Raymond Elizabeth G, Weaver Mark A
Family Health International, Research Triangle Park, NC 27709, USA.
Contraception. 2008 May;77(5):333-6. doi: 10.1016/j.contraception.2008.02.001. Epub 2008 Mar 21.
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.
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 1 year. In this secondary analysis, we examined ECP and contraceptive use in the cycles ending in pregnancy in that trial.
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.
Unrestricted access to ECPs in this trial may have increased the frequency of coital acts with the potential to lead to pregnancy.
先前关于紧急避孕药（ECP）的试验发现，在以怀孕告终的月经周期中，与有标准获取途径的女性相比，使用增强药物获取途径干预措施的女性中ECP的使用更为普遍。我们分析了其中一项此类试验的数据，以探讨这一发现是否对干预措施对怀孕风险行为的影响有启示。
在我们最近的一项随机试验中，干预组在有需求之前提前获得不限量免费的ECP，而对照组参与者在需要时按常规费用获取药物。对参与者进行了1年的随访。在这项二次分析中，我们研究了该试验中以怀孕告终的周期中ECP和避孕药具的使用情况。
干预组的怀孕似乎比对照组更有可能被归类为“可能”或“也许”的ECP失败（干预组74例中有12例，对照组74例中有1例；p = 0.012），并且更有可能发生在使用效果较差的避孕药具的情况下。
在该试验中不受限制地获取ECP可能增加了可能导致怀孕的性交行为的频率。
