all factors linked to higher IQ in children and which could mask any negative effects of alcohol. A U.S. study published in July found that older, educated women are more likely to drink while pregnant. GENES AFFECT ALCOHOL METABOLISM This study, published in the journal PLOS ONE on Wednesday, used a new technique analyzing the genetic variants which modify the effects of alcohol exposure levels. When a person drinks alcohol, ethanol is converted to acetaldehyde by a group of enzymes, the researchers explained. Variations in genes that 'encode' these enzymes lead to differences in a person's ability to metabolize ethanol, so in "slow metabolizes", alcohol levels may be higher for longer than in "fast metabolizes". Scientists think fast ethanol metabolism protects against abnormal brain development because less alcohol goes to the fetus. The mothers were asked to record their alcohol consumption at various stages during pregnancy, and one drink was specified as one unit of alcohol. The results showed that four genetic variants in alcohol-metabolizing 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 variation they had. The effect was only seen among children of women who were moderate drinkers and there was no effect evident in children of mothers who abstained during pregnancy. This strongly suggests it was exposure to alcohol in the womb that led to the difference in child IQ, the researchers said. "This is a complex study but the