Prenatal stimulation and postnatal testosterone affects infanticide in female rats

Prenatal handling, prenatal stress, and early postnatal exogeneous testosterone were examined in female rats for their effects on rat pup-killing and pup retrieval. During each of the last 5 days of pregnancy, Long-Evans rats received either 3 minutes of handling, 45 minutes of restraint and intense illumination or remained untouched. Half of the offspring of each group received testosterone from Day 1 after birth to Day 30. In adulthood, animals that received handling prenatally and testosterone postnatally killed pups more rapidly than any other group and a larger proportion did so than in the control groups. Animals not manipulated at any time retrieved pups more rapidly and a larger proportion did so than the combined other groups. The study suggests that prenatal handling interacts with testosterone presented immediately postnatally to increase infanticide in female rats. A variety of perinatal manipulations seem to suppress pup retrieval.