A Cochrane review included 40 studies. Misoprostol in combination with mifepristone was more effective than misoprostol alone (RR 12.13, 95% CI 1.43 to 102.61; 1 trial, n=64). In combination with mifepristone, the induction to abortion interval was shorter with vaginal misoprostol compared to oral misoprostol (mean difference 7.03, 95% CI -0.13 to 14.20; 2 trials, n=237). The combination of mifepristone plus misoprostol was as effective as mifepristone plus gemeprost. Misoprostol was preferably administered vaginally, although among multiparous women sublingual administration appeared equally effective. No randomised trials comparing doses of misoprostol were identified; however low doses of misoprostol appear to be associated with fewer side-effects while moderate doses appear to be more efficient in completing abortion. Four RCTs showed that the induction to abortion interval with 3-hourly vaginal administration of prostaglandins is shorter than 6-hourly administration without an increase in side-effects.