Comparison of rates of adverse events in adolescent and adult women undergoing medical abortion: population register based study

OBJECTIVE To determine the risks of short term adverse events in adolescent and older women undergoing medical abortion. DESIGN Population based retrospective cohort study. SETTING Finnish abortion register 2000-6. PARTICIPANTS All women (n = 27,030) undergoing medical abortion during 2000-6, with only the first induced abortion analysed for each woman. MAIN OUTCOME MEASURES Incidence of adverse events (haemorrhage, infection, incomplete abortion, surgical evacuation, psychiatric morbidity, injury, thromboembolic disease, and death) among adolescent (<18 years) and older (≥ 18 years) women through record linkage of Finnish registries and genital Chlamydia trachomatis infections detected concomitantly with abortion and linked with data from the abortion register for 2004-6. RESULTS During 2000-6, 3024 adolescents and 24,006 adults underwent at least one medical abortion. The rate of chlamydia infections was higher in the adolescent cohort (5.7% v 3.7%, P < 0.001). The incidence of adverse events among adolescents was similar or lower than that among the adults. The risks of haemorrhage (adjusted odds ratio 0.87, 95% confidence interval 0.77 to 0.99), incomplete abortion (0.69, 0.59 to 0.82), and surgical evacuation (0.78, 0.67 to 0.90) were lower in the adolescent cohort. In subgroup analysis of primigravid women, the risks of incomplete abortion (0.68, 0.56 to 0.81) and surgical evacuation (0.75, 0.64 to 0.88) were lower in the adolescent cohort. In logistic regression, duration of gestation was the most important risk factor for infection, incomplete abortion, and surgical evacuation. CONCLUSIONS The incidence of adverse events after medical abortion was similar or lower among adolescents than among older women. Thus, medical abortion seems to be at least as safe in adolescents as it is in adults.