Medical Abortion and the Risk of Subsequent Adverse Pregnancy Outcomes

Abstract

First-trimester surgical abortion is established as a safe procedure, but relatively little is known about whether and how so-called medical abortion—achieved using one or more medications—affects subsequent pregnancies. Current regimens for medical abortion include misoprostol alone, methotrexate followed by misoprostol and, by far the commonest method, mifepristone followed by misoprostol. The investigators analyzed a nationwide Danish cohort to learn whether medical abortion carries an increased risk of ectopic pregnancy, spontaneous abortion, preterm birth (before 37 weeks' gestation, and/or low birth weight [less than 2500 gm]) compared with surgical abortion. Among 11,814 pregnancies in women having a previous first-trimester abortion were 2710 having a medical abortion and 9104 having a surgical procedure. The abortions, taking place in the years 1999–2004, all were performed for nonmedical reasons. There were 274 ectopic pregnancies in this population, 1426 spontaneous abortions, 552 preterm births, and 478 instances of low birth weight. After adjusting for maternal age, parity, interpregnancy interval, site of residence, cohabitation status, and gestational age at the time of abortion, none of the 4 adverse outcomes were significantly more frequent after medical than after surgical abortion. The 2 groups did not differ significantly in mean gestational age at birth or mean birth weight. Gestational age at the time of abortion did not correlate significantly with any of the adverse outcomes. This cohort study gives no evidence that a previous medical abortion, as compared with a past surgical abortion, increases the risk of adverse obstetrical outcomes. At least with regard to the subsequent risk of ectopic pregnancy, spontaneous abortion, preterm birth, and low birth weight, medical abortion is as safe as, or safer than, surgical abortion.