Termination of early pregnancy using flexible, low-dose mifepristone-misoprostol regimens

Various regimens of mifepristone and misoprostol are used in medical abortion. We examined the effect of a change in protocol from a fixed mifepristone-misoprostol interval to a flexible one on the efficacy and uptake of medical abortion. In addition, risk factors of incomplete abortions were evaluated.

Altogether, 1289 medical abortions were carried out between August 2000 and December 2002. Between August 2000 and August 2001, a fixed protocol of 200 mg of oral mifepristone followed by 0.4 mg of vaginally administered misoprostol 2 days later was used. From September 2001, a flexible dosing interval of 1, 2 or 3 days between mifepristone and misoprostol was adopted. At the same time, the upper limit of gestational age was increased from 56 to 63 days.

The uptake of medical abortion increased during the study period and was 45.8% during the use of fixed protocol versus 54.6% during flexible protocol (p<.0001). The rates of complete abortion were 94.9% and 94.4% (n.s.), respectively. Continuing pregnancy was rare (0.7%). Among all subjects, a history of abortion was associated with a significantly lower rate of complete abortion (90.9 vs. 96.3%, p<.002). The other parameters analyzed (age, parity, duration of pregnancy, smoking, mifepristone-misoprostol interval) did not have a significant effect on the rate of complete abortion.

A flexible dosing protocol of mifepristone and misoprostol is effective; thus, its use is encouraged. Previous abortion is a significant risk factor of incomplete medical abortion. Thus, special attention should be paid to the follow-up of these women.