Prenatal stress reduces maternal aggression by mice offspring

Pregnant mice were subjected to the simultaneous stress of heat, restraint and bright lights during the last trimester of gestation whereas control mothers remained unhandled in the home cage. As adults, prenatally-stressed and nonstressed mice were mated and tested for maternal aggression. Compared with nonstressed controls, prenatally-stressed females bit intruder males on significantly fewer occasions. Prenatal stress therefore reduced maternal aggression by mice offspring. Prenatal stress also significantly reduced maternal and neonatal body weight. Because the appearance of maternal aggression characteristically has been associated with the postpartum period, prenatal stress may reduce maternal aggression in mice by disrupting gonadotropin secretions (possibly prolactin) associated with the lactational phase.