Mifepristone-induced abortion and placental complications in subsequent pregnancy

The aim of the study was to explore the effect of first-trimester mifepristone-induced abortion (MA) on placental complications in subsequent pregnancy.

Two cohorts of nulliparous pregnant women were recruited in China during early pregnancy, one with a history of one MA and the other with no abortion (NA). Women were followed up until delivery.

The incidence proportions of abruptio placenta, placenta previa, placenta accreta and retained placenta in the MA group (4673) and NA group (4690) were, respectively, 0.5 and 0.3, 0.8 and 0.9, 0.5 and 0.5, and 0.7 and 0.8% (all differences non-significant). After adjustment for center, age, education, occupation, residence, income, BMI and type of delivery, the incidence rates of placenta previa, accreta and retained placenta in the MA and NA groups showed no significant differences. The risk of abruptio placenta in women with a MA was nearly double that of women with no abortion, although this apparent increased risk was not statistically significant. Furthermore, this increased risk of abruptio placenta was found only in those with a gestational age >6 weeks at abortion (aOR: 2.46; 95% CI: 1.00-6.04), a curettage after abortion (aOR: 3.00; 95% CI: 1.25-7.20) or a longer inter-pregnancy interval (P-value for trend: 0.022).

Mifepristone-induced abortion itself is not associated with placental complications in subsequent pregnancy, but other factors related to medical abortion-such as a gestational age >6 weeks at abortion, a curettage after abortion, and a longer interpregnancy interval-may increase the risk of abruptio placenta.