Natural versus synthetic estrogens in contraception and the risk of venous thromboembolism: an updated systematic review and meta-analysis
Introduction Combined oral contraceptives (COCs), composed of estrogen and progestin, have been widely used since the 1960s. Initially formulated with ethinyl estradiol (EE), efforts aimed to reduce venous thromboembolism (VTE) risk by lowering the EE dose, while in parallel new progestins were developed to improve tolerability [1]. Nevertheless, these newer progestins, once combined with EE […]