Low Apgar score and mortality in extremely preterm neonates born in the United States.

Abstract

To investigate the relationship between low Apgar score and neonatal mortality in preterm neonates. Infant birth and death certificate data from the US National Center for Health Statistics for 2001-2002 were analysed. Primary outcome was 28-day mortality for 690, 933 neonates at gestational ages 24-36 weeks. Mortality rates were calculated for each combination of gestational age and 5-min Apgar score. Relative risks of mortality, by high vs. low Apgar score, were calculated for each age. Distribution of Apgar scores depended on gestational age, the youngest gestational ages having higher proportions of low Apgar scores. Median Apgar score ranged from 6 at 24 weeks, to 9 at 30-36 weeks gestation. The relative risk of death was significantly higher at Apgar scores 0-3 vs. 7-10, including at the youngest gestational ages, ranging from 3.1 (95% confidence interval 2.9, 3.4) at 24 weeks to 18.5 (95% confidence interval 15.7, 21.8) at 28 weeks. Low Apgar score was associated with increased mortality in premature neonates, including those at 24-28 weeks gestational age, and may be a useful tool for clinicians in assessing prognosis and for researchers as a risk prediction variable.