Hormonal Contraception

Hormonal contraception refers to reversible methods that use hormones to prevent pregnancy. Most hormonal contraceptives contain a progestin, a compound with progesterone-like activity, either alone or combined with an estrogen. They are available in several forms, including pills, skin patches, vaginal rings, injections, subdermal implants, and levonorgestrel-releasing intrauterine devices .^1,2

The mechanisms depend on the specific method. Combined estrogen-progestin methods primarily prevent ovulation by suppressing hormonal signals from the hypothalamus and pituitary that normally stimulate ovarian follicle development and trigger ovulation. Progestin-only methods can also thicken cervical mucus, making it more difficult for sperm to pass through the cervix, and some suppress ovulation more consistently than others. Levonorgestrel-releasing intrauterine devices act mainly through local progestin effects, particularly thickening cervical mucus, and do not consistently suppress ovulation .^2,3

Hormonal contraceptives are commonly divided into combined and progestin-only methods. Combined hormonal contraceptives contain both an estrogen and a progestin and include combined pills, patches, and vaginal rings. Progestin-only methods include certain pills, implants, injections, and hormonal intrauterine devices. Because their hormone composition, dose, and route of delivery differ, these methods do not all produce identical physiological effects .^1,2

Hormonal contraception is a subset of contraception rather than a synonym for it. Nonhormonal methods, such as condoms and copper intrauterine devices, prevent pregnancy without administering contraceptive hormones .^1,3