A PROSPECTIVE-STUDY OF SPONTANEOUS-ABORTION - RELATION TO AMOUNT AND SOURCE OF DRINKING-WATER CONSUMED IN EARLY-PREGNANCY

In 1992, we published four retrospective studies, conducted primarily within a single California county, which found higher spontaneous abor tion rates among women who drank more tapwater than bottled water in e arly pregnancy. The current prospective study extends that investigati on to other water systems. Pregnant women from three regions in Califo rnia were interviewed during their first trimester. Multivariate analy ses modeled the amount and type of water consumed at 8 weeks' gestatio n in each region in relation to spontaneous abortion rate. In Region I , which was within the previous study area, the adjusted odds ratio (O R) comparing high (greater than or equal to 6 glasses per day) consump tion of cold tapwater with none was 2.17 [95% confidence interval (CI) = 1.22-3.87]. Furthermore, when women with high cold tapwater and no bottled water consumption were compared with those with high bottled w ater and no cold tapwater consumption, the adjusted odds ratio was 4.5 8 (95% CI = 1.97-10.64). Conversely, women with high bottled water con sumption and no tapwater had a reduced rate of spontaneous abortion co mpared with those drinking tapwater and no bottled water (adjusted OR = 0.22; 95% CI = 0.09-0.51). Neither tap nor bottled water consumption altered the risk of spontaneous abortion in Regions II and III. Altho ugh controlling for age, prior spontaneous abortion, race, gestational age at interview, and weight somewhat strengthened the association in Region I, the distribution of these confounders did not vary apprecia bly across regions. This study confirms the association between cold t apwater and spontaneous abortion first seen in this county in 1980. If causal, the agent(s) is not ubiquitous but is likely to have been pre sent in Region I for some time.