Induction of labour in sheep and in humans by single doses of corticosteroids.

In sheep the administration of single intramuscular injections of dexamethasone into the fetus was shown to be an effective method of initiating parturition. In a controlled trial in women who had gone beyond the 41st week of pregnancy 20 mg betamethasone in saline (six patients) or saline alone (five patients) was injected into the amniotic fluid. In the betamethasone-treated group delivery occurred 78.9 +/- 10.2 (S.D.) hours after injection while in the control group it occurred 323 +/- 62 (S.D.) hours after injection (P < 0.01). In one woman with an anencephalic pregnancy intra-amniotic injection failed to initiate parturition but delivery occurred 88.5 hours after intramuscular injection of betamethasone into the fetus.