Hormonal preparations for contraception (hormonal contraceptives) contain sex hormones which act in a similar way to the estrogens and progesterone produced by the body.

They contain either a combination of estrogen and progestin (combined oral contraceptive, COC) or only a progestin (progestin-only pill, POP).

Progestin

It is the progestin component of the hormonal contraceptives that prevents conception. The action of the synthetic progestins is essentially the same as that of the progesterone produced by the body. Like progesterone, progestins suppress the activity of the hypothalamic-pituitary system. This stops ovulation from taking place. At the same time, progestins suppress the growth of the uterine lining so that implantation of an egg cannot take place. Progestins also make the mucus in the cervix thick and sticky which stops sperm from getting through.

Some synthetic progestins have additional positive effects apart from their contraceptive action.

For example, the progestin drospirenone counteracts the estrogen-induced accumulation of fluid in the tissues and can thus prevent breast tenderness or weight gain.

The progestins drospirenone, cyproterone acetate and dienogest also have anti-androgenic action and can thus be used for the treatment of androgen-related conditions such as acne.

Synthetic progestins are also suitable for use as long-acting preparations (e.g. in an intrauterine system, implant or in the form of the three-month injection).

Östrogen

Although it is the progestin that has the actual contraceptive action, combined oral contraceptives also contain a synthetic estrogen. As in the natural menstrual cycle the actions of the estrogen and the progestin complement each other with the aim of ensuring a regular cycle.

This is achieved particularly well by the combined oral contraceptive. After taking the COC for 21 days, bleeding occurs in the subsequent 7-day tablet-free interval.

With other combined preparations (e.g. the once-a-month injection) control of the menstrual cycle is not quite as reliable and irregular bleeding is slightly more common.

The most commonly used estrogen in hormonal contraceptives is ethinyl estradiol.