A new study used genetic data to provide clear evidence that drinking even small amounts of alcohol during pregnancy can adversely affect the development of babies and their IQ levels.
Previous studies have been inconsistent, but this one from researchers at the Universities of Bristol and Oxford found that four genetic variants in alcohol-metabolising genes in children and their mothers were strongly related to lower IQ levels at the age of eight.
Researchers used data from 4,167 mothers and children, discovering that on average the child's IQ was almost two points lower per genetic modification amongst the children of women who drank between one and six drinks a week during pregnancy. The children of women who abstained during pregnancy did not show this genetic modification.
Researchers used the genetic data to separate the impact of alcohol from other lifestyle factors such as smoking and diet.
Dr Ron Gray, from Oxford University, who led the research added that although the differences appeared small, they may well be significant and that lower IQ had been shown to be associated with being socially disadvantaged, having poorer health and even dying younger.
"It is for individual women to decide whether or not to drink during pregnancy, we just want to provide the evidence.
"But I would recommend avoiding alcohol. Why take the risk?"
The RCM welcomed the research. Janet Fyle, their professional policy advisor, said: "This adds weight to the RCM's advice that women should avoid alcohol when they are pregnant or planning a pregnancy.
"We have been consistent in our view that cumulative alcohol consumption has damaging effects on the fetus. The researchers rightly point out that there is often ambiguity in the advice given to women about alcohol. The RCM's acknowledges that some women may have consumed alcohol before realising that they are pregnant. If they are worried, they should speak to their midwife for advice."
But Dr Clare Tower, consultant in obstetrics and fetal maternal medicine, at St Mary's Hospital, Manchester, stressed that women who have had the occasional alcoholic drink in pregnancy should not be overly alarmed by the findings. She said that although she would advise women that abstinence is the safest option, another recent study had found no effect on IQ at five years.
"It is likely therefore," she explained, "that any impact is small and not seen in all women."
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