Polis C B, Schaffer K, Blanchard K, Glasier A, Harper C C, Grimes D A
Johns Hopkins Bloomberg School of Public Health, Department of Population, Family and Reproductive Health, Room W4510, 615 N. Wolfe St, Baltimore, Maryland 21205, USA.
Cochrane Database Syst Rev. 2007 Apr 18;2007(2):CD005497. doi: 10.1002/14651858.CD005497.pub2.
Emergency contraception can prevent pregnancy when taken after unprotected intercourse. Obtaining emergency contraception within the recommended time frame is difficult for many women. Advance provision, in which women receive a supply of emergency contraception before unprotected sex, could circumvent some obstacles to timely use.
To summarize randomized controlled trials evaluating advance provision of emergency contraception to explore effects on pregnancy rates, sexually transmitted infections, and sexual and contraceptive behaviors.
In August 2006, we searched CENTRAL, EMBASE, POPLINE, MEDLINE via PubMed, and a specialized emergency contraception article database. We also searched reference lists and contacted experts to identify additional published or unpublished trials.
We included randomized controlled trials comparing advance provision and standard access, which was defined as any of the following: counseling which may or may not have included information about emergency contraception, or provision of emergency contraception on request at a clinic or pharmacy.
We evaluated all identified titles and abstracts found for potential inclusion. Two reviewers independently abstracted data and assessed study quality. We entered and analyzed data using RevMan 4.2.8. We calculated odds ratios with 95% confidence intervals for dichotomous data and weighted mean differences with 95% confidence intervals for continuous data.
Eight randomized controlled trials met our criteria for inclusion, representing 6389 patients in the United States, China and India. Advance provision did not decrease pregnancy rates (OR 1.0; 95% CI: 0.78 to 1.29 in studies for which we included twelve month follow-up data; OR 0.91; 95% CI: 0.69 to 1.19 in studies for which we included six month follow-up data; OR 0.49; 95% CI: 0.09 to 2.74 in a study with three month follow up data), despite increased use (single use: OR 2.52; 95% CI 1.72 to 3.70; multiple use: OR 4.13; 95% CI 1.77 to 9.63) and faster use (weighted mean difference (WMD) -14.6 hours; 95% CI -16.77 to -12.4 hours). Advance provision did not lead to increased rates of sexually transmitted infections (OR 0.99; 95% CI 0.73 to 1.34), increased frequency of unprotected intercourse, nor changes in contraceptive methods. Women who received emergency contraception in advance were equally as likely to use condoms as other women.
AUTHORS' CONCLUSIONS: Advance provision of emergency contraception did not reduce pregnancy rates when compared to conventional provision. Advance provision does not negatively impact sexual and reproductive health behaviors and outcomes. Women should have easy access to emergency contraception, because it can decrease the chance of pregnancy. However, the interventions tested thus far have not reduced overall pregnancy rates in the populations studied.
紧急避孕在无保护性交后服用可预防妊娠。许多女性难以在推荐时间内获得紧急避孕药物。预先提供,即女性在无保护性行为前获得紧急避孕药物供应,可规避一些及时使用的障碍。
总结评估紧急避孕预先提供的随机对照试验,以探讨其对妊娠率、性传播感染以及性和避孕行为的影响。
2006年8月,我们通过PubMed检索了Cochrane系统评价数据库、EMBASE、人口与计划生育数据库、MEDLINE以及一个专门的紧急避孕文章数据库。我们还检索了参考文献列表并联系专家以识别其他已发表或未发表的试验。
我们纳入了比较预先提供和标准获取方式的随机对照试验,标准获取方式定义为以下任何一种:可能包含或不包含紧急避孕信息的咨询,或在诊所或药房应要求提供紧急避孕药物。
我们评估了所有识别出的可能纳入的标题和摘要。两名审阅者独立提取数据并评估研究质量。我们使用RevMan 4.2.8录入和分析数据。对于二分数据,我们计算了比值比及95%置信区间;对于连续数据,我们计算了加权均数差值及95%置信区间。
八项随机对照试验符合我们的纳入标准,涉及美国、中国和印度的6389名患者。预先提供并未降低妊娠率(对于纳入十二个月随访数据的研究,比值比为1.0;95%置信区间:0.78至1.29;对于纳入六个月随访数据的研究,比值比为0.91;95%置信区间:0.69至1.19;对于一项有三个月随访数据的研究,比值比为0.49;95%置信区间:0.09至2.74),尽管使用增加(单次使用:比值比为2.52;95%置信区间1.72至3.70;多次使用:比值比为4.13;95%置信区间1.77至9.63)且使用更快(加权均数差值为-14.6小时;95%置信区间-16.77至-12.4小时)。预先提供并未导致性传播感染率增加(比值比为0.99;95%置信区间0.73至1.34),未导致无保护性交频率增加,也未导致避孕方法改变。预先获得紧急避孕药物的女性使用避孕套的可能性与其他女性相同。
与传统提供方式相比,紧急避孕预先提供并未降低妊娠率。预先提供对性和生殖健康行为及结果没有负面影响。女性应能方便地获得紧急避孕药物,因为它可降低妊娠几率。然而,迄今为止所测试的干预措施尚未降低所研究人群的总体妊娠率。