This study, based on data from 40,892 pregnant women in Denmark evaluated the association between amount and type of alcohol consumed during pregnancy and the risk of preterm delivery. It assessed whether the relation differs among very (<32 completed weeks) and moderate (32-<37 completed weeks) preterm delivery.
Preterm birth is one of the main causes of neonatal mortality, neonatal morbidity, and functional impairments. Previous studies on alcohol consumption during pregnancy and preterm delivery have revealed conflicting results. Compared with those who abstained during pregnancy, the relative risk for preterm delivery among women who consumed from 4 to 7 drinks and seven or more drinks per week during pregnancy were 1.15 and 1.77, respectively. Below these levels, no increased risk of preterm delivery was found. Among women who consumed seven or more drinks per week, the relative risk of very preterm delivery was 3.26 compared with that of nondrinkers. There were no differences in the associations between type of beverage and preterm delivery.
The study showed that alcohol consumption below four drinks per week did not increase the risk of preterm delivery; in fact, women in this study consuming 2-3.5 drinks per week had a 20% reduction in risk of preterm delivery that was statistically significant. The estimates of risk for greater amounts of alcohol were above one, indicating some increase in risk for preterm delivery, although it should be noted that none of these estimates suggesting increased risk were statistically significant.
In the US women are generally advised to not drink at all during pregnancy, whereas in the UK one or two drinks (8g) once or twice a week are deemed safe by the government guidelines. Since there are many adverse outcomes to alcohol consumption during pregnancy, and “safe level” have not been determined for many outcomes, the present study authors state that their findings should not be used to encourage alcohol consumption during pregnancy. However, the fact that drinkers of up to 4 drinks per week did not have an adverse outcome suggests that women who have an occasional drink during pregnancy should not be concerned about increasing their risk of preterm delivery. Neither did the findings support the belief that women hoping to conceive should abstain altogether, as their findings showed women who abstained from alcohol prior to pregnancy and did not drink during pregnancy actually had a higher risk of preterm delivery than women consuming small amounts of alcohol.
Source: Albertsen K, Andersen A-M N, Olsen J, Gronbaek M. Alcohol consumption during pregnancy and the risk of preterm delivery.Am J Epidemiol 2004;159:155-161.