Drinking alcohol during and even beyond the first trimester of pregnancy doesn't seem to raise the risk of premature delivery, low birth weight or size, or high blood pressure complications for the mother, a new study claims.
The study, however, drew sharp criticism from the chief medical officer of the March of Dimes, which recommends against drinking alcohol during pregnancy.
The new study was led by Dr Fergus McCarthy of the Irish Centre for Fetal and Neonatal Translational Research (INFANT), at Cork University Maternity Hospital in Ireland. McCarthy and his colleagues presented their findings in the October issue of the journal Obstetrics & Gynecology.
The study authors focused on more than 5 600 pregnant women who enrolled in the study between 2004 and 2011 in Australia, Great Britain, Ireland and New Zealand. All the women were interviewed between the 14th and 16th week of pregnancy about their alcohol consumption both before becoming pregnant and during the first 15 weeks of gestation.
The majority of the women 6 in 10 said they'd consumed some alcohol during the first four months of pregnancy. These women were more likely to be younger, white and single, with a history of smoking or drug use.
Nearly 1 in 5 said they'd drank occasionally, meaning one to two "units" of alcohol per week. One unit was defined as equal to a glass of wine or a little less than a 12-ounce bottle of beer.
One quarter said they had engaged in low alcohol consumption, meaning three to seven units a week, while just over 10% said they had engaged in moderate consumption 8 to 14 units a week. 5% reported drinking heavily more than 14 units a week.
At the extreme end, more than one-third of the women said they had consumed 6 or more units of alcohol in one session in the three months before becoming pregnant a practice defined as binge drinking. And nearly a quarter of those women said they'd binged during the first 15 weeks of their pregnancy.
After comparing the mothers' drinking histories with the status of their babies at birth, the study authors concluded that drinking both pre-pregnancy and during the first 15 weeks of pregnancy did not seem to increase the risk that a baby would be born prematurely, low in birth weight or small for gestational age regardless of the amount of alcohol consumed.
Nor was drinking linked to a potentially life-threatening complication known as "preeclampsia", in which a pregnant woman develops high blood pressure.
The study authors, however, cautioned against any broad interpretation of the findings, noting that their focus was solely on drinking during early pregnancy, and on specific measures of a baby's health at the moment of birth. The study did not measure alcohol's potential impact on a baby's development for the long term.
For his part, Dr Edward McCabe, chief medical officer of the March of Dimes, stressed that his organisation continues to adhere to its long-standing position that drinking alcohol during pregnancy can cause permanent harm to the child, and no amount of maternal drinking is safe.
"The March of Dimes feels that if you're pregnant or even thinking about getting pregnant you should not drink alcohol," he said. "That means no wine, wine coolers, beer or liquor."
"And critically," McCabe added, "I should point out that after a long build-up where the authors [of the new study] are sort of talking up the myth regarding recommendations that pregnant women not drink, at the end of their article they say, and I quote: 'It remains unclear whether any safe level of alcohol consumption in pregnancy exists.' Which means that the final take-home message of this paper is actually not to drink while pregnant."
"So actually... the authors agree with the March of Dimes' position," McCabe said. "They are not saying that it's safe to drink alcohol during pregnancy."
Read more about the March of Dimes' position on drinking during pregnancy.