Effect of an emergency contraceptive pill intervention on pregnancy risk behavior

Objective: Previous trials of emergency contraceptive pills (ECPs) found that in menstrual cycles ending in pregnancy, ECP use was more common among women exposed to interventions that enhanced access to the medication than among women with standard access. We examined data from one such trial to explore whether this finding has implications regarding the effect of the intervention on pregnancy risk behavior. Methods: In our recent randomized trial, the intervention group received unlimited free ECPs in advance of need, whereas control participants obtained the medication when needed at usual cost. Participants were followed up for I year. In this secondary analysis, we examined ECP and contraceptive use in the cycles ending in pregnancy in that trial. Results: Pregnancies in the intervention group appeared to have been more likely than those in the control group to be classified as "probably" or "possibly" ECP failures (12/74 in the intervention group vs. 1/74 in the control group; p=.012) and more likely to have occurred in the context of use of less efficacious contraceptives. Conclusion: Unrestricted access to ECPs in this trial may have increased the frequency of coital acts with the potential to lead to pregnancy. (c) 2008 Elsevier Inc. All rights reserved.