Improved survival and neurodevelopmental outcomes among extremely premature infants born near the limit of viability
Introduction
Infants born near the limit of viability are at high risk for death or adverse neurodevelopmental outcomes [1], [2], [3], [4], [5]. Recent evidence suggests that survival has improved in this population over the past 20 years [5], [6], but there is little evidence that neurodevelopmental outcomes of surviving infants have changed. Two multicenter studies by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Neonatal Research Network reported that neurodevelopmental outcomes did not improve the over consecutive birth epochs in infants born 22–24 weeks' gestation between 1993 and 2004 [1], [4]. The most recent of these studies reported death in 67.6% of these infants in 2002–2004, and neurodevelopmental impairment (NDI) in 58.7% of survivors [4]. A recent study from Japan's Neonatal Research Network described better than previously reported outcomes in this group, with death or NDI seen in 80.0% of infants born at 22 weeks' gestation, 63.7% at 23 weeks' gestation, and 38.9% at 24 weeks' gestation [7]. Current knowledge of outcomes for infants born at these early gestational ages is critical for clinicians and families when making early obstetrical and neonatal care decisions [8].
The objective of this study was to compare death and early childhood neurodevelopmental outcomes for infants born < 25 weeks' gestation in our center between two recent birth epochs.
Section snippets
Study population
We identified all infants born 22 0/7–24 6/7 weeks' gestation that were admitted to the Neonatal Intensive Care Unit at Duke University Medical Center from January 1, 1998 to December 31, 2011. Infants admitted from an outside hospital at > 48 h of age were excluded. The study period was divided into two epochs. Epoch 1 included infants born from 1998 to 2004 and Epoch 2 included infants born from 2005 to 2011. Epoch 1 was chosen to overlap with the most recent NICHD Neonatal Research Network
Results
During the study period, a total of 357 infants were born at 22–24 weeks of gestation. Of these infants, 170 (48%) were born in Epoch 1 and 187 (52%) were born in Epoch 2. Epoch 1 and 2 infants did not differ significantly in birth weight, GA, inborn status, gender, multiple gestations, or receipt of antenatal steroids (Table 1). The proportion of infants born by cesarean delivery was higher in Epoch 2. Among surviving infants, incidence of severe IVH, periventricular leukomalacia,
Discussion
In our center, survival of infants born 22–24 weeks of GA has improved over the past 15 years. In fact, we observed decreased mortality as well as decreased NDI among survivors. When the cohort was divided by birth GA, we saw a decrease in NDI in infants born at 24 weeks of gestation, but no improvement in the outcomes among the infants born at 23 weeks of gestation. While these results are limited by the small number of surviving infants born at 23 weeks of gestation in our cohort, it suggests that
Conclusions
In our center, the incidence of death or NDI decreased over time in infants born 22–24 weeks of gestation. In particular, NDI significantly decreased in infants born at 24 weeks of gestation. While these results are encouraging, the rates of death or NDI remain very high and clinicians should continue to counsel parents of the significant risks at these early gestational ages. Further research is needed to identify and implement practices associated with improving the outcomes in this vulnerable
Conflicts of interest
The authors have no relevant conflicts of interest to disclose.
Acknowledgments
Dr. Younge received support from National Institutes of Health (5T32HD043728-10). Dr. Smith received support from the National Institutes of Health and the National Center for Advancing Translational Sciences (HHSN267200700051C, HHSN275201000003I and UL1TR001117); he also receives research support from industry for neonatal and pediatric drug development (www.dcri.duke.edu/research/coi.jsp). Dr. Cotten received support from National Institutes of Health (5U10 HD040492-10).
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