Abstract
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.