Light drinking in pregnancy may not cause developmental issues during mid-childhood, according to a new British study published in an International Journal of Obstetrics and Gynaecology (BJOG). Light drinking was defined as up to 2 units of alcohol — 50ml of spirits, 175ml of wine or a little less than a pint of beer — per week.

Study details

Researchers from the University College London analysed data from 10,534 seven-year-olds who participated in the Millennium Cohort Study, a national study involving infants born in the UK between 2000 and 2002.

Nine months after delivery, the mothers were asked to recall their alcohol consumption during pregnancy — 57.1 percent claimed they were teetotallers and 23.1 percent said they were light drinkers.

When the children turned seven, their parents and teachers filled in questionnaires investigating the kids’ social and emotional behaviour — including hyperactivity, attention and conduct issues — as well as cognitive performance in maths, reading and spatial skills.

Study findings

The authors stressed that they found no significant difference in terms of behavioural problems between infants born to mothers who abstained from alcohol and those who were light drinkers. However, boys born to light drinkers had slightly fewer reported behavioural problems.

After adjusting for potential confounders, only boys born to light drinkers were found to perform a little better in reading and spatial skills tests.

Why take the risk?

Although this research was well-designed, Patrick O’Brien, consultant obstetrician and spokesman for the Royal College of Obstetricians and Gynaecologists (RCOG), told the BBC that “[the study] didn’t control for all [confounding factors] like IQ”.

Alcohol adversely affects babies’ IQ

In November 2012, researchers from Oxford and Bristol Universities showed that a single unit of alcohol per week during pregnancy could influence foetal brain development, resulting in decreased IQ levels. The scientists used genetic testing, a very accurate technology that automatically eliminates potential confounders.

Alcohol linked to Foetal Alcohol Spectrum disorders (FASD)

According to US scientists, unborn babies are at increased risks of FASD — a cluster of birth abnormalities and disabilities — for every unit of alcohol consumed by the mother, especially during the first trimester.

Study implications

“We need to understand more about how children’s environments influence their behavioural and intellectual development. While we have followed these children for the first seven years of their lives, further research is needed to detect whether any adverse effects of low levels of alcohol consumption in pregnancy emerge later in childhood,” co-author Yvonne Kelly, co-director of the ESRC International Centre for Lifecourse Studies (ICLS) at University College London said.

Official guidelines

The UK Department of Health advises pregnant women and those trying to conceive to avoid alcohol altogether. However, if expecting women want to drink, they should consume no more than 1 to 2 units of alcohol once or twice a week.

Better err on the side of caution

“It remains unclear as to what level of alcohol consumption may have adverse outcomes,” declared John Thorp, BJOG’s deputy editor-in-chief in a press release.

It is worth remembering that the way the body’s enzymes process alcohol is influenced by genes. This means that the vulnerable foetus would be exposed to alcohol for a longer period of time if the mother’s enzymes are not that efficient.


    Kelly et al (2013) Light drinking versus abstinence in pregnancy - behavioural and cognitive outcomes in 7-year-old children: a longitudinal cohort study. BJOG. 10.1111/1471-0528.12246.