Effects of prenatal alcohol exposure on birth weight in rats: is there an inverted U-shaped function?

Decreases in birth weight are among the most commonly reported effects of prenatal alcohol exposure in animals. However, these decreases are typically associated with relatively high doses of alcohol. Two studies were conducted. The first evaluated the effects of low doses of alcohol (0.15 and 0.30 g/kg) on birth weight and other measures. A second study examined the effects of a relatively high dose of alcohol (3.0 g/kg). The two low doses of alcohol produced a slight, but not significant, increase in birth weight relative to vehicle controls whereas the high dose of alcohol produced a significant decrease in birth weight relative to its controls. When the data for the two studies were combined, the relationship between alcohol and birth weight assumed an inverted U-shaped function. There was no effect of prenatal alcohol exposure on weights at weaning, passive avoidance learning, or ambulation. In the context of birth weight, slight increases may be related to increased protein synthesis associated with low doses of alcohol.