Teratogenic interaction of hyperthermia and vitamin A.

Exposure of pregnant hamsters to 60--75 min of hyperthermia on the 8th day of gestation causes malformations in some of the fetuses recovered near term. The feeding of large doses of vitamin A to pregnant hamsters on the 8th day of gestation causes many of the same types of malformations. When pregnant hamsters are treated with the minimal teratogenic hyperthermic stress plus the minimal teratogenic dose of vitamin A there is a clear augmentation of the teratogenic effect on the embryo. The implication that maternal hyperthermia may be an important synergistic factor for a variety of potentially teratogenic influences during pregnancy is discussed.