Association between maternal alcohol consumption during pregnancy and risk of preterm delivery: the Japan Environment and Children's Study

Objective: To examine the association between maternal alcohol consumption during pregnancy and the risk of preterm delivery. Design: Prospective cohort study. Setting: The Japan Environment and Children's Study (JECS). Population: A total of 94 349 singleton pregnancies. Methods: Participants completed questionnaires detailing alcohol consumption during the first trimester and during the second and third trimesters. Participants were divided into four categories according to alcohol consumption (non-drinkers, consumers of 1–149 g, 150–299 g and ≥300 g ethanol/week). We examined the effect of alcohol consumption during different stages of pregnancy on the risk of preterm delivery. Odds ratios (OR) and 95% CI were calculated relative to non-drinkers using logistic regression. Main outcome measures: Medical record-based preterm delivery. Results: Alcohol consumption during the second and third trimesters, but not during the first trimester, was associated with increased risk of preterm delivery. Heavy alcohol consumption (≥300 g ethanol/week) during the second and third trimesters was associated with a four-fold higher risk compared with non-drinkers (multivariable OR 4.52; 95% CI 1.68–12.2). Light alcohol consumption (1–149 g ethanol/week) tended to be associated with lower risk of preterm delivery (multivariable OR 0.78; 95% CI 0.60–1.00). Conclusions: Heavy alcohol consumption during the second and third trimesters was associated with increased risk of preterm delivery among pregnant women. Tweetable abstract: Heavy drinking during pregnancy may increase the risk of preterm delivery.