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

OBJECTIVE: The purpose of this study was to determine whether repeated doses of maternal corticosteroids suppress the maternal hypothalamic-pituitary-adrenal axis.

STUDY DESIGN: The low-dose corticotropin stimulation test (1.0 microg intravenously) was administered a median of 3 days after the last betamethasone dose to 18 pregnant women who had received at least 2 weekly courses of antenatal betamethasone and to 6 control subjects matched for gestational age who had not received antenatal corticosteroids.

RESULTS: The mean basal cortisol level was significantly depressed among women who had received betamethasone with respect to control subjects (1.9 +/- 1.5 vs 26.5 +/- 6.2 microg/dL; P <.001). The maternal cortisol level after corticotropin stimulation was significantly lower in all women who had received betamethasone (P <. 001). The mean time to attainment of peak cortisol level was significantly longer among women who had received betamethasone than among control subjects (37 +/- 6.8 vs 27.4 +/- 1.6 minutes; P <.001).

CONCLUSIONS: Repeated courses of betamethasone lead to barely detectable maternal basal cortisol levels and secondary adrenal insufficiency.