The role of antenatal corticosteroids in twin pregnancies complicated by preterm birth.

BACKGROUND: Data regarding the effects of antenatal corticosteroids in twin pregnancies are limited because of the insufficient number of women with twins enrolled in randomized controlled trials on antenatal corticosteroids. Furthermore, the interpretation of available data is limited by the fact that the interval from the administration of antenatal corticosteroids to delivery is greater than 7 days in a large proportion of twins, a factor that has been shown to affect the efficacy of antenatal corticosteroids and has not been controlled for in previous studies.

OBJECTIVE: The objective of the study was to compare neonatal mortality and morbidity in preterm twins receiving a complete course of antenatal corticosteroids 1-7 days before birth to those who did not receive antenatal corticosteroids and to compare these outcome effects with those observed in singletons.

STUDY DESIGN: We performed a retrospective cohort study using data collected on singleton and twin neonates born between 24(0/7) and 33(6/7) weeks' gestational age and were admitted to tertiary neonatal units in Canada between 2010 and 2014. A comparison of neonatal outcomes between twin neonates who received a complete course of antenatal corticosteroids 1-7 days before birth (n = 1758) and those who did not receive antenatal corticosteroids (n = 758) and between singleton neonates who received a complete course of antenatal corticosteroids 1-7 days before birth (n = 4638) and those did not receive antenatal corticosteroids (n = 2312) was conducted after adjusting for gestational age, sex, hypertension, outborn status, small for gestational age, parity, and cesarean birth. Adjusted odds ratios and 95% confidence intervals for various neonatal outcomes were calculated.

RESULTS: Administration of a complete course of antenatal corticosteroids within 1-7 days before birth in both twins and singletons was associated with similar reduced odds of neonatal death (for twins adjusted odds ratio 0.42 [95% confidence interval, 0.24-0.76] and for singletons adjusted odds ratios, 0.38 [95% confidence interval, 0.28-0.50]; P = .7 for comparison of twins vs singletons), mechanical ventilation (for twins adjusted odds ratio, 0.47 [95% confidence interval, 0.35-0.63] and for singletons adjusted odds ratio, 0.47 [95% confidence interval, 0.41-0.55]; P = .9), respiratory distress syndrome (for twins adjusted odds ratio, 0.53 [95% confidence interval, 0.40-0.69], and for singletons adjusted odds ratio, 0.54 [95% confidence interval, 0.47-0.62]; P = .9) and severe neurological injury (for twins adjusted odds ratio, 0.50 [95% confidence interval, 0.30-0.83] and for singletons adjusted odds ratio, 0.45 [95% confidence interval, 0.34-0.59]; P = .7). Administration of a complete course of antenatal corticosteroids was not associated with a reduced odds of bronchopulmonary dysplasia, severe retinopathy of prematurity, or necrotizing enterocolitis in both twins and singletons.

CONCLUSION: Administration of a complete course of antenatal corticosteroids 1-7 days before birth in twin pregnancies is associated with a clinically significant decrease in neonatal mortality, short-term respiratory morbidity, and severe neurological injury that is similar in magnitude to that observed among singletons.