Mifepristone (RU486) and therapeutic late pregnancy termination: a double-blind study of two different doses

An antiprogesterone, mifepristone (RU486), was administeredto 35 patients undergoing a therapeutic interruption of pregnancyduring the second and third trimester for maternal or fetalindications. A randomized double-blind study test was perfonnedusing 150 and 450 mg of mifepristone as pretreatment prior toprostaglandins. No toxicity or maternal morbidity were recorded.In three patients the onset of labour occurred spontaneouslybefore prostaglandin administration. Mifepristone produced amodification in the consistency of the cervix with a statisticalimprovement in cervical calibration in the two groups, but thecervical effect was independent of the dose.