Behavioral, biochemical and histological effects of prenatal administration of progesterone in the rat.

Pregnant Wistar rats were injected with progesterone (1.5 mg/kg) between Days 8 and 21 of gestation and the behavioral, biochemical and histological effects of this treatment were observed in the offspring. The progesterone offspring weighed less than the control animals during this weaning and were retarded on one measure of exploratory activity in the open field. None of the other 29 tests used showed any significant difference apart from a 9% increase in the amount of brain DNA in the progesterone animals. It was concluded that these differences were fortuitous and that progesterone has no consistent or significant effects on brain development in rodents following prenatal administration.