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Is there a lower limit for birth-weight/gestational age and antenatal steroid therapy?
L W Doyle1, M J Permezel, W H Kitchen
1Department of Obstetrics and Gynaecology, University of Melbourne, Parkville, Victoria, Australia.
Insights
Antenatal steroid therapy significantly improves survival rates for premature infants, even those with very low birth weights or early gestational ages. This treatment can double survival chances for the smallest infants, offering hope for improved outcomes.
Area of Science:
- Perinatology
- Neonatology
- Obstetrics
Background:
- Premature infants face significant mortality risks.
- Antenatal steroid therapy is a known intervention to improve outcomes for preterm neonates.
- The efficacy in extremely preterm infants requires further investigation.
Purpose of the Study:
- To determine if a lower limit of birth weight or gestational age exists below which antenatal steroid therapy is ineffective.
- To assess the association between antenatal steroid therapy and survival in extremely low birth weight and gestational age infants.
Main Methods:
- Retrospective cohort study analyzing two groups of infants (birth weight <800g or gestational age <27 weeks).
- Assessed survival rates to 2 years of age.
- Adjusted for extraneous prognostic variables.
Main Results:
- Antenatal steroid therapy was linked to higher survival in infants weighing 500-599g and 700-799g, and at 25-26 weeks gestational age.
- Survival was limited before 25 weeks and nonexistent below 500g birth weight.
- Antenatal steroids approximately doubled survival rates for infants aged 24-26 weeks and weighing 500-799g.
Conclusions:
- Antenatal steroid therapy appears to benefit survival in extremely preterm infants without a discernible lower limit of birth weight or gestational age.
- Obstetricians can potentially improve survival chances for the smallest and most immature infants by administering antenatal steroids.
- The study supports the use of antenatal steroids in mothers at risk of preterm delivery, provided no maternal contraindications exist.
Abstract:
The aim of this study was to determine if there is a lower limit for birth-weight/gestational age below which antenatal steroid therapy may not improve fetal survival. The association between antenatal steroid therapy and survival to 2 years of age was assessed in 2 cohorts of children of birth-weight below 800 g or of gestational ages below 27 weeks. Antenatal steroid therapy was associated with significantly higher survival rates in infants of birth-weight 500-599 g and 700-799 g, and at gestational ages of 25 and 26 weeks. There were few survivors before 25 weeks and none below 500 g birth-weight. After adjustment for extraneous prognostic variables, antenatal steroid therapy was associated overall with approximately a doubling of the survival rates of infants of birth-weight 500-799 g, and of gestational ages 24-26 weeks. In the absence of maternal contraindications, if the goal is to deliver a surviving infant, this study suggests that the obstetrician may assist the survival chances of the tiniest and most immature infants by treating the mother with steroids before birth, with no apparent lower limit of birth-weight or gestational age.