The aim of the present study was to compare the survival, physical development and spontaneous behavior of rat pups born from white rats subjected to acute hypobaric hypoxia on the 3rd-5th days of gestation (progestation) period or on the 9-10th day of gestation (period of early organogenesis). It was shown that the delayed effects of progestation hypoxia were less expressed than those following acute hypoxia modeled in the early organogenesis. In latter case, hypoxia led to the increased mortality among rat pups of both sexes while hypoxia-induced delay in physical development and changes in spontaneous behavior and anxiety level were registered up to the 57th day of postnatal period.