Neonatal Outcomes at Extreme Prematurity by Gestational Age Versus Birth Weight in a Contemporary Cohort

Abstract

Objective The aim of the study is to describe the rates of neonatal death and severe neonatal morbidity in a contemporary cohort, as well as to evaluate the predictive value of birth gestational age (GA) and birth weight, independently and combined, for neonatal mortality and morbidity in the same contemporary cohort. Study Design We performed a secondary analysis of an international, multicenter randomized controlled trial of delayed umbilical cord clamping versus umbilical cord milking in preterm infants born at 230/7 to 316/7 weeks of gestation. The current analysis was restricted to infants delivered <28 weeks. The primary outcomes of this analysis were neonatal death and a composite of severe neonatal morbidity. Incidence of outcomes was compared by weeks of GA, with planned subanalysis comparing small for gestational age (SGA) versus non-SGA neonates. Multivariable logistic regression was then used to model these outcomes based on birth GA, birth weight, or a combination of both as primary independent predictors to determine which had superior ability to predict outcomes. Results Of 474 neonates in the original trial, 180 (38%) were included in this analysis. Overall, death occurred in 27 (15%) and severe morbidity in 139 (77%) neonates. Rates of mortality and morbidity declined with increasing GA (mortality 54% at 23 vs. 9% at 27 weeks). SGA infants (n = 25) had significantly higher mortality compared with non-SGA infants across all GAs (p < 0.01). There was no difference in the predictive value for neonatal death or severe morbidity between the three prediction options (GA, birth weight, or GA and birth weight). Conclusion Death and severe neonatal morbidity declined with advancing GA, with higher rates of death in SGA infants. Birth GA and birth weight were both good predictors of outcomes; however, combining the two was not more predictive, even in SGA infants. Key Points