The perinatal mortality rate is widely used as a summary statistic for evaluating the effectiveness of perinatal care. Since October, 1992, it has been a legal requirement in England and Wales to register fetal deaths at 24-27 completed weeks of gestation as stillbirths (in addition to those after 28 weeks), thereby altering the definition of perinatal death. In a cohort analysis of all babies born to women resident in Wales during 1993, we assessed whether the revised definition of perinatal mortality rate more appropriately measures effectiveness of care. There were 36,793 births and 313 perinatal deaths (221 stillbirths, 92 early neonatal deaths). At 24-27 weeks' gestation there were 59 (39%) survivors and 93 deaths (52 stillbirths, 36 neonatal deaths [28 early, eight late], and 5 postneonatal deaths). 119 babies had a birthweight below 500 g; one survived and 24 were perinatal deaths. Of the 36 late neonatal deaths all were attributed to perinatally related events. Increased survival of infants at 24-27 weeks' gestation emphasises the importance of including all these infants in the perinatal mortality rate, but it would be a more useful measure of the effectiveness of perinatal care if it excluded babies below 500 g, and included late neonatal deaths.
PIP: The perinatal mortality rate is widely used as a summary statistic for evaluating the effectiveness of perinatal care. A major drawback with using the perinatal mortality rate in such fashion, however, has been the inclusion of all registered live births, irrespective of gestational age, while stillbirths were registered only after 28 completed weeks; fetal deaths before that gestational age were not registered and thus not included in the perinatal mortality rate. Moreover, at very low gestational ages, the expectation of viability may influence the judgement of whether a fetus is stillborn or is born alive but dies shortly after birth. The World Health Organization has recommended that national perinatal statistics include only fetuses and infants of at least 500g at birth, alive or dead. It has been law in England and Wales since October 1992 to register fetal deaths at 24-27 completed weeks of gestation as stillbirths. This legislation has therefore changed the definition of perinatal death in the UK. In a cohort analysis of all babies born to women resident in Wales during 1993, the authors assessed whether the revised definition of perinatal mortality rate more appropriately measures the effectiveness of care. There were 36,793 births, 221 stillbirths, and 92 early neonatal deaths. At 24-27 weeks' gestation there were 59 survivors, 52 stillbirths, 36 neonatal deaths, and 5 postneonatal deaths. 119 babies had a birthweight below 500g, one who survived and 24 who died perinatally. All 36 late neonatal deaths were attributed to perinatally related events. The increased survival of infants at 24-27 weeks' gestation emphasizes the importance of including all these infants in the perinatal mortality rate, but it would be a more useful measure of the effectiveness of perinatal care if the definition excluded babies below 500g and included late neonatal deaths.