UK researchers found that drinking a small amount of alcohol in pregnancy, as in no more than 1 to 2 units a week, does not harm children in that they were at no greater risk of developing behavioural difficulties than children of mothers who abstained while pregnant.

Lead author Dr Yvonne Kelly of the Epidemiology & Public Health department of University College London (UCL) conducted the study with colleagues from UCL and other research establishments in the UK. Their findings were published on 30th October in the Advance Access issue of the International Journal of Epidemiology.

Kelly said that:

“The link between heavy drinking during pregnancy and consequent poor behavioural and cognitive outcomes in children is well established.”

“However, very few studies have considered whether light drinking in pregnancy is a risk for behavioural and cognitive problems in children,” she added.

For the study the researchers used data from the UK Millennium Cohort Study, which covered 12,495 three year-old children, interviewed their mothers about their drinking patterns during pregnancy and assessed behavioural and cognitive outcomes of the children themselves. The drinking measure used was what the researchers told the mothers: a unit was about half a pint of beer (about 300 ml), a glass of wine, or a single measure of spirit or liqueur.

The researchers found that:

  • Children born to mothers who drank a little alcohol (1 to 2 units a week) while pregnant were not more likely to have behavioural difficulties or cognitive deficits compared to children born to mothers who abstained during pregnancy.

  • Indeed, for some behavioural and cognitive outcomes, children born to light drinkers were less likely to have problems compared to children of mothers who abstained.

  • But children born to mothers who drank heavily while pregnant were more likely to have behavioural and cognitive problems compared to children of mothers who abstained in pregnancy.

  • Even after adjusting for family and socioeconomic factors, boys born to mothers who drank lightly were 40 per cent less likely to have “conduct” problems and 30 per cent less likely to show hyperactive behaviour.

  • Compared to boys born to mothers who abstained, boys whose mothers drank only a little alcohol while pregnant were also more likely to score higher in vocabulary tests and exercises where they had to identify colours, shapes, letters and numbers.

  • Girls born to mothers who only drank a little alcohol were 30 per cent less likely to have emotional and peer problems compared to girls born to mothers who abstained, but this tendency appeared to depend partly on family and social background.

Kelly and colleagues concluded that:

“Children born to mothers who drank up to 1-2 drinks per week or per occasion during pregnancy were not at increased risk of clinically relevant behavioural difficulties or cognitive deficits compared with children of abstinent mothers.”

“Heavy drinking during pregnancy appears to be associated with behavioural problems and cognitive deficits in offspring at age 3 years whereas light drinking does not,” they added.

Speculating on the reasons behind the findings, Kelly suggested that it might partly be because:

“Light drinkers tend to be more socially advantaged than abstainers, rather than being due to the physical benefits of low level alcohol consumption seen, for example, in heart disease.”

“However, it may also be that light-drinking mothers tend to be more relaxed themselves and this contributes to better behavioural and cognitive outcomes in their children,” she added.

The current policy in the UK about drinking during pregnancy is confusing and inconsistent, although there appears to be a push toward total abstinence in order to be on the safe side. However, Kelly questions this:

“There is inconsistency in policy around this issue and studies such as this one are vital in light of the wider debate around drinking and pregnancy,” she said.

“Our study’s findings do raise questions as to whether the current push for policy to recommend complete abstinence during pregnancy is merited and suggest that further research needs to be done,” added Kelly.

” Light drinking in pregnancy, a risk for behavioural problems and cognitive deficits at 3 years of age?”
Yvonne Kelly , Amanda Sacker , Ron Gray , John Kelly , Dieter Wolke , and Maria A Quigley.
International Journal of Epidemiology, Advance Access published on October 30, 2008.
DOI 10.1093/ije/dyn230

Click here for Article (PDF download).

Sources: UCL.

Written by: Catharine Paddock, PhD.