Some methods of birth control are combined hormonal contraception which means they contain both estrogen and progesterone. The way the combined hormones work is by preventing ovulation. If a person does not release an egg, they cannot get pregnant.
Examples of combined hormonal birth control methods include the birth control pill, the contraceptive patch and the vaginal ring.
Some hormonal methods contain only one hormone called progesterone. This type of contraception is often referred to as progesterone only hormonal contraception.
The way that progesterone only contraception works is that progesterone thickens the cervical mucus to help prevent sperm from getting into the uterus, changing the lining of the uterus which helps prevent a fertilized egg (embryo) from implanting, and it changes the movement of the ovum (egg) inside the fallopian tube to help prevent the egg and sperm from meeting. Progesterone only contraception may or may not prevent ovulation.
Examples of progesterone only contraception include Depo-Provera injections (“the shot”), progesterone only pills (“mini pill”), hormonal IUDs such as Mirena s or Kyleena. Hormonal IUDs are also called Intrauterine Systems or IUS or Intrauterine contraceptives.