Drinking during pregnancy increases risk of premature birth

Drinking alcohol during pregnancy is associated with an increased risk of miscarriage, premature birth, and low birth weight. But there are conflicting reports about how much alcohol, if any, it is safe for a pregnant woman to drink. New research published in Biomed Central's open access journal BMC Pregnancy and Childbirth looked at the amounts of alcohol women drank during their early pregnancy and showed the effect this had on their babies.

Researchers in Dublin questioned more than 60,000 pregnant women during their hospital booking interview, which usually occurred 10-12 weeks after conception. The women were asked about their home life, whether they worked, what their nationality was, as well as their drinking habits prior to their antenatal booking visit. This data was compared to data from the birth record and to records from the special care baby unit.

While about a fifth of these women said that they never drank, 71% claimed to be occasional drinkers (0-5 units a week). Within this low-alcohol group there was one case of fetal alcohol syndrome, so it is likely that some of the women were underestimating (or under reporting) the amount they drank. In general, fetal alcohol syndrome occurred less frequently than expected in this study, suggesting that it is either not recognized by medical staff or only becomes apparent after the mother and baby have left the hospital.

10% of the pregnant women drank a moderate amount of alcohol (6-20 units a week). These women were more likely to smoke, be in work and to have private health care compared to those who never drank. Only 2 in 1000 admitted to being heavy drinkers (greater than 20 units per week). These women were most likely to be young and to have used illegal drugs.

The moderate and heavy drinkers were often first time mums (not surprisingly, unplanned pregnancy was associated with heavy drinking). Heavy drinking was also related to very premature birth, and hence all the problems premature babies have including the increased risk of disease as an adult. However, there was no difference in occurrence of congenital or other birth defects regardless of the amount of alcohol drunk.

Prof Murphy said, "This study emphasizes the need for improved detection of alcohol misuse in pregnancy and for early intervention in order to minimize the risks to the developing fetus. We would recommend that further research is required before even low amounts of alcohol can be considered safe."

1. Prevalence, predictors and perinatal outcomes of peri-conceptional alcohol exposure - retrospective cohort study in an urban obstetric population in Ireland
Aoife Mullally, Brian J Cleary, Joe Barry, Tom P Fahey and Deirdre J Murphy
BMC Pregnancy and Childbirth (in press)

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