Pregnancy Risk by Frequency and Timing of Unprotected Intercourse Before Intrauterine Device Placement for Emergency Contraception.

OBJECTIVE To assess pregnancy risk after intrauterine device (IUD) placement by the number and timing of unprotected intercourse episodes in the prior 14 days. METHODS This was a secondary analysis of a randomized trial that compared the copper T380A IUD and levonorgestrel 52-mg intrauterine system for emergency contraception. At enrollment, participants had a negative urine pregnancy test result and reported the frequency and timing of any unprotected intercourse in the preceding 14 days. We assessed pregnancies 1 month after IUD placement and compared pregnancy risk by single or multiple unprotected intercourse episodes and by timing (5 or fewer days before IUD placement or 6 or more days before). RESULTS Among the 655 participants, one pregnancy occurred in a patient who reported intercourse once 48 hours before IUD placement. Multiple unprotected intercourse episodes were reported by 286 participants (43.7%), and 95 participants (14.4%) reported at least one unprotected intercourse episode 6 or more days before IUD placement. No pregnancies occurred among those with multiple unprotected intercourse episodes (0%, 97.5% CI 0-1.3%) or with any unprotected intercourse episode 6-14 days before IUD placement (0.0%, 97.5% CI 0.0-3.8%). Pregnancy risk difference did not significantly differ by single compared with multiple unprotected intercourse episodes (0.3%, 95% CI -0.3% to 0.8%), nor by unprotected intercourse 5 or fewer days before IUD placement or 6 or more days before (0.2%, 95% CI -0.2% to 0.5%). CONCLUSION With a negative urine pregnancy test result at IUD placement, 1-month pregnancy risk remains low, regardless of frequency or timing of unprotected intercourse in the prior 14 days. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov, NCT02175030.