Approximately 1 in 5 pregnancies end in a miscarriage. Alcohol use is one factor that is believed to influence miscarriage, but the relationship is still not clearly understood.
One of the reasons for the lack of a clear association between alcohol use during pregnancy and miscarriage is that researchers have taken many different approaches to looking at the issue: comparing no alcohol use at all to any alcohol use; looking only at binge drinking; looking at volume or frequency of use; or looking at type of alcohol (i.e., beer, wine, spirits).
It also appears that alcohol might have a greater impact at different stages of a pregnancy. For example, a 2012 study looking at women in the Danish National Birth Cohort (n=92 719) found that low amounts of alcohol consumption during early pregnancy increased the risk of miscarriage substantially, but that there was no increased risk after 16 weeks of pregnancy.
Similarly, a recent study (2014) by Lyndsay Ammon Avalos and colleagues in the United States found that the association between alcohol intake during pregnancy and miscarriage was strongest for miscarriage occurring prior to 10 weeks of gestation. In this study, the researchers found that there was a significant risk of miscarriage for women who drank four or more drinks a week. They also found that women who drank only spirits had more than a two-fold increased risk of miscarriage compared to women who didn’t drink at all – suggesting that the type of alcohol might also influence risk.
Overall, while some studies have been unable to show any increase in risk of miscarriage in women who drink “lightly” during pregnancy, the research evidence is not clear on what a safe threshold of alcohol consumption might be. And recent research suggests that the relationship might be more complicated than how much a women drinks – other factors such as type of alcohol and stage of pregnancy may also have a role. This body of research on miscarriage and alcohol use during pregnancy suggests that it is safest not to drink alcohol during pregnancy.
Andersen, A.N., Andersen, P.K., Olsen, J., Grønbæk, M., and Strandberg-Larsen, K. (2012). Moderate alcohol intake during pregnancy and risk of fetal death. International Journal of Epidemiology, 41(2):405-13. DOI:10.1093/ije/dyr189 (Open Access)
Avalos, L.A., Roberts, S.C.M., Kaskutas, L., Block, G., and Li, D. (2014). Volume and Type of Alcohol During Early Pregnancy and the Risk of Miscarriage. Substance Use & Misuse, Early Online:1–9. DOI: 10.3109/10826084.2014.912228. View abstract here.