Hormonal IUDs.pdf

Intrauterine devices (IUDs) are a widely used, safe, and effective long-term reversible contraceptive method, with over 150 million women worldwide using them. The levonorgestrel-releasing intrauterine system (LNG-IUS) is a popular contraceptive that has gained popularity since its introduction in Europe in 1990 and the US in 2000. Despite its effectiveness, the mechanism of action of LNG-IUS is not entirely clear, with research constrained by a lack of ideal animal models and ethical considerations. The predominant mechanism of action is thought to be impairment of sperm transport through the cervix and uterus, with endometrial atrophy being a key feature of long-term LNG-IUS use. This atrophy may lead to a reduction in endometrial fluid, creating a "dry intrauterine swimming pool" that hinders sperm transport and function, potentially impairing fertilization and implantation. Further research is needed to fully understand the mechanism of action of LNG-IUS and its effects on sperm transport and endometrial changes.