How Birth Control Methods Prevent Pregnancy

Reference Hormonal Opens New Window Reference Opens New Window

• Prevents Reference ovulation Opens New Window
• Thickens mucus at the Reference cervix Opens New Window so sperm cannot pass through
• Changes the environment of the uterus and Reference fallopian tubes Opens New Window to prevent fertilization and to prevent implantation if fertilization occurs

Reference Intrauterine device (IUD) Opens New Window Reference Opens New Window

• The progestin released by the hormonal IUD prevents fertilization by making the mucus in the cervix thick and sticky, so sperm can't get through to the Reference uterus Opens New Window. The progestin and IUD change the uterine lining, preventing implantation in the rare case that fertilization occurs.
• The copper in the copper IUD is toxic to sperm. It causes changes in the uterus and fallopian tubes that kill sperm. The IUD changes the uterine lining, which prevents implantation in the rare case that fertilization occurs.

Reference Barrier methods Opens New Window Reference Opens New Window

• Block sperm from reaching the egg
• Some are used with spermicides, which kill sperm.

Reference Fertility awareness (natural family planning)

• Identifies the time during a woman's cycle when she is most likely to become pregnant (fertile). An extra method or abstinence should be used during this time of fertility.

Permanent birth control (sterilization)

• Men: Reference Vasectomy Opens New Window blocks the release of sperm.
• Women: Reference Tubal ligation surgery or tubal implants Opens New Window block the movement of an egg through the fallopian tube, preventing fertilization.