The brain is thought to be particularly sensitive to the neurotoxic effects of ethanol during the “brain growth spurt period,” which occurs during the last trimester of gestation in humans.

Prenatal exposure to ethanol has been associated previously with fetal alcohol effects (FAE) and/or fetal alcohol syndrome (FAS), potential contributors to retarded growth, neurological and behavioral deficits, and mental retardation.

In a study designed to evaluate the effects of ethanol on the infant’s brain, a 20% solution of ethanol in normal saline was administered to seven-day-old rats in two separate treatments given two hours apart. Each treatment delivered 2.5 g/kg, while a control group was treated with saline only. Brains were examined 24 hours after the first treatment to assess the cellular status and possible degeneration/loss of brain cells.

Results: Exposure of the developing rat brain to ethanol for a period of hours during a specific developmental stage induced a “neurogenerative reaction” that deleted large numbers of neurons from several major regions of the developing brain. The authors point out that this developmental stage (the first two weeks after birth in rats) coincides with development from the sixth month of pregnancy until birth in humans. In their conclusion, they warn that “if a pregnant mother imbibes ethanolic beverages for several hours in a single drinking episode, she could expose her third-trimester fetus to blood ethanol levels equivalent to those required to trigger apoptotic neurodegeneration in the immature rat brain.”