Health care providers often tell women to wait until their next menstrual cycle to begin birth control pills. The main reason is to avoid using birth control during an undetected pregnancy. Another method involves starting the pills right away ('immediate start' or 'quick start'). Another birth control method should be used as back-up for the first seven days. Unclear issues are whether quick start of hormonal birth control works as well as the usual start and whether women like it. The quick start method might improve women's use of hormonal birth control.
We 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,' a progestin-only injection, 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 strong 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.