That flash before your eyes? That was the pendulum swinging—specifically, the drink-or-don't-drink-during-pregnancy pendulum. A new study has found even light drinking during pregnancy results in a lower IQ for a certain subset of babies, which has led the authors of the study to conclude drinking and pregnancy don't mix. Like it's 1998 all over again!
But before you go into a mom guilt-induced coma there's a catch: only some developing fetuses will be adversely affected by their mother's occasional glass of wine. It all depends on mom's and child's abilities to metabolize alcohol.
The study, published in the journal PLoS ONE and reported on recently in the Los Angeles Times, looked at more than 4,000 women who had been recruited during pregnancy and their children at around 8 years old. None of the women in the study drank heavily during pregnancy, but some drank moderately (between one and six drinks a week). Others in the study didn't drink at all. Not only were the fetus-turned-8-year-olds tested for their IQs, but their DNA was tested for certain genetic variants. It was deep in the ADH gene, which produces an enzyme that breaks down alcohol, where researchers could finally see why—and for whom—even small amounts of alcohol could have a negative effect on kids.
Children who carried one or more of four genetic variations in the ADH gene showed a lower IQ on average—around two points lower per gene variation—if their mothers also reported drinking during pregnancy. And that's even if they reported drinking very little. Children who had any or all of the variations, but whose moms did not drink, showed no drop in IQ, as did kids whose moms drank moderately but who could metabolize alcohol normally.
The study sheds some light on why studies on drinking during pregnancy seem so confusing: the rarely common inability to breakdown alcohol is why it can be harmful, but why it's not universally so.
Most of us turned out OK and most present-day fetuses will turn out OK even if exposed to alcohol in the womb.
So how do you know?
You don't, though certain populations have been said to have a higher rate of an inability to metabolize alcohol—Native Americans and East Asians, for example.
In the last couple of years, strict advice to totally abstain from drinking while pregnant gave way to the reassurance Come on, lighten up! A glass won't hurt! All of that looked through the lens of modern parents' own fetalhood, which involved moms pounding Mai Tais and Virginia Slims and, well, we turned out OK. Right?
Sort of right. Most of us turned out OK and most present-day fetuses will turn out OK even if exposed to a little alcohol in the womb. But the exceptions are what make these researchers conclude that since you don't know whether your child will be the exception, it's best to play it safe and wait until your baby is swaddled in your arms before pouring yourself a cold one.