This report presents data from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network on care of and morbidity and mortality rates for very low birth weight infants, according to gestational age (GA).
Perinatal/neonatal data were collected for 9575 infants of extremely low GA (22–28 weeks) and very low birth weight (401–1500 g) who were born at network centers between January 1, 2003, and December 31, 2007.
Rates of survival to discharge increased with increasing GA (6% at 22 weeks and 92% at 28 weeks); 1060 infants died at ≤12 hours, with most early deaths occurring at 22 and 23 weeks (85% and 43%, respectively). Rates of prenatal steroid use (13% and 53%, respectively), cesarean section (7% and 24%, respectively), and delivery room intubation (19% and 68%, respectively) increased markedly between 22 and 23 weeks. Infants at the lowest GAs were at greatest risk for morbidities. Overall, 93% had respiratory distress syndrome, 46% patent ductus arteriosus, 16% severe intraventricular hemorrhage, 11% necrotizing enterocolitis, and 36% late-onset sepsis. The new severity-based definition of bronchopulmonary dysplasia classified more infants as having bronchopulmonary dysplasia than did the traditional definition of supplemental oxygen use at 36 weeks (68%, compared with 42%). More than one-half of infants with extremely low GAs had undetermined retinopathy status at the time of discharge. Center differences in management and outcomes were identified.
Although the majority of infants with GAs of ≥24 weeks survive, high rates of morbidity among survivors continue to be observed.
Comments
Outcomes at the border of viability with optimal care
Dear Editor,
We read with great interest the neonatal outcome data of extremely preterm infants from the NICHD neonatal research network as it helps in the decisions to provide active obstetric care and to initiate neonatal intensive care at the border of viability (22-24 weeks(1). The EXPRESS group published outcome data on a population cohort of extremely preterm infants (< 27 weeks) after active perinatal care and demonstrated survival rates higher than the NICHD study. ( 52% vs 26% at 23 weeks and 67% vs 55% at 24 weeks)(2) Although the authors acknowledge that they did not collect sufficient data on center differences in obstetric/early neonatal interventions, the data in the current study has to be interpreted with caution. The rate of multiple births in the NICHD study is 30% at 23 weeks compared to 16% in the Swedish study. The outcome of multiple gestations is poor compared to singleton pregnancy at all gestational ages (3). Also the use of antenatal steroids was higher in the Swedish study compared to the NICHD study (85% versus 53% at 23 weeks). The percentage of babies undergoing resuscitation at 23 weeks was also higher in the Swedish study compared to the NICHD study (81% versus 65%). All these factors might have contributed to the lower survival rates at 23 weeks in the NICHD data and since the survival depends greatly on these factors, it would be useful to know the survival data after accounting for these confounding factors. (That is survival rate for a singleton pregnancy with prenatal steroids and optimal resuscitation)
In describing the survival without morbidities, the NICHD data included infections as a morbidity where as it was not included the Swedish study. The incidence of late onset sepsis was 62% at 23 weeks gestation. Should all the infections be really counted towards significant morbidity as opposed to the ones that cause a sepsis syndrome? Also it would be good to have data on survival without significant neurosensory morbidity (grade 3 or more IVH, PVL or severe ROP) as these are the morbidities that carry on into a child’s life. It is hard to discern such outcome measures from the data presented in the paper.
References: 1) Stoll BJ, Hansen NI, Bell EF,et al. Neonatal outcomes of extremely preterm infants from the NICHD neonatal research network. Pediatrics. 2010; 126(3):443-56 2) EXPRESS Group, Fellman V, Hellstrom-Westas L , et al. One-year survival of extremely preterm infants after active perinatal care in Sweden. JAMA. 2009; 301(21):2225-33 3) Refuerzo JS, Momirova V, Peaceman AM, et al. Neonatal outcomes in twin pregnancies delivered moderately preterm, late preterm, and term. Am J Perinatol. 2010; 27(7):537-42
Conflict of Interest:
None declared