Background: Controversies still exist regarding the existence of a 'safe' level of alcohol intake during pregnancy. The aim of this study was to assess the risk of fetal death (spontaneous abortion and stillbirth) according to maternal alcohol consumption in a large Danish pregnancy cohort.
Methods: A cohort study carried out within the framework of the Danish National Birth Cohort. A total of the 92 719 participants enrolled in the Danish National Birth Cohort who provided information about lifestyle during first trimester of pregnancy were included in the study. Information about average weekly consumption of alcohol during pregnancy, smoking, coffee drinking, occupational status and reproductive history were obtained by means of computer-assisted telephone interviews. Pregnancy outcomes (spontaneous abortion, stillbirth, live birth and other pregnancy outcome) and gestational age at end of pregnancy were obtained through register linkage with the Civil Registration System and the National Discharge Registry. Data were analysed using Cox regression models, taking the varying gestational age at recruitment and time-dependent co-variables into account.
Results: Fifty-five per cent of the participants abstained from alcohol drinking during pregnancy and only 2.2% reported four or more drinks per week. The adjusted hazard ratios for fetal death in first trimester were 1.66 [95% confidence interval (CI) 1.43-1.92] and 2.82 (95% CI 2.27-3.49) for women who reported 2-3½; drinks per week and 4 or more drinks per week, respectively, and 1.57 (95% CI 1.30-1.90) and 1.73 (95% CI 1.24-2.41) for fetal death during pregnancy weeks 13-16. No increased risk was found for fetal death after 16 weeks of pregnancy.
Conclusions: Even low amounts of alcohol consumption during early pregnancy increased the risk of spontaneous abortion substantially. The results indicate that the fetus is particularly susceptible to alcohol exposure early in pregnancy.