Drinking early in pregnancy not associated with worse outcomes

By Anne Harding

NEW YORK (Reuters Health) - Women who drink in early pregnancy, even those who binge drink, are not at increased risk of having a premature baby, a new report suggests.

But it remains unclear whether any level of alcohol consumption is safe in pregnancy, the authors say.

"This study did not evaluate the association between alcohol consumption in pregnancy and long-term neurocognitive outcomes of children exposed as fetuses to alcohol," Dr. Fergus P. McCarthy of University College Cork and his colleagues write. "This potential for neurocognitive dysfunction remains one of the single most important reasons for pregnant women to avoid alcohol intake during pregnancy."

Up to half of women drink during pregnancy, Dr. McCarthy and his team note in the October issue of Obstetrics & Gynecology, "despite many advisory bodies recommending alcohol avoidance."

While the American College of Obstetricians and Gynecologists urges doctors to tell their pregnant patients to avoid alcohol, the UK's Royal College of Obstetricians states that there is no evidence that drinking one or two drinks once or twice a week is harmful. The scientific evidence for the risks has been mixed, the researchers add, with a recent review of the medical literature finding an increased risk of low birth weight and premature birth for women who drank more than 1.25 drinks a day.

To better understand the relationship between drinking in early pregnancy and pregnancy outcomes, Dr. McCarthy and his colleagues looked at pregnancy outcomes for 5,628 women from Ireland, the UK, Australia, and New Zealand who had been interviewed when they were 15 weeks pregnant with their first baby.

About 20% said they drank occasionally (one or two drinks a week); 25% reported low alcohol consumption (3 to 7 drinks a week); 11% moderate drinking (8 to 14 drinks per week) and 5% heavy (more than 14 drinks a week). One-third of the women reported binge drinking (having at least six drinks at one session) in the three months before their pregnancy, while 23% reported binge drinking during their first 15 weeks of pregnancy.

While the researchers had hypothesized that women who drank would be at increased risk of having a small baby or delivering prematurely, they found no association between alcohol consumption or binge drinking and these outcomes. For instance, binge drinking before pregnancy or during the first trimester was not linked with higher odds of spontaneous preterm birth (adjusted odds ratio, 0.78; 95% confidence interval, 0.33 - 1.80; and aOR, 0.90; 95% CI 0.70 -1.16, respectively).

Sixty percent of the women in the study reported drinking while they were pregnant, while 20% admitted to binge drinking, Dr. McCarthy and his team note. This is far higher than has been shown in any study from North America, where an average of 12% of women report drinking during pregnancy and 2% report binge drinking.

"This may reflect differences in patterns of alcohol consumption by young women and the varying advice on alcohol consumption while pregnant in different countries," the researchers write.

Nevertheless, they say, it is not clear that it is safe to drink at any point in pregnancy.

And most children with fetal alcohol syndrome (FAS), the most severe effect of prenatal exposure to alcohol, are not born prematurely or small for gestational age, Dr. Susan Astley, the director of the Washington State FAS Diagnostic & Prevention Network in Seattle, told Reuters Health.

The outcomes examined in the new study "are very insensitive measures of the adverse impacts of prenatal alcohol exposure on the developing fetus," Dr. Astley added. "The vast majority of infants born with the most severe outcome of prenatal alcohol exposure (FAS and partial FAS) were not small for gestational age, were not born premature, and were not the result of a pregnancy complicated by preeclampsia, despite heavy exposure to alcohol in utero."

Dr. Sarah Lewis of the University of Bristol in the UK, who has also studied the effects of fetal exposure to alcohol, echoed the cautious notes from Dr. Astley.

"The study shows no convincing evidence of a harmful effect of alcohol on the outcomes examined, but there are serious methodological problems in this and other observational studies which means that harmful effects may have been missed," she told Reuters Health by email.

"There is some evidence from quasi experimental designs (which are more powerful), which suggest that alcohol exposure early in life may have an effect on cognition, educational achievement and employment prospects as well as the risk of early spontaneous abortion," Dr. Lewis said.

"It is very difficult, almost impossible, to isolate the effect of alcohol on pregnancy outcomes in these studies, because the women who drink (particularly in moderation) tend to be more well educated, older mothers who eat healthy and tend not to smoke," she added. "These factors are generally beneficial for the child and may mask any detrimental effect of alcohol. In addition, women may not be honest when answering questionnaires, and many women in the abstention group may actually be heavy drinkers, or were heavy drinkers prior to and in the early stages of pregnancy. Finally many women declined to take part in the survey and we cannot rule out an effect of drinking in those women."

Dr. McCarthy did not respond to a request for comments by press time.

SOURCE: http://bit.ly/17YU3Wk

Obstet Gynecol 2013;122:830-837.