FETAL AND PLACENTAL RESPONSES TO ARTIFICIALLY INDUCED HYPERTHERMIA IN RATS

Pregnant rats were utilized to study the effect of maternal hyperthermia on fetal development. Groups (8) of 6-8 rats were exposed to ambient temperatures of 43-44.degree. C at various stages of pregnancy. All rats were killed on day 20 of gestation. Edema, microencephaly and microphthalmia followed heat treatment on day 4, 6 or 8 and skeletal defects occurred on day 10 of gestation. Apparently heat stress of dams after day 14 of gestation had little or no effect on embryos. Most placentas from day 6-10 treatment groups were significantly heavier than control and exhibited extensive thickening and necrosis of decidua basalis. The rat apparently is a useful model for investigating maternal hyperthermia as a possible cause of human placentopathies and fetal retardation.