Abstract and Introduction
Abstract
Background: Preterm birth is increasing worldwide, and late preterm births, which comprise more than 70% of all preterm births, account for much of the increase. Early and late onset sepsis results in significant mortality in extremely preterm infants, but little is known about sepsis outcomes in late preterm infants.
Methods: This is an observational cohort study of infants <121 days of age (119,130 infants less than or equal to 3 days of life and 106,142 infants between 4 and 120 days of life) with estimated gestational age at birth between 34 and 36 weeks, admitted to 248 neonatal intensive care units in the United States between 1996 and 2007.
Results: During the study period, the cumulative incidence of early and late onset sepsis was 4.42 and 6.30 episodes per 1000 admissions, respectively. Gram-positive organisms caused the majority of early and late onset sepsis episodes. Infants with early onset sepsis caused by Gram-negative rods and infants with late onset sepsis were more likely to die than their peers with sterile blood cultures (odds ratio [OR]: 4.39, 95% CI: 1.71–11.23, P = 0.002; and OR: 3.37, 95% CI: 2.35–4.84, P < 0.001, respectively).
Conclusion: Late preterm infants demonstrate specific infection rates, pathogen distribution, and mortality associated with early and late onset sepsis. The results of this study are generalizable to late preterm infants admitted to the special care nursery or neonatal intensive care unit.
Introduction
The incidence of preterm births (<37 weeks gestation) is increasing in many countries around the world and has become a global health concern. More than 70% of preterm infants are born between 34 and 36 weeks gestation (late preterm). Most large series describing the epidemiology of neonatal sepsis are limited to infants with very low gestational age (<33 weeks) or very low birth weights (<1500 g birth weight).
Late preterm infants are traditionally perceived by clinicians as physiologically similar to full-term infants and are often treated similarly. Recent evidence suggests, however, that late preterm infants (relative to full-term infants) are diagnosed with culture-proven sepsis more frequently, have increased sepsis-related mortality, and have a substantial increased risk for morbidity and mortality. Studies describing the epidemiology of early onset sepsis (EOS) and late onset sepsis (LOS) in late preterm infants are lacking, therefore, the United States National Institute of Child Health and Human Development of the National Institutes of Health issued an agenda to increase knowledge and understanding of complications related to late preterm birth. Towards this end, we aimed to evaluate risk factors, pathogen distribution, cumulative incidence, and mortality of EOS and LOS in a large cohort of late preterm infants admitted to 248 neonatal intensive care units (NICU) in the United States.