Heavy drinking during pregnancy has been associated with fetal alcohol syndromea pattern of characteristic physical features, birth defects, poor growth and developmental delay.
However, the effects of alcohol during pregnancy are not yet well understood. Does an occasional drink raise risk? Does alcohol contribute to birth defects in babies who do not have the full-blown fetal alcohol syndrome? What is the effect of binge drinking?
To answer these questions, the California Birth Defects Monitoring Program routinely asks about alcohol consumption in interview studies with mothers of babies with a variety of birth defects. Here are some findings.
CLEFT LIP AND CLEFT PALATE
Women who drink alcohol regularly do not have a higher risk of having babies with oral clefts compared to non-drinkers.
However, "binge" drinking5 or more drinks per occasionon a weekly or more frequent basis increases cleft lip and palate risk 3 to 7 times.
Other factors known to affect cleft risksuch as smoking and vitamin usedid not account for these findings.
None of the studied babies born to heavy drinkers had features of fetal alcohol syndrome such as low birth weight or small heads.
Down syndrome. Women with high alcohol consumption (more than 4 drinks/week) were less likely to have recognized Down syndrome pregnancies. Pregnancies with Down syndrome are known to be prone to miscarriage; alcohol may increase this susceptibility, thereby reducing the chance of having a recognized Down syndrome pregnancy.
Gastroschisis. Using alcohol (either daily or binge drinking) increases risk by 2 to 4 times for this life-threatening birth defect where the intestines protrude through a hole in the abdominal wall.