Risk of Stroke in Women Using Levonorgestrel-Releasing Intrauterine Device for Contraception

Abstract

Background: The commonly used combined hormonal contraceptives with progestins and ethinylestradiol are associated with an increased risk of ischemic stroke (IS). Progestin-only preparations, including levonorgestrel-releasing intrauterine devices (LG-IUDs), are not associated with an increased risk, and in smaller studies, the risk is even reduced. The risk of intracerebral hemorrhage (ICH) has never been investigated. We studied the risk of IS and ICH in women using LG-IUDs compared with women not using hormonal contraceptives.

Methods: In this Danish historical cohort study (2004-2021), we followed nonpregnant women (18-49 years) registering incident IS and ICH in relation to use of LG-IUDs/nonuse of hormonal contraceptives utilizing Danish high-quality registries with nationwide coverage. Poisson regression models adjusting for age, ethnicity, education, calendar year, and medication use for risk factors were applied.

Results: A total of 1 681 611 nonpregnant women contributed 11 971 745 person-years (py) of observation. Mean age at inclusion was 30.0 years; mean length of follow-up was 7.1 years; 2916 women (24.4 per 100 000 py) had IS; 367 (3.1 per 100 000 py) had ICH. Of these, 364 784 were users of LG-IUD contributing 1 720 311 py to the investigation; mean age at start of usage was 34.6 years. Nonusers of hormonal contraceptives contributed 10 251 434 py; mean age at inclusion was 30.0 years. The incidence rate of IS/ICH among LG-IUD users was 19.2/3.0 and among nonusers, it was 25.2/3.1 per 100 000 py. After adjustment, incidence rate ratio for IS was 0.78 (CI, 0.70-0.88), and for ICH it was 0.94 (CI, 0.69-1.28).

Conclusions: The use of LG-IUD was associated with a 22% lower incidence rate of IS without raising the incidence rate of ICH. The finding raises the question of whether levonorgestrel, in addition to its contraceptive properties, could have the potential to prevent IS.

Keywords: cerebral hemorrhage; contraceptives; intrauterine devices; ischemic stroke; levonorgestrel.