Intrauterine Devices and Risk of Ectopic Pregnancy

Intrauterine devices (IUDs) are effective contraceptives but are also associated with a higher ectopic pregnancy risk than other contraceptive methods. This study assessed ectopic pregnancy risk with varying hormonal IUD dosages compared with copper IUDs.

We conducted a nationwide cohort study using data from the French National Healthcare Data System (SNDS) and identified first-time IUD dispensations from 2018 to 2022. The primary outcome was ectopic pregnancy occurrence within 1 year of the index date, set 1 month post IUD dispensing. We used propensity score-based weighting and Cox regression analysis to compare ectopic pregnancy risk among users of levonorgestrel 13.5-mg, 19.5-mg, and 52-mg IUDs versus copper IUDs.

Between 2018 and 2022, 45,450 women received a levonorgestrel 13.5-mg IUD, 212,301 received a levonorgestrel 19.5-mg IUD, 244,871 received a levonorgestrel 52-mg IUD, and 1,033,505 received a copper IUD. The mean age (standard deviation) was 26.8 (7.8), 29.7 (8.1), and 35.2 (8.2) years among levonorgestrel 13.5-mg, 19.5-mg, and 52-mg IUD users, respectively, and 29.1 (6.9) years in copper IUD users. At 1 year, ectopic pregnancy occurred in 71 levonorgestrel 13.5-mg IUD users (incidence rate, 0.18 per 100 person-years; 95% confidence interval [CI], 0.14 to 0.23), 182 levonorgestrel 19.5-mg IUD users (incidence rate, 0.10 per 100 person-years; 95% CI, 0.08 to 0.11), 88 levonorgestrel 52-mg users (incidence rate, 0.04 per 100 person-years; 95% CI, 0.03 to 0.05), and 682 copper IUD users (incidence rate, 0.07 per 100 person-years; 95% CI, 0.07 to 0.08). Compared with copper IUD users, the hazard ratios for ectopic pregnancy with hormonal IUDs were 2.57 (95% CI, 1.92 to 3.43) for 13.5-mg users, 1.37 (95% CI, 1.15 to 1.62) for 19.5-mg users, and 0.62 (95% CI, 0.49 to 0.80) for 52-mg users.

In this nationwide cohort study comparing three doses of hormonal IUDs and copper IUDs, the highest dose (levonorgestrel 52 mg) was associated with the lowest risk of ectopic pregnancy within 1 year compared with copper IUDs, whereas the 13.5-mg hormonal IUD was associated with the highest risk. (Funded by the French National Fund for Health Insurance and the French National Agency for Medicines and Health Products Safety.).