Neonatal Outcomes of Moderately Preterm Infants Compared to Extremely Preterm Infants

BACKGROUND: Extremely preterm infants (EPT, <29 weeks’ gestation) represent only 0.9% of births in the U.S., yet these infants are focus of most published research. Moderately preterm neonates (MPT, 29–33(6/7) weeks), are an understudied group of high-risk infants. METHODS: Objective: To determine the neonatal outcomes of MPT across the gestational age spectrum, and to compare these to EPT. A prospective observational cohort was formed in 18 Level 3–4 NICUs in the Eunice Kennedy Shriver NICHD Neonatal Research Network. Participants included all MPT admitted to NICUs, and all EPT born at sites between January 2012 and November 2013. Antenatal characteristics, and neonatal morbidities were abstracted from records using pre-specified definitions by trained neonatal research nurses. RESULTS: MPT infants experienced morbidities similar to, although at lower rates, than EPT infants. The main cause of mortality was congenital malformation, accounting for 43% of deaths. CNS injury occurred including intraventricular hemorrhage. Most MPT required respiratory support but sequelae such as bronchopulmonary dysplasia were rare. The primary contributors to hospitalization beyond 36 weeks’ gestation were inability to achieve adequate oral intake and persistent apnea. CONCLUSIONS: MPT experience morbidity and prolonged hospitalization. Such morbidity deserves focused research to improve therapeutic and prevention strategies.