Antenatal Betamethasone and Incidence of Neonatal Respiratory Distress After Elective Caesarean Section: Pragmatic Randomized Trial

Abstract

Corticosteroids given antenatally have reduced the incidence of respiratory distress in preterm infants. The randomized ASTECS trial was done to learn whether steroids have this effect when given to term infants delivered electively by cesarean section. A total of 998 women at 10 maternity units were randomized to receive either 2 intramuscular 12-mg doses of betamethasone within 48 hours before delivery or no steroid treatment. The treatment and control groups were similar in maternal age, asthma, and smoking history, as well as infant gender and birth weight. Of 35 newborn infants admitted to special units because of respiratory distress, 24 had not received steroid (P = 0.02). The relative risk of an infant in the treatment group being admitted to a special unit with respiratory distress was 0.46 (95% confidence interval [CI], 0.23-0.93). The risk ratio for transient tachypnea of the newborn was 0.54 (95% CI, 0.26-1.12). The risk ratio for respiratory distress syndrome in treatment cases was 0.21 (95% CI, 0.03-1.32). Respiratory distress was equally severe for treatment and control infants admitted to special care units. Logistic regression analysis showed that the predicted likelihood of admission to special care with respiratory distress at 37 weeks gestation was 5.2% in the treatment group and 11.4% in the control group. The respective figures at 38 weeks were 2.8% and 6.2%, and at 39 weeks, 0.6% and 1.5%. Adverse effects, most often generalized flushing, were noted in 7 mothers given steroid treatment. Antenatal treatment with betamethasone reduces the need for admitting newborn infants to special care units with respiratory distress after term cesarean delivery. Delaying delivery to 39 weeks gestation also is helpful.