Moderate maternal and paternal alcohol consumption and the risk of spontaneous abortion.

Maternal alcoholism can lead to the fetal alcohol syndrome in offspring, but the effect of more moderate alcohol consumption during pregnancy remains an issue of concern. Therefore, we analyzed data from a large case-control study of spontaneous abortion (626 cases, 1,300 controls) that ascertained maternal alcohol consumption before and during pregnancy, as well as paternal consumption. Asking when in pregnancy alcohol consumption changed allowed us to calculate a weighted average of the amount consumed weekly during the first trimester. The odds ratio for consumption of seven or more drinks per week was 1.9 [95% confidence interval (CI) = 1.1-3.4] when adjusted for maternal smoking, passive smoking, and maternal age. Data were too sparse to examine higher consumption levels. There was some evidence that cases may have had less opportunity than controls to decrease consumption during their shorter pregnancies, potentially biasing the odds ratio upward. The adjusted odds ratio for any paternal alcohol consumption was 1.2 (CI = 0.93-1.5), with no dose-response effect seen. Among pregnancies in which the mother did not drink, there was no association with paternal drinking.