The effects of repeat doses of antenatal corticosteroids on maternal adrenal function

OBJECTIVE: The purpose of this study was to determine whether repeated dose s of maternal corticosteroids suppress the maternal hypothalamic-pituitary- adrenal axis. STUDY DESIGN: The low-dose corticotropin stimulation test (1.0 mu g intrave nously) was administered a median of 3 days after the last betamethasone do se to 18 pregnant women who had received at least 2 weekly courses of anten atal betamethasone and to 6 control subjects matched for gestational age wh o had not received antenatal corticosteroids. RESULTS: The mean basal cortisol level was significantly depressed among wo men who had received betamethasone with respect to control subjects (1.9 +/ - 1.5 vs 26.5 +/- 6.2 mu g/dL; P <.001). The maternal cortisol level after corticotropin stimulation was significantly lower in all women who had rece ived betamethasone (P<.001). The mean time to attainment of peak cortisol l evel was significantly longer among women who had received betamethasone th an among control subjects (37 +/- 6.8 vs 27.4 +/- 1.6 minutes; P<.001). CONCLUSIONS: Repeated courses of betamethasone lead to barely detectable ma ternal basal cortisol levels and secondary adrenal insufficiency.