Even moderate drinking in pregnancy may affect child's IQ

It has been known for a while that substantial alcoholic drinking increases the risk of birth defects or may negatively affect the child in other ways, but now studies show that even moderate drinking can play a role in the intelligence of a child.  There are four genetic variations that control the enzymatic ability to metabolize ethanol, some of which metabolize faster than others.  These differences in metabolism indicate about how long the alcohol levels will be high for (so basically, the slower the metabolizing, the more likely one is to be considered a "lightweight").  After analyzing the genes of over 4,000 mothers during the course of their pregnancies, it was found that children of the mothers who consumed between one and six drinks a week had lower IQ scores by the time they were eight years old.

All four of the genetic variations were present in the study of the children, and these alcohol-metabolizing genes were related to the IQ's identified.  For each variation the children had, their IQ scores were two points lower.  This data was compared against children whose mothers did not consume any alcohol during pregnancy, and there was no significant effect on the IQ's.  The observations made lead to conclude that alcohol consumed (whether moderate or substantial) during pregnancy has an effect on the future IQ of the fetus.

As ridiculous as it may sound, I never actually realized that genetic variations played a role in how ones body metabolizes alcohol/ethanol.  Also, although I did always believe alcohol during pregnancy would always have an effect on the future child, I am somewhat surprised that all it takes for there to be an effect is one glass a week.  Because something like this can so easily risk harm to or lower the IQ of a fetus, it makes me wonder if there are any other chemicals/nutrients that could affect a fetus so quickly and without much effort, but in the opposite way.  So is there something similar to ethanol that could be consumed once a week throughout pregnancy that would enhance a fetus' IQ?