Single versus additional courses of intramuscular corticosteroids for lung maturation has been the topic of two major trials. Although both found repeated courses to be beneicial in reducing neonatal respiratory morbidity rates, the long-term consequences were much diferent. In one randomized study by Crowther and associates (2007), all women at risk for preterm birth were given a primary course of betamethasone. Women were then given serial weekly doses of 11e.4 mg of betamethasone for persistent risk or were given placebo. hese investigators found no adverse efects in the infants followed to age 2 years. Wapner and coworkers (2007) studied infants born to 495 women who were randomly assigned to receive a single corticosteroid course that contained two doses or assigned to repeated courses that were given weekly. A nonsignificant rise in the cerebral palsy rate was identified in infants exposed to repeated courses. The doubled betamethasone dose in this study was worrisome because some experimental evidence supports the view that adverse efects are dose dependent (Bruschettini, 2006). Stiles (2007) summarized these two studies as "early gain, long-term questions." We agree, and at Parkland Hospital, we follow the recommendation by the American College of Obstetricians and Gynecologists (2017a) for singlecourse therapy.
his refers to administration of a second corticosteroid dose when delivery becomes imminent and more than 7 days have elapsed since the initial dose. In one randomized trial, 326 women received placebo or a single 12-mg dose of betamethasone (Peltoniemi, 2007). Paradoxically, the rescue dose of betamethasone increased the risk of RDS. In another randomized study of 437 women with gestations <33 weeks, Garite and associates (2009) reported significantly lower rates of respiratory complications and neonatal composite morbidity with rescue corticosteroids versus placebo. Rates of perinatal mortality and other morbidities, however, did not difer. Last, McEvoy and colleagues (2010) found that treated infants had improved respiratory compliance.
Garite and coworkers (2009) randomly assigned 437 women with singletons or twins <33 weeks' gestation and with intact membranes to one rescue course of either betamethasone or dexamethasone or placebo. These women had all previously completed a single course of corticosteroids before 30 weeks' gestation and at least 14 days before the rescue course. RDS developed in 41 percent of the newborns given rescue corticosteroids compared with 62 percent of those randomized to placebo. Rates of other morbidities attributable to prematurity did not difer. In a metaanalysis, Crowther and colleagues (201e1) concluded that a single course of corticosteroids should be considered in women whose prior course was administered at least 7 days previously and who were <34 weeks' gestation. The American College of Obstetricians and Gynecologists (2017 a) has taken the position that a single rescue course of antenatal corticosteroids be considered in women before 34 weeks whose prior course was administered at least 7 days previously. Efects of rescue therapy beyond 34 weeks are currently unknown. At Parkland Hospital, we currently do not provide additional courses of corticosteroids beyond the initial single-course therapy.