Medically induced abortions were just as safe as surgical abortions with regard to the outcomes of future pregnancies, according to a large study conducted in Denmark.
The population-based study of almost 12,000 pregnancies that occurred subsequent to elective abortions in the first trimester showed no significant differences in the risk of ectopic pregnancy, preterm birth, miscarriage, or low birth weight, reported study authors Dr. Jun Zhang, of the National Institute of Child Health and Human Development, and colleagues (N. Engl. J. Med. 2007;357;648–53).
The investigators examined data on all women living in Denmark who had undergone an abortion for nonmedical reasons between 1999 and 2004 and had at least one subsequent pregnancy between 1999 and 2005. The first pregnancy after each abortion was included in the study.
Data for each of the 11,682 women in the study were linked to the Danish National Birth Registry and National Patient Registry.
Of the 11,814 pregnancies in these women, 9,104 were preceded by a surgical abortion, and 2,710 were preceded by a medical abortion involving mifepristone and misoprostol, or misoprostol alone.
Most of the subsequent pregnancies (85%) resulted in live births; there were 1,486 miscarriages (13%), 274 ectopic pregnancies (2%), and 36 stillbirths (0.3%).
The incidence of ectopic pregnancy, miscarriage, preterm birth (defined as gestation less than 37 completed weeks), and low birth weight (defined as less than 2,500 g) was not significantly different between the groups, even after the investigators adjusted for maternal age, parity, interpregnancy interval, maternal residence, cohabitation status, and gestational age at the time of the abortion. (See table below.)
There were too few stillbirths to make a meaningful comparison between groups, the authors said.
The findings differ from those of a previous study, which showed a significant association between medical abortion and ectopic pregnancy (Am. J. Epidemiol. 2003;157:185–94).
However, that case-control study relied on self-report of abortion and pregnancy outcomes, rather than a clinical registry, Dr. Zhang and coauthors pointed out.
A recent Chinese multicenter cohort study found results similar to the Danish study, the authors noted. That study of almost 10,000 women found no difference in low birth weight or preterm birth between women who had a previous surgical or medical abortion (Am. J. Epidemiol. 2004;160:110–7).
None of the investigators in the Danish study reported conflicts of interest relative to the research.
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