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Misoprostol dose and route after mifepristone for early medical abortion: a randomised controlled noninferiority trial

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Please cite this paper as: von Hertzen H, Huong N, Piaggio G, Bayalag M, Cabezas E, Fang A, Gemzell-Danielsson K, Hinh N, Mittal S, Ng E, Chaturachinda K, Pinter B, Puscasiu L, Savardekar L, Shenoy S, Khomassuridge A, Tuyet H, Velasco A, Peregoudov A, for the WHO Research Group on Postovulatory Methods of Fertility Regulation. Misoprostol dose and route after mifepristone for early medical abortion: a randomised controlled noninferiority trial. BJOG 2010;117:1186–1196. Objective 

To compare 400 and 800 μg sublingual or vaginal misoprostol 24 hours after 200 mg mifepristone for noninferiority regarding efficacy in achieving complete abortion for pregnancy termination up to 63 days of gestation. Design 

Placebo-controlled, randomised, noninferiority factorial trial, stratified by centre and length of gestation. Misoprostol 400 or 800 μg, administered either sublingually or vaginally, with follow up after 2 and 6 weeks. Setting 

Fifteen obstetrics/gynaecology departments in ten countries. Population 

Pregnant women (n = 3005) up to 63 days of gestation requesting medical abortion. Methods 

Two-sided 95% CI for differences in failure of complete abortion and continuing pregnancy, with a 3% noninferiority margin, were calculated. Proportions of women with adverse effects were recorded. Outcome measures 

Complete abortion without surgical intervention (main); continuing live pregnancies, induction-to-abortion interval, adverse effects, women’s perceptions (secondary). Results 

Efficacy outcomes analysed for 2962 women (98.6%): 90.5% had complete abortion after 400 μg misoprostol, 94.2% after 800 μg. Noninferiority of 400 μg misoprostol was not demonstrated for failure of complete abortion (difference: 3.7%; 95% CI 1.8–5.6%). The 400-μg dose showed higher risk of incomplete abortion (P < 0.01) and continuing pregnancy (P < 0.01) than 800 μg. Vaginal and sublingual routes had similar risks of failure to achieve complete abortion (P = 0.47, difference in sublingual minus vaginal −0.7%, 95% CI −2.6–1.2%). A similar pattern was observed for continuing pregnancies (P = 0.21). Fewer women reported adverse effects with vaginal than sublingual administration and with the 400-μg dose than the 800-μg dose. Of the women, 94% were satisfied or highly satisfied with the regimens, 53% preferred the sublingual route and 47% preferred the vaginal route. Conclusions 

A 400-μg dose of misoprostol should not replace the 800-μg dose when administered 24 hours after 200 mg mifepristone for inducing abortion in pregnancies up to 63 days. Sublingual and vaginal misoprostol have similar efficacy, but vaginal administration is associated with a lower frequency of adverse effects.

Keywords: Factorial design; medical abortion; mifepristone; misoprostol dose and route

Document Type: Research Article


Affiliations: 1: UNDP/UNFPA/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, Department of Reproductive Health and Research, World Health Organization, Geneva, Switzerland 2: State Research Centre on Maternal and Child Heath, Ulaanbaatar, Mongolia 3: Hospital Docente Gineco-Obstetrico, Eusebio Hernandez, Havana, Cuba 4: International Peace Maternity and Child Health Hospital, Shanghai, China 5: Karolinska Institutet, Stockholm, Sweden 6: National Hospital of Obstetrics and Gynecology, Hanoi, Vietnam 7: All India Institute of Medical Sciences, New Delhi, India 8: Queen Mary Hospital, Hong Kong, Special Administrative Region of China 9: Ramathibodi Hospital, Mahidol University, Bangkok, Thailand 10: University Medical Center, Division Obstetrics and Gynaecology, Ljubljana, Slovenia 11: Center of Public Health, Targu-Mures, Romania 12: National Institute for Research in Reproductive Health, Indian Council of Medical Research, Mumbai, India 13: SAT Hospital, Medical College, Trivandrum, India 14: Zhordania Institute on Human Reproduction, Tbilisi, Georgia 15: Tu Du Hospital, Ho Chi Minh City, Vietnam 16: Hospital America Arias, Havana, Cuba

Publication date: September 1, 2010

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