1. ^aDepartment of Epidemiology, School of Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
2. ^bDepartment of Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
3. ^cDepartment of Biostatistics, School of Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
4. ^dDepartment of Community and Preventive Medicine, Mount Sinai School of Medicine, New York, New York, USA
5. ^eDepartment of Epidemiology and Public Health, Imperial College, London, UK
6. ^fUS EPA, National Center for Environmental Assessment, Cincinnati, Ohio, USA
7. ^gDepartment of Environmental Science and Engineering, School of Public Health, University of North Carolina, Chapel Hill, North Carolina, USA

Correspondence: Dr. U.M. Forssén, Department of Epidemiology, School of Public Health, CB# 8050, University of North Carolina, Chapel Hill, NC, 27599-8050, USA. Tel.: +1-919-966-1610. E-mail: ulla_forssen@unc.edu

Received 21 September 2005; Revised 21 March 2006; Accepted 22 March 2006; Published online 3 May 2006.

Abstract

Disinfection by-products (DBPs) in drinking water may be associated with adverse pregnancy outcomes. However, the results from previous epidemiological studies are not consistent, perhaps in part due to individual variation in water use and consumption. This study was performed to evaluate and describe demographic and behavioral characteristics as predictors of ingested water, showering, bathing, and swimming among pregnant women. Water use and consumption data were collected through telephone interviews with 2297 pregnant women from three geographical sites in the southern United States. The data were analyzed according to demographic, health, and behavioral variables expected to be predictors of water use and thus potential confounding factors relating water use to pregnancy outcome. The candidate predictors were evaluated using backward elimination in regression models. Demographic variables tended to be more strongly predictive of the use and consumption of water than health and behavior-related factors. Non-Hispanic white women drank 0.4 (95% confidence interval (CI) 0.2; 0.7) liters more cold tap water per day than Hispanic women and 0.3 (95% CI 0.1; 0.4) liters more than non-Hispanic black women. Non-Hispanic white women also reported drinking a higher proportion of filtered tap water, whereas Hispanic women replaced more of their tap water with bottled water. Lower socioeconomic groups reported spending a longer time showering and bathing, but were less likely to use swimming pools. The results of this study should help researchers to anticipate and better control for confounding and misclassification in studies of exposure to DBPs and pregnancy outcomes.