The Contribution of Preterm Birth to Infant Mortality Rates in the United States

TLDR

Although two thirds of infant deaths in the United States occur among infants born preterm (<37 weeks of gestation), only 17% of infant deaths are classified as being attributable to preterm birth with the standard classification of leading causes of death. The study aimed to more accurately estimate preterm birth’s contribution to infant mortality by identifying the top 20 leading causes of infant death in 2002 using linked birth/infant death data. The authors assessed preterm birth’s role for each cause by determining the proportion of infants born preterm for each cause and considering biological connections, using 27,970 linked records where the 20 leading causes accounted for 22,273 deaths (80% of all infant deaths). They found that 9,596 infant deaths (34.3% of all infant deaths) were attributable to preterm birth, with 95% occurring in infants <32 weeks and <1500 g, two thirds within the first 24 hours, making preterm birth the most frequent cause of infant death in 2002 and underscoring the need for comprehensive prevention strategies.

Abstract

Although two thirds of infant deaths in the United States occur among infants born preterm (<37 weeks of gestation), only 17% of infant deaths are classified as being attributable to preterm birth with the standard classification of leading causes of death. To address this apparent discrepancy, we sought to estimate more accurately the contribution of preterm birth to infant mortality rates in the United States.We identified the top 20 leading causes of infant death in 2002 in the US linked birth/infant death file. The role of preterm birth for each cause was assessed by determining the proportion of infants who were born preterm for each cause of death and by considering the biological connection between preterm birth and the specific cause of death.Of 27970 records in the linked birth/infant death file for 2002, the 20 leading causes accounted for 22273 deaths (80% of all infant deaths). Among infant deaths attributable to the 20 leading causes, we classified 9596 infant deaths (34.3% of all infant deaths) as attributable to preterm birth. Ninety-five percent of those deaths occurred among infants who were born at <32 weeks of gestation and weighed <1500 g, and two thirds of those deaths occurred during the first 24 hours of life.On the basis of this evaluation, preterm birth is the most frequent cause of infant death in the United States, accounting for at least one third of infant deaths in 2002. The extreme prematurity of most of the infants and their short survival indicate that reducing infant mortality rates requires a comprehensive agenda to identify, to test, and to implement effective strategies for the prevention of preterm birth.