Just two alcoholic drinks a week in early pregnancy may increase the risk of having a premature or small baby, and it is middle-class women who are most likely to drink more than this.
Women who drank more than two weekly alcohol units were twice as likely to give birth to an unexpectedly small or premature baby than women who abstained completely, a study has found.
Pregnant women who drank more than two weekly units during the first three months were more likely to be older, educated to degree level, of white ethnicity, and more likely to live in well-off areas.
The findings, published in the Journal of Epidemiology and Community Health and based on responses to food questionnaires by 1,264 pregnant women in Britain, reinforces the abstinence- only message.
All of the women at low- risk of birth complications were part of the Caffeine and Reproductive Health study which examined links between diet and birth outcomes.
Alcohol consumption was significantly higher before conception and during the first three months of pregnancy than during the subsequent two trimesters, averaging 11, four, and just under two units a week respectively.
More than half (53%) of the women drank more than the recommended maximum two units a week during the first three months.
Almost four out of 10 said they drank more than 10 units a week shortly before becoming pregnant.
The study found that 13% of the babies were underweight when born; 4.4% were smaller than would be expected and 4.3% were born prematurely.
Drinking during the first three months of pregnancy was most strongly linked to the outcomes. Even pregnant women who did not exceed the maximum recommended alcohol intake in the first three months were still at an increased risk of a premature birth.
Drinking in the lead up to conception was also linked to higher risk of restricted foetal growth.
“Our results highlight the need for endorsing the abstinence-only message and further illuminate how timing of exposure is important in the association of alcohol with birth outcomes, with the first trimester being the most vulnerable period,” the study authors wrote.
The Department of Health and Children recommends that women refrain from drinking alcohol during their pregnancy.
The department says alcohol offers no benefits to pregnancy outcomes, and it is in the child’s best interest that it is avoided.
Meanwhile, another study has found that girls born small or underweight are twice as likely to be infertile in adulthood.
The findings of the study, published in the online only British Medical Journal Open, are based on 1,206 women who were born in Sweden from 1973 onwards. Just under 4% of the women had been born prematurely; a similar proportion were underweight at birth, while just under 6% were unexpectedly small babies.
Women with fertility problems were almost three times as likely to have been born unexpectedly small as those whose main cause of infertility was unexplained.
However, as it is the first research of its kind, they say further studies will be needed before definitive conclusions can be drawn.
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