Time Trends in Neonatal Mortality Among Twins and Singletons in New York City, 1968–1986

Abstract

AbstractThe objective of this study was to compute yearly neonatal mortality rates (NMRs) in twins and compare these to rates in singletons during the same time period. The focus was on time trends in birthweight-specific twin mortality in the birth population of New York City during the years 1968 to 1986. The study population was all twin livebirths ≥ 500 g birthweight (N = 45,605), with a comparison group of all singleton livebirths in the same birthweight range (N = 2,191,144). Data came from the New York City Department of Health's computerized vital records on livebirths and infant deaths. Between 1968 and 1986 the crude NMR declined 39% in twins and 47% in singletons. In twins there were birthweight-specific declines of 69% to 84% between 1000 g and 2499 g. However, there was only a 19% decline in the twin NMR over 2499 g. This contrasts with a 50% decline in the singleton NMR over 2499 g. In New York City, modern medical care has been remarkably successful in lowering the NMR in low birthweight twins. However, more effort must be made to understand the etiology of perinatal problems in twins with birth weights greater than 2500 g.