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Perinatal factors influencing survival in extremely low-birthweight infants
A Finan1, M Ledwidge, T Clarke
1Department of Paediatrics, Rotunda Hospital, Dublin, Ireland.
Insights
Survival for extremely low birth weight infants (<1000g) is significantly influenced by gestational age and birthweight. A higher 5-minute Apgar score also improves survival chances for these vulnerable newborns.
Area of Science:
- Neonatalogy
- Perinatal Medicine
- Pediatric Critical Care
Background:
- Extremely low birth weight (ELBW) infants (<1000g) account for most deaths in normally formed newborns.
- While survival rates for ELBW infants have improved, significant center-to-center variations persist, necessitating accurate local outcome data for parental counseling and quality assurance.
- Accurate outcome data is crucial for parental counseling and maintaining high standards of care in neonatal intensive care units.
Purpose of the Study:
- To analyze factors influencing survival in normally formed extremely low birth weight infants (500-999g).
- To identify key determinants of survival to 28 days in this high-risk neonatal population.
- To provide local outcome figures for improved parental counseling and care standards.
Main Methods:
- Retrospective analysis of 126 normally formed infants between 500g and 999g birthweight, born between January 1990 and December 1995.
- Statistical analysis to identify factors affecting survival to 28 days, controlling for gestational age.
- Evaluation of variables including birthweight, gestation, Apgar scores, mode of delivery, and maternal factors.
Main Results:
- Overall survival rate for ELBW infants in this cohort was 63%.
- Gestational age and birthweight were the most significant predictors of survival, with survival increasing from 33% at 24 weeks to 100% at 28 weeks, and from 29% at 500-599g to 87% at 900-999g.
- A 5-minute Apgar score greater than 5 significantly increased the odds of survival (OR 3.97). Mode of delivery and chorioamnionitis influenced survival variably by gestational age.
Conclusions:
- Gestational age and birthweight are paramount factors for ELBW infant survival.
- While many factors were not significant predictors of survival after controlling for gestational age, a higher 5-minute Apgar score positively impacts outcomes.
- Mode of delivery and chorioamnionitis require further investigation for their impact on survival, potentially influenced by gestational age.
Abstract:
The majority of deaths in normally formed infants occur in extremely low birth weight infants (< 1000 g). Survival rates for these infants have improved greatly but still vary from centre to centre and accurate local outcome figures are important for counselling parents and upholding standards of care. In the Rotunda Hospital, Dublin, over the 6 year period from 1 January 1990 to 31 December 1995, there were 34 474 deliveries over 500 g birthweight. One hundred and twenty-six of these were normally formed infants between 500 g and 999 g. Our objective was to analyse the factors influencing survival in these extremely low birthweight (ELBW) infants. Overall survival in the group was 63%. The most significant factors influencing survival to 28 days were gestation and birthweight. Survival increased from 33% at 24 weeks to 100% at 28 weeks' gestation and from 29% at 500-599 g to 87% at 900-999 g birthweight. Having controlled for gestational age, none of the following variables had a significant effect on survival: year of birth; gender; multiple pregnancy; 1-minute Apgar score; maternal age; parity; use of antenatal steroids; a history of antepartum haemorrhage, pre-eclamptic toxaemia or prolonged rupture of membranes. A 5-min Apgar score > 5 increased the chance of survival by 3.97 (95% CI: 1.46- 10). Both mode of delivery and incidence of chorioamnionitis had an influence on survival which varied according to the gestational age. A larger cohort of survivors would illustrate the effect of these variables more clearly.
