Abstract
OBJECTIVE: To evaluate if the Apgar score remains pertinent in contemporary practice after more than 50 years of wide use, and to assess the value of the Apgar score in predicting infant survival, expanding from the neonatal to the post-neonatal period. METHODS: The U.S. linked live birth and infant death dataset was used, which included 25,168,052 singleton births and 768,305 twin births. The outcome of interest was infant death within 1 year after birth. Cox proportional hazard-model was used to estimate risk ratio of infant mortality with different Apgar scores. RESULTS: Among births with a very low Apgar score at five minutes (1-3), the neonatal and post-neonatal mortality rates remained high until term (≥ 37 weeks). On the other hand, among births with a high Apgar score (≥7), neonatal and post-neonatal mortality rate decreased progressively with gestational age. Non-Hispanic White had a consistently higher neonatal mortality than non-Hispanic Black in both preterm and term births. However, for post-neonatal mortality, Black had significantly higher rate than White. The pattern of changes in neonatal and post-neonatal mortality by Apgar score in twin births is essentially the same as that in singleton births. CONCLUSIONS: The Apgar score system has continuing value for predicting neonatal and post-neonatal adverse outcomes in term as well as preterm infants, and is applicable to twins and in various race/ethnic groups.