Moderate drinking during pregnancy can affect child's IQ
Children who are exposed to alcohol while in the womb may have lower IQ, a new study led by researchers from the universities of Bristol and Oxford has suggested.
The study that used data from over 4,000 mothers and their children in the Children of the 90s study (ALSPAC) found that even moderate amounts of alcohol consumption during pregnancy can have an effect on future child's intelligence.
This study, believed to be the first substantial one of its kind, used genetic variation to investigate the effects of moderate (less than1-6 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.
When a person drinks alcohol, ethanol is converted to acetaldehyde by a group of enzymes. Variations in the genes that 'encode' these enzymes lead to differences in their ability to metabolise ethanol. In 'slow metabolisers', peak alcohol levels may be higher and persist for longer than in 'fast metabolisers'.
It is believed that the 'fast' metabolism of ethanol protects against abnormal brain development in infants because less alcohol is delivered to the fetus, although the exact mechanisms are still unclear.
"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," the report's main author, Dr Sarah Lewis, said.
Dr Ron Gray from the 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."
The study has been published in PLOS ONE.