Even moderate drinking in pregnancy can affect a child's IQ
Relatively small levels of exposure to alcohol while in the womb can influence a child's IQ, according to a new study led by researchers from the universities of Bristol and Oxford using data from over 4,000 mothers and their children in the Children of the 90s study (ALSPAC) and published in PLOS ONE.
Current advice to pregnant women about moderate alcohol consumption during pregnancy is contradictory, with some official guidelines recommending complete abstinence and others suggesting that moderate use is safe. Previous studies have produced conflicting and inconsistent evidence on the effects of moderate alcohol intake on a child's IQ. This may be because it is difficult to separate the effects of moderate alcohol consumption from other lifestyle and social factors, such as smoking, diet, affluence, mother's age and education.
This study, believed to be the first substantial one of its kind, used genetic variation to investigate the effects of moderate (less than 1 to 6 units of alcohol per week) drinking during pregnancy among a large group of women and their children. Since the individual variations that people have in their DNA are not connected to lifestyle and social factors, the approach removes that potential complication.
Four genetic variants in alcohol-metabolising genes among the 4,167 children were strongly related to lower IQ at age eight. The child's IQ was on average almost two points lower per genetic modification they possessed.
But this effect was only seen among the children of women who were moderate drinkers. There was no effect evident among children whose mothers abstained during pregnancy, strongly suggesting that it was the exposure to alcohol in the womb that was leading to the difference in child IQ. Heavy drinkers were not included in the study.
Speaking about the findings, the report's main author, Dr Sarah Lewis, said: 'Our results suggest that even at levels of alcohol consumption which are normally considered to be harmless, we can detect differences in childhood IQ, which are dependent on the ability of the foetus to clear this alcohol. This is evidence that even at these moderate levels, alcohol is influencing foetal brain development.'
Dr Ron Gray from the NPEU, University of Oxford who led the research added: 'This is a complex study but the message is simple: even moderate amounts of alcohol during pregnancy can have an effect on future child intelligence. So women have good reason to choose to avoid alcohol when pregnant.'