Prenatal Exposure to Compliant Nitrate in Iowa Public Drinking Water (1983-1988)

The study examined the impact of prenatal nitrate exposure on birth outcomes in Iowa, a state with intensive agricultural practices. The research included 113,328 births and analyzed nitrate exposure during the first trimester of pregnancy using data from public water systems. Findings showed that exposure to nitrate levels of 5 mg/L or higher was associated with a 1.04 percentage-point increase in preterm birth probability (13.5% relative increase) and a 0.53 percentage-point increase in very preterm birth (46.2% relative increase). Exposure between 0.1 and 5 mg/L was not associated with any adverse outcomes. The current regulatory limit is 10 mg/L, but these findings suggest a need to reassess the protection of pregnant women's and children's health.