Understanding the relative contributions of prematurity and congenital anomalies to neonatal mortality

Objective To examine the relative contributions of preterm delivery and congenital anomalies to neonatal mortality. Study design Retrospective analysis of 2009–2011 linked birth cohort-hospital discharge files for California, Missouri, Pennsylvania and South Carolina. Deaths were classified by gestational age and three definitions of congenital anomaly: any ICD-9 code for an anomaly, any anomaly with a significant mortality risk, and anomalies recorded on the death certificate. Result In total, 59% of the deaths had an ICD-9 code for an anomaly, only 43% had a potentially fatal anomaly, and only 34% had a death certificate anomaly. Preterm infants (<37 weeks GA) accounted for 80% of deaths; those preterm infants without a potentially fatal anomaly diagnosis comprised 53% of all neonatal deaths. The share of preterm deaths with a potentially fatal anomaly decreases with GA. Conclusion Congenital anomalies are responsible for about 40% of neonatal deaths while preterm without anomalies are responsible for over 50%.