Drinking alcohol during pregnancy leads to poorer cognitive functioning in children, according to scientists.

They reviewed 23 published studies on drinking during pregnancy and found evidence it could also lead to lower birthweight.

The findings reinforce the UK Chief Medical Officers’ #DRYMESTER guidelines, which is abstaining from alcohol in all trimesters.

To study the effects of drinking alcohol during pregnancy, the researchers combined results from very different study designs for the first time.

Methods included traditional studies such as randomised controlled trials, alongside alternative strategies such as comparing children in the same families whose mothers cut down or increased their alcohol use between pregnancies, and a genetic marker-based approach, “Mendelian randomisation”.

Previously, research on this topic has been through “observational” studies, where participants are already exposed to a risk factor and researchers do not try to change who is or is not exposed.

All the studies included in the review tried to compare like-with-like groups of people, who were only different in terms of exposure to alcohol during pregnancy.

While the review was comprehensive, it was limited in its ability to establish how much alcohol leads to these negative outcomes.

The researchers concluded that women should continue to be advised to abstain from alcohol during pregnancy.

Study lead Dr Luisa Zuccolo, from the University of Bristol, said: “The body of evidence for the harm that alcohol can do to children before they are born is growing, and our review is the first to look at the full range of studies on the issue.

“This is unlikely to be a fluke result, as we took into account a variety of approaches and results.

“Our work confirms the current scientific consensus: that consuming alcohol during pregnancy can affect one’s child’s cognitive abilities later in life, including their education. It might also lead to lower birthweight.

“Our study reinforces the UK Chief Medical Officers’ guideline: DRYMESTER is the only safe approach.

“This message is more important than ever, given recent research which shows the alcohol industry promoting confusing information about the real health implications of drinking during pregnancy.”

The research was funded by the National Institute for Health Research and the Medical Research Council.

Deputy chief medical officer Professor Jenny Harries said: “If you are pregnant or you are planning to become pregnant, national guidelines recommend the safest approach is to not drink at all, to keep the risk to your baby to a minimum.

“We have been clear with the alcohol industry that we expect these guidelines to be reflected on the labelling of all alcoholic products.

“Public Health England, the NHS and local authorities continue to reinforce this advice through public health messaging.”

– The paper, Evidence of detrimental effects of prenatal alcohol exposure on offspring birthweight and neurodevelopment from a systematic review of quasi experimental studies, is published in the International Journal of Epidemiology.