Nitrate in Drinking Water during Pregnancy and sPTM

To investigate the association between elevated nitrate in drinking water and spontaneous preterm birth, A within-mother retrospective cohort study of births in California ( screened 6 million birth certificate records from 2000-2011 and constructed an investigation set with ~ 1.4M consecutive sibling births ) was conducted. The public water system monitoring records to estimate nitrate concentrations in drinking water for each woman's residence during gestation were used for the association study. Two conditional logistic regression models were estimated for the odds of preterm birth at 20-31 and 32-36 wk, respectively.