Injectable contraception: what should the longest interval be for reinjections?

BackgroundProgestin-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.Study designA 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.ResultsThe 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.ConclusionExtending the current WHO grace period for DMPA reinjection from 2 to 4 weeks does not increase pregnancy risk and could increase contraceptive continuation.