Mifepristone-induced abortion and vaginal bleeding in subsequent pregnancy.

Background: The aim of this study is to explore the effect of first-trimester mifepristone-induced abortion on vaginal bleeding in subsequent pregnancy.

Study Design: This observational cohort study was conducted during 1998-2001 at antenatal clinics in Beijing, Chengdu, and Shanghai, China. The study enrolled 4,931 women with one previous mifepristone-induced abortion, 4,925 women with no history of induced abortion, and 4,800 women with one previous surgical abortion and followed them through pregnancy and childbirth.

Results: The rates of vaginal bleeding in pregnant women with a history of medical abortion, no abortion, and surgical abortion were 16.5%, 13.9%, and 17.3%, respectively. The women with medical abortion had a higher risk (adjusted relative risk (aRR)=1.17, 95% confidence interval (CI): 1.07, 1.29) of vaginal bleeding compared with those with no abortion but similar risk to prior surgical abortion. When the correlation between medical abortion and vaginal bleeding was examined by period, increased risk was observed only in the early period (<16 gestational weeks) (aRR=1.25, 95% CI: 1.12, 1.39). The comparison between subgroups of medical abortion and no abortion showed that the observed risks increased particularly in those with abortion at gestational age ≤ 7 weeks (aRR=1.33, 95% CI: 1.18, 1.49), those followed by a postabortion curettage (aRR=1.58, 95% CI: 1.37, 1.84) or complications (aRR=1.99, 95% CI: 1.67, 2.37). There was no difference between women with medical abortion and women with surgical abortion in the occurrence of vaginal bleeding for either period.

Conclusions: One previous mifepristone-induced abortion increased the risk of vaginal bleeding in early gestation period of subsequent pregnancy compared with no abortion, especially if abortion occurred before 7 weeks of gestation and was followed by a curettage or complications.