Steiner Markus J, Kwok Cynthia, Stanback John, Byamugisha Josaphat K, Chipato Tsungai, Magwali Thulani, Mmiro Francis, Rugpao Sungwal, Sriplienchan Somchai, Morrison Charles
Family Health International, Research Triangle Park, NC 27709, USA.
Contraception. 2008 Jun;77(6):410-4. doi: 10.1016/j.contraception.2008.01.017. Epub 2008 Apr 10.
Progestin-only injectable contraceptives continue to gain in popularity, but uncertainty remains about pregnancy risk among women late for reinjection. The World Health Organization (WHO) recommends a "grace period" of 2 weeks after the scheduled 13-week reinjection. Beyond 2 weeks, however, many providers send late clients home to await menses.
A prospective cohort study in Uganda, Zimbabwe and Thailand followed users of depot-medroxyprogesterone acetate (DMPA) for up to 24 months. Users were tested for pregnancy at every reinjection, allowing analysis of pregnancy risk among late comers.
The analysis consists of 2290 participants contributing 13,608 DMPA intervals. The pregnancy risks per 100 women-years for "on time" [0.6; 95% confidence interval (CI), 0.33-0.92], "2-week grace" (0.0; 95% CI, 0.0-1.88) and "4-week grace" (0.4; 95% CI, 0.01-2.29) injections were low and virtually identical.
Extending the current WHO grace period for DMPA reinjection from 2 to 4 weeks does not increase pregnancy risk and could increase contraceptive continuation.
仅含孕激素的注射用避孕药持续受到欢迎，但对于延迟再次注射的女性的妊娠风险仍存在不确定性。世界卫生组织（WHO）建议在预定的13周再次注射后有2周的“宽限期”。然而，超过2周后，许多医疗服务提供者会让延迟就诊的患者回家等待月经。
在乌干达、津巴布韦和泰国进行的一项前瞻性队列研究对醋酸甲羟孕酮长效注射剂（DMPA）使用者进行了长达24个月的随访。在每次再次注射时对使用者进行妊娠检测，以便分析延迟就诊者的妊娠风险。
分析包括2290名参与者，共提供了13608个DMPA使用间隔。“按时”（每100妇女年妊娠风险为0.6；95%置信区间[CI]，0.33 - 0.92）、“2周宽限期”（0.0；95%CI，0.0 - 1.88）和“4周宽限期”（0.4；95%CI，0.01 - 2.29）注射的妊娠风险较低且几乎相同。
将世界卫生组织目前关于DMPA再次注射的宽限期从2周延长至4周不会增加妊娠风险，并且可能会提高避孕药具的持续使用率。
