London: Women who drink as little as half a pint of beer per week during pregnancy can cut their baby`s intelligence level by several IQ points, a new study claims.
Researchers suggest this could be enough to make a difference to the child`s prospects, in the study that teased out a true relationship between moderate drinking in pregnancy and its affect on an unborn child.
While the damaging impact of heavy drinking on foetal development is well-known, studies of moderate drinking have given contradictory results, `New Scientist` reported.
Researchers led by Ron Gray at the University of Oxford studied the effects of genetic mutations in alcohol dehydrogenase genes. These mutations slow the breakdown of alcohol.
Humans carry several dehydrogenase genes and differ in the number of mutations that they contain, from none to 10.
The more of these mutations a foetus has, the more slowly it will break down alcohol that its mother drinks.
So, if alcohol reduces the IQ, it should be lowered in children with more mutations, and that in turn should be independent of social variables.
However, the mutations should have no effect if a mother hasn`t drunk any alcohol, the report said.
The study found that children with four or more of the mutations averaged 3.5 points lower on a standard IQ test than children with 2 or fewer, but only if their mothers drank 1 to 6 units per week during the pregnancy.
And no such difference was seen in children of non-drinkers, regardless of their genes.
The mothers` genotype had almost no impact on the IQ results, suggesting that the effect has little to do with how fast the mother breaks down alcohol, and everything to do with how the foetus handles it.