Alcohol and congenital heart defects: an experimental study in mice.

Pregnant mice were exposed to a single dose of alcohol (0.03 ml of 25% alcohol X g-1 mouse) or two doses (2 X 0.015 ml of 25% alcohol X g-1 mouse) 4 h apart, by intraperitoneal injection or by gavage, on days 7, 8, 9 or 10 of gestation. The mice were killed on the day before term and the fetuses examined for heart defects. Alcohol exposure on day 8, 9 or 10 of gestation caused a high incidence of ventricular septal defects (60%, 75% and 15% respectively). Defects of both the membranous and muscular parts of the septum were seen as well as more complex ventricular septal defects involving the great vessels. Day 7 was resistant to the induction of heart defects. This study has demonstrated that a relatively short exposure to high doses of alcohol during pregnancy in mice can cause congenital heart defects. This has important implications both as a possible cause of congenital heart anomalies in humans and for the counselling of mothers of affected children.