A randomized double-blind placebo-controlled study to assess the effect of oral contraceptive pills on the outcome of medical abortion with mifepristone and misoprostol

This was a randomized double-blind placebo-controlled trial to determine the effect of oral contraceptive (OC) pills taken immediately after medical abortion on the duration of bleeding and complete abortion rate. Two hundred women in the first 49 days of pregnancy were given 200 mg mifepristone orally followed by 400 microg misoprostol vaginally 48 h later. One day later, they were randomized to receive either OC pills (30 microg of ethinyl oestradiol and 0.15 mg of levonorgestrel per tablet) or placebo for 21 days. The complete abortion rates were 98% in the OC group and 99% in the placebo group. The median duration of bleeding was similar: 17 (range: 5-57) days in the OC group and 16 (range: 6-55) days in the placebo group. In the OC group there was a small but significant fall in the haemoglobin concentration by 14 days (5.3 g/dl) after administration of mifepristone. The incidence of side-effects was similar in the two groups. We conclude that the use of OC pills does not decrease the duration of bleeding after medical abortion nor does it affect the abortion rate.