Trends in survival, perinatal morbidities and two-year neurodevelopmental outcomes in extremely low-birthweight infants over four decades

Abstract

Background: Although outcomes for infants born extremely low birthweight (ELBW; <1000 g birthweight) have improved over time, it is important to document survival and morbidity changes following the advent of modern neonatal intensive care in the 1990s.

Objective: To describe trends in survival, perinatal outcomes and neurodevelopment to 2 years' corrected age over time across six discrete geographic cohorts born ELBW between 1979 and 2017.

Methods: Analysis of data from discrete population-based prospective cohort studies of all live births free of lethal anomalies with birthweight 500-999 g in the state of Victoria, Australia, over 6 eras: 1979-80, 1985-87, 1991-92, 1997, 2005 and 2016-17. Perinatal data collected included survival, duration and type of respiratory support, neonatal morbidities and two-year neurodevelopmental outcomes.

Results: More ELBW live births were inborn (born in a maternity hospital with a neonatal intensive care unit) over time (1979-80, 70%; 2016-17, 84%), and more were offered active care (1979-80, 58%; 2016-17, 90%). Survival to 2 years rose substantially, from 25% in 1979-80 to 80% in 2016-17. In survivors, rates of any assisted ventilation rose from 75% in 1979-80 to 99% in 2016-17. Cystic periventricular leukomalacia, severe retinopathy of prematurity and blindness improved across eras. Two-year data were available for 95% (1054/1109) of survivors. Rates of cerebral palsy, deafness and major neurodevelopmental disability changed little over time. The annual numbers with major neurodevelopmental disability increased from 12.5 in 1979-80 to 30 in 2016-17, but annual numbers free of major disability increased much more, from 31 in 1979-80 to 147 in 2016-17.

Conclusions: Active care and survival rates in ELBW children have increased dramatically since 1979 without large changes in neonatal morbidities. The numbers of survivors free of major neurodevelopmental disability have increased more over time than those with major disability.

Keywords: extremely low birthweight; follow-up studies; infant; intensive care; neonates; neurodevelopmental disability.