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Birth weight less than 800 grams: changing outcomes and influences of gender and gestation number
1Child Development and Mental Retardation Center, University of Washington, Seattle.
Insights
Despite improved survival rates for very low birth weight neonates, neurodevelopmental morbidity has worsened. This includes increased severity of central nervous system handicaps, particularly in twins.
Area of Science:
- Neonatal Intensive Care
- Perinatal Medicine
- Developmental Pediatrics
Background:
- Two cohorts of neonates with birth weights < 800g were compared.
- Neonates were from the same university intensive care nursery.
- Cohorts represented 1977-1980 (original) and 1983-1985 (current).
Purpose of the Study:
- To compare mortality and neurodevelopmental morbidity between two historical cohorts of extremely low birth weight neonates.
- To identify factors influencing survival and handicap severity in this population.
Main Methods:
- Retrospective cohort study comparing mortality and neurodevelopmental outcomes.
- Analysis of survival rates based on birth weight, gender, and gestation (singleton vs. twin).
- Assessment of central nervous system (CNS) handicap prevalence and severity.
Main Results:
- Overall mortality decreased from 80% to 64% (P=.01).
- Higher birth weight (>749g) and being female or singleton were associated with improved survival in the current cohort.
- While prevalence of major CNS handicaps did not differ, severity worsened, with twins experiencing the most severe morbidity (67%).
Conclusions:
- Improved survival for extremely low birth weight neonates has not translated to better neurodevelopmental outcomes.
- Increased severity of CNS handicaps, especially in twins, is a significant concern.
- Delivery mode may impact outcomes, warranting further investigation.
Abstract:
Mortality and neurodevelopmental morbidity were compared in two cohorts of neonates with birth weights of less than 800 g. The neonates, born in the years 1977 through 1980 (original cohort) and 1983 through 1985 (current cohort), were patients in the same university intensive care nursery. Mortality was 80% in the original cohort and 64% in the current cohort (P = .01). In the current cohort, survival was significantly better for neonates with birth weights of more than 749 g (58% vs 27%; P = .001). Survival was also significantly associated with gender and with gestation number (female survival was 48% and male survival was 23%, P = .003; singleton survival was 41% and twin survival was 21%, P = .03). Prevalence of major central nervous system handicaps did not significantly differ between the two study groups, but severity of handicap was worse for the current study group. Morbidity in the current cohort was most severe for twins (67% with a major central nervous system handicap) and was least severe for singleton girls (4% with a major central nervous system handicap, P = .002). Delivery mode appeared to affect outcome. Although there were more nursery admissions and more survivors among neonates with birth weights of less than 800 g during the period 1983 through 1985 compared with the period 1977 through 1980, overall neurodevelopmental morbidity worsened.