Background

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.

Methods

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.

Results

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.

Conclusions

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.)