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11: Fetal lung maturity and neonatal outcome >34 weeks: do antenatal steroids improve outcomes if administered after negative maturity results?

      Objective

      Following immature fetal lung indices, obstetricians may choose one of three clinical management strategies: (1) treat with antenatal corticosteroids (ACS) with subsequent planned delivery, (2) await repeat testing with mature indices, or (3) expectant management. We tested the hypothesis that the approach of ACS administration after fetal lung immaturity would not improve neonatal outcome in infants >34 weeks.

      Study Design

      This retrospective cohort study compared outcomes of 365 infants born >34 weeks after fetal lung maturity testing: 102 had immature fetal lung indices and were treated with ACS followed by planned delivery within one week, 78 had immature fetal lung indices and were managed expectantly, and 185 delivered after mature amniocentesis. We analyzed differences between groups in a composite adverse neonatal outcome (NICU admission, ongoing respiratory support, phototherapy, antibiotic treatment, intravenous fluids for hypoglycemia, or gavage feeding) and a composite respiratory outcome (oxygen supplementation, continuous positive airway pressure, mechanical ventilation, or surfactant administration) by univariable and multivariable analyses.

      Results

      Infants born after immature fetal lung indices followed by ACS therapy and delivery had significantly higher rates of neonatal morbidity, including oxygen supplementation, CPAP, hypoglycemia, and antibiotic treatment, compared to the other two groups (p<0.05). After adjusting for statistically influential and biologically plausible variables, infants managed expectantly were 90% less likely to have adverse respiratory outcome (aOR 0.1, 95% CI 0.01-0.9). Infants born after mature amniocentesis were 50% less likely to have adverse neonatal outcome (aOR 0.5, 95% CI 0.3-0.9) and 60% less likely to have adverse respiratory outcome (aOR 0.3, 95% CI 0.1-0.9).

      Conclusion

      Administration of ACS following immature fetal lung indices did not decrease rates of neonatal respiratory morbidity in infants born >34 weeks. As more mature infants had less neonatal morbidity, our study supports prolonging gestation until delivery is otherwise indicated.
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