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109: The effect of exposure to antenatal corticosteroids on the rate of respiratory morbidity among late preterm infants

      Objective

      To evaluate whether exposure to antenatal corticosteroids affects the rate of respiratory morbidity among late preterm infants.

      Study Design

      This was a retrospective cohort study of late preterm infants (defined as 34 0/7 and 36 6/7 weeks) delivered between January 2005 and December 2006. Records were reviewed to determine the gestational age at delivery, mode of delivery, plurality, gender, maternal diabetes, antenatal steroid exposure (ACS), and newborn respiratory outcome. Neonatal respiratory morbidity was defined as respiratory distress syndrome (RDS), transient tachypnea (TTN), or use of therapeutic CPAP or mechanical ventilation. Cases with major fetal malformations were excluded.

      Results

      In a cohort of 722 infants, 136 (18.8%) had received a complete course of ACS prior to delivery (mean: 30.0 days; range: 1-82 days). Of neonates exposed to ACS prior to delivery, 36 (5%) had received ACS within 14 days of delivery. There was a higher frequency of respiratory morbidity among neonates exposed to ACS within 14 days of delivery (6/36; 16.7%) than among those never exposed (87/586; 14.8%). After controlling for other factors associated with respiratory morbidity, however, there was a trend towards decreased respiratory morbidity among neonates exposed to ACS within 14 days of delivery (OR 0.385; p 0.057). Only gestational age and mode of delivery were associated with a statistically significant impact on respiratory morbidity.

      Conclusion

      Although exposure to ACS within 14 days of delivery is associated with a trend toward decreased risk of respiratory morbidity, respiratory outcomes among late preterm infants appear to be influenced by gestational age at delivery and mode of delivery.
      Tabled 1Influence of ACS exposure and obstetric factors on respiratory morbidity of late preterm infants:
      Adj OR95% CIp
      ACS < 14 days0.3850.144, 1.0300.057
      GA0.3280.245, 0.440<0.005
      Cesarean delivery1.8171.066, 3.0960.028
      Male gender1.3831.066, 1.3830.182
      Maternal diabetes0.9220.443, 1.9220.829
      Twin0.8650.517, 1.4500.583