Prenatal stress alters maternal aggression in mice.

Prenatal stress (heat and restraint) reduced pregnancy-induced and elevated postpartum aggression in Rockland-Swiss (R-S) albino female mice. Though prenatally-stressed females were indistinguishable from control animals with respect to parental behavior during the virgin state, the former displayed slightly lower levels of nestbuilding during early pregnancy, and delivered slightly more male offspring at parturition. The young born to prenatally-stressed females exhibited deficits in birth weights and body weight gain in contrast to pups delivered by control females. The anogenital distances of prenatally-stressed females were shorter than those of control females, suggesting that alterations in fetal testosterone exposure may be responsible for disruptions in behavior and reproduction.