A comparison of two glucocorticoid regimens for acceleration of fetal lung maturation in premature labor.

This study compares fetal corticoid response from conventional dose (12.0 mg) intramuscular betamethasone to large dose (1,000 mg) intravenous cortisol administered to women in premature labor for acceleration of fetal lung maturity. To compare these two regimens, 14 women selected at random were treated in groups of seven with either cortisol or betamethasone. Peripheral levels of unconjugated estriol were measured by specific radioimmunoassay prior to the cortisol dose and at 1, 4, 8, and 12 hours following the dose. The rate of corticoid delivery to the fetal hypothalamic-adrenal axis was estimated by the per cent suppression of unconjugated estriol at each post-treatment interval. Least-squares regression lines fitted (P less than 0.01) for each regimen were compared for time saved (delta t) when cortisol was used. Mean delta t (1, 4, 8, and 12 hours) was 9.0 +/- 0.2 S.E.M. hours. It is concluded that: (1) Intravenous cortisol delivers a fetal corticoid effect that is significantly more rapid in onset and more profound in magnitude than does intramuscular betamethasone and that (2) the cortisol regimen is probably better suited to the acceleration of fetal lung maturation in premature labor when time is short and rapid action is essential.