Abstract: Five studies were included. No new eligible studies have been found since the review was initially conducted. Method discontinuation was similar between groups in all trials. Bleeding patterns and side effects were similar in trials that compared immediate with conventional start. In a study of depot medroxyprogesterone acetate (DMPA), immediate start of DMPA showed fewer pregnancies than a 'bridge' method before DMPA (OR 0.36; 95% CI 0.16 to 0.84). Further, more women in the immediate-DMPA group were very satisfied versus those with a 'bridge' method (OR 1.99; 95% CI 1.05 to 3.77). A trial of two immediate-start methods showed the vaginal ring group had less prolonged bleeding (OR 0.42; 95% CI 0.20 to 0.89) and less frequent bleeding (OR 0.23; 95% CI 0.05 to 1.03) than COC users. The ring group also reported fewer side effects. Also, more immediate ring users were very satisfied than immediate COC users (OR 2.88; 95% CI 1.59 to 5.22). We found limited evidence that immediate start of hormonal contraception reduces unintended pregnancies or increases method continuation. However, the pregnancy rate was lower with immediate start of DMPA versus another method. Some differences were associated with contraceptive type rather than initiation method, i.e., immediate ring versus immediate COC. More studies are needed of immediate versus conventional start of the same hormonal contraceptive.

Plain-language summary: In August 2012, did computer searches for randomized controlled trials of the quick-start method for pills and other hormonal birth control. We contacted researchers to find other studies. We included trials that compared quick start to the usual start of birth control. Also included were studies that compared quick start of different types of hormonal birth control with each other. Birth control methods could have the hormones estrogen and progestin (combined hormonal birth control) or just the progestin. Five studies were included. In a study of 'depo,' which is given as a shot, fewer women with quick start of depo became pregnant than those who used another method for 21 days before depo. In this review, the numbers of women who stopped using their birth control method early were similar between groups in all trials. In the depo trial, more women with quick start of depo were very satisfied. A trial of two quick-start methods showed women with the vaginal ring had less long-term bleeding and less frequent bleeding than those with pills. For six side effects, including changes in breasts, mood, and nausea, quick start of the ring showed fewer problems than quick start of pills. For satisfaction in that trial, more women in the ring group were very satisfied with their method of birth control. We found little evidence that quick start leads to fewer pregnancies or fewer women stopping early. However, fewer women on quick start of depo became pregnant than the women who started with another method. Other differences were between types of birth control rather than start times. Women using the vaginal ring had fewer problems than women using birth control pills. More studies are needed comparing quick start versus usual start of the same hormonal birth control method.