WHEN IS THE OPTIMAL TIME FOR DELIVERY - PURELY FROM THE FETUSES PERSPECTIVE

To determine when the extrauterine environment becomes safer than the intrauterine environment with respect to fetal (neonatal) life, we ana lyzed all 4,896,505 livebirths, all 21,222 stillbirths, and all 7,513 early neonatal deaths after 26 weeks of gestation that were recorded b etween 1989 and 1992 in Japan. Although the risks of early neonatal de ath (<1 week of age) and of neonatal death (<4 weeks of age) greatly e xceeded the risk of stillbirth at 26 weeks of gestation, those risks d eclined sharply by 39 weeks of gestation, then increased, while the ri sk of stillbirth within 1 and 4 weeks remained constantly low until 38 and 40 weeks of gestation, respectively, and increased thereafter. Th e risk of stillbirth within 1 and 4 weeks exceeded the risks of early neonatal death and of neonatal death at and beyond gestational weeks 4 0 and 38, respectively, for a singleton pregnancy. A similar reversal occurred at 37 and 35 weeks of gestation for a multiple pregnancy. Neo nates born at 39 and 37 weeks of gestation for singleton and multiple pregnancies, respectively, had the best outcomes. It is concluded that the chance of survival for fetuses reaching 40 and 37 weeks of gestat ion for singleton and multiple pregnancies, respectively, were higher in the extrauterine than the intrauterine environment in Japan today.