We have evaluated the effects of varying degrees and durations of hypothermia, combined with anesthesia, on pregnant rats of the Sherin Wistar Strain. Moderate (surgical) and intermediate hypothermia, with ether anesthesia, were safe for both fetus and mother. With pentobarbital anesthesia, however, there were harmful effects, depending on the depth and duration of hypothermia; moderate hypothermia increased fetal and maternal mortality. The combination of CO₂ narcosis and deep hypothermia induced no ill effects
