Effectiveness of a rescue dose of antenatal betamethasone after an initial single course

To evaluate the effects of a single rescue dose of antenatal betamethasone after an initial single course on the frequency of neonatal respiratory distress syndrome and perinatal infectious morbidity in pregnancies complicated with preterm labor and delivery.

We performed a cohort analysis of singleton pregnancies for which delivery occurred between 28 and 34 weeks' gestation after a single course of betamethasone administered before 28 weeks' gestation. Patients were then segregated into the following 2 groups on the basis of betamethasone exposure at the delivery admission: (1) a single 12-mg injection (rescue group) and (2) observation only (observation group). Patients who delivered infants within 24 hours of the rescue dose were excluded, as were those who had ruptured membranes for longer than 24 hours before delivery, those with diabetes that required insulin, and those with exposure to repeated doses of betamethasone before admission. Data were analyzed by use of the Student t test, chi2 test, and Fisher exact test. Multiple logistic regression was performed to examine the effect of each steroid dosing regimen on respiratory distress syndrome. Two-tailed P values <.05 were considered to be significant.

A total of 152 patients were included, with 89 in the rescue group and 63 in the observation group. Both groups were similar with respect to maternal demographics, mean gestational age at the initial single course and at delivery, mode of delivery, and mean birth weights. Rescue administration was significantly associated with a reduction in the frequency of respiratory distress syndrome (odds ratio, 0.44; 95% confidence interval, 0.2 to 0.9) and mean ventilator days (odds ratio, 0.44; 95% confidence interval, 0.2 to 0.8) compared with observation alone. All other studied perinatal outcomes analyzed were similar between the groups. Multiple logistic regression confirmed an independent association between a single rescue dose and a reduction in the frequency of respiratory distress syndrome (odds ratio, 0.40; 95% confidence interval, 0.2 to 0.9).

A single rescue dose of betamethasone is associated with a reduction in the frequency of respiratory distress syndrome without an apparent increase in perinatal infectious disease.