth weight or small-for-gestational age. Water consumption over the course of late pregnancy was further studied in a subset of cohort
women. A small but significant increase in water consumption was reported, bearing in mind that both
behaviour change over the third trimester of pregnancy and measurement error likely contributed to
this effect. This research addresses some of the limitations of previous DBP studies in terms of exposure
assessment and birth outcome definitions, and uniquely evaluates the variability of individual water
consumption over time. It also identifies areas for future research and examines the importance of
HAAs and birth weight-based outcomes in the larger research context.