Mifepristone-induced early abortion and outcome of subsequent wanted pregnancy.

Follow-up information on subsequent pregnancies after mifepristone (RU486)-induced abortion is scarce. The authors examined whether one mifepristone-induced first-trimester abortion affects the outcome of a subsequent wanted pregnancy. In a study conducted in 1998-2001 at antenatal clinics in Beijing, Chengdu, and Shanghai, China, the authors enrolled 4,925 women with no history of induced abortion, 4,931 women with one previous mifepristone-induced abortion, and 4,800 women with one previous surgical abortion and followed them through pregnancy and childbirth. The adjusted odds ratio for preterm delivery in women with one mifepristone abortion compared with women with no abortion was 0.77 (95% confidence interval: 0.61, 0.98). Although the mean birth weight of infants born to women with mifepristone abortion was 33 g (95% confidence interval: 17, 49) higher than that of infants born to women with no abortion, the frequencies of low birth weight and mean lengths of pregnancy were similar. There were no significant differences in risk of preterm delivery, frequency of low birth weight, or mean infant birth weight in the comparisons of women with previous mifepristone abortion and women with surgical abortion. This study suggests that one early abortion induced by mifepristone in nulliparous women has no adverse effects on the outcome of a subsequent pregnancy.