How Birth Control Methods Prevent Pregnancy

Hormonal

• Prevents ovulation.
• Thickens mucus at the cervix so sperm can't pass through.
• Changes the environment of the uterus and fallopian tubes to prevent fertilization and to prevent implantation if fertilization occurs.

Intrauterine device (IUD)

• There are two types of IUDs (hormonal and copper). Both types may work by preventing:
  • Fertilization of the egg.
  • Implantation in the uterus.

Barrier methods

• Block sperm from reaching the egg.
• Some are used with spermicide, which kills sperm.

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: Vasectomy blocks the release of sperm.
• Women: Tubal ligation surgery or tubal implants block the movement of an egg through the fallopian tube and prevent fertilization.