Prior copper intrauterine device use and reproductive outcomes after embryo transfer in IVF/ICSI cycles: a propensity score–matched cohort study

BackgroundThe copper intrauterine device (Cu-IUD) is a widely used long-term contraceptive method. However, whether prior Cu-IUD use, including long-term exposure, affects reproductive and neonatal outcomes after assisted reproductive technology (ART) remains unclear. This study evaluated the association between prior Cu-IUD use and outcomes after embryo transfer in IVF/ICSI cycles.MethodsThis retrospective cohort study included 62,422 embryo transfer cycles (27,692 fresh and 34,730 frozen–thawed embryo transfer cycles) performed between September 2008 and December 2023. Of these, 3,151 cycles involved women with a history of Cu-IUD use and 59,271 cycles involved women without any IUD history. Propensity score matching (1:2) was performed separately for fresh and frozen embryo transfer cohorts. The primary outcome was live birth rate per embryo transfer. Secondary outcomes included biochemical pregnancy, clinical pregnancy, miscarriage, multiple birth, and low birth weight.ResultsAfter matching, baseline characteristics were well balanced between groups. In fresh embryo transfer cycles, live birth rates were comparable between women with and without prior Cu-IUD use (28.0% vs. 27.7%; adjusted RR 1.01, 95% CI 0.91–1.11). Similar results were observed in frozen embryo transfer cycles (23.1% vs. 23.6%; adjusted RR 0.97, 95% CI 0.87–1.07). No significant differences were observed in biochemical pregnancy, clinical pregnancy, miscarriage, multiple birth, or low birth weight between groups in either fresh or frozen embryo transfer cycles. Stratified analyses showed no clinically relevant effect modification by age, AMH, or BMI.ConclusionWithin this study, prior Cu-IUD use, including long-term use, was not found to be associated with adverse reproductive or neonatal outcomes after embryo transfer in IVF/ICSI cycles. These results do not provide evidence to support additional ART interventions based solely on prior Cu-IUD history.