Population-based trends in mortality and neonatal morbidities among singleton, very preterm, very low birth weight infants over 16 years

Background: Improved survival of singleton very preterm, very low birth weight (VPTVLBW) infants has been associated with increasing rates of severe neonatal morbidities.

Aim: To assess changes in mortality and neonatal morbidities among singleton VPT-VLBW infants.

Study design: Population-based observational study of data collected by the Israel Neonatal Network.

Subjects: 10,705 singleton VPT-VLBW infants born at 24-32 gestational weeks in 1995-2010.

Outcome measures: Mortality and major neonatal morbidities over 3 time periods: 1995-2000, 2001-2005, and 2006-2010. Major neurological morbidities comprised intraventricular hemorrhage grades 3-4, periventricular leukomalacia and retinopathy of prematurity grades 3-4.

Results: The mortality rate decreased over time from 20.2% to 13.8% for all birth weight and gestational age groups. Compared to the 1995-2000 period, the adjusted odds ratios (aORs) (95% confidence intervals,) for mortality in 2001-2005 and 2006-2010 were 0.78 (0.67-0.90) and 0.72 (0.62-0.84), respectively. The combined outcomes of death or major neurological morbidities, aOR 0.74 (0.65-0.84) and death or major neurological morbidities and/or bronchopulmonary dysplasia aOR 0.85 (0.75-0.96) decreased significantly between the first and last periods. A significant improvement in mortality rates and survival without one or more major neonatal morbidity was observed for all birth weight and gestational age groups. Among 8,886 surviving infants the rates of major neurological morbidities decreased from 16.4% to 12.8%, aOR 0.80 (0.68-0.95).

Conclusion: The improving survival of singleton VTP-VLBW infants was not associated with a concomitant increase in the risk for major neonatal neurological morbidities among surviving infants. Bronchopulmonary dysplasia, however, remained a significant burden. This analysis emphasizes the need to direct efforts towards the prevention and treatment of adverse respiratory sequelae.