Frequency of same-day contraceptive initiation, recent unprotected intercourse, and pregnancy risk: a prospective cohort study of multiple contraceptive methods

Same-day start removes barriers to contraceptive initiation and may reduce the risk of unintended pregnancy. It may be appropriate for all contraceptive methods, but we lack data comparing methods. This study aimed to assess the frequency of same-day start with 6 contraceptive methods among new contraceptive users and describe the efficacy of same-day start in terms of first-cycle pregnancy risk overall and by each method. Using prospective data from the HER Salt Lake Contraceptive Initiative, we identified and assessed outcomes for participants initiating a new method of contraception beyond the first 7 days of their menstrual cycle (same-day start). Enrolled participants at 4 family planning clinics in Salt Lake County, Utah between September 2015 and March 2017 received their method of choice regardless of their cycle day or recent unprotected intercourse. All participants self-reported last menstrual period data and unprotected intercourse events in the previous 2 weeks. We excluded participants who received care immediately after or within 2 weeks of abortion care. Clinical electronic health records provided information on contraceptive method initiation and use of oral emergency contraception. Participants reported pregnancy outcomes in 1-, 3-, and 6-month follow-up surveys with clinic verification to identify any pregnancy resulting from same-day initiation. The primary outcomes report the frequency of same-day start use and first-cycle pregnancy risk among same-day start users of all contraceptive methods. The secondary outcomes include frequency of and pregnancy risk in the first cycle of use among same-day start contraception users by method. We also report the frequency of unprotected intercourse within 5 days and 6 to 14 days of contraception initiation, frequency of concomitant receipt of oral emergency contraception with initiation of ongoing contraception, and pregnancy risk with these exposures. We analyzed pregnancy risk for each contraceptive method initiated on the same day and assessed the simultaneous use of oral emergency contraception. Of the 3568 individuals enrolled, we identified most as same-day start users (n=2575/3568; 72.2%), with 1 in 8 of those reporting unprotected intercourse in the previous 5 days (n=322/2575; 12.5%) and 1 in 10 reporting unprotected intercourse 6 to 14 days before contraceptive method initiation (n=254/2575; 9.9%). We identified 11 pregnancies among same-day start users (0.4%; 95% confidence interval, 0.