contraception

The contraception - The control of fertility to prevent pregnancy. Contraception can be achieved by a variety of methods. Some forms prevent ovulation in the woman; others stop sperm from meeting an ovum in the fallopian tube (preventing fertilization), or prevent a fertilized ovum from implanting in the uterus.

Some contraceptive methods involve changes in sexual activity; such methods include total or periodic abstinence from intercourse (see contraception, natural methods of) and coitus interruptus, in which sexual intercourse is stopped before ejaculation occurs. Other methods, known as barrier methods (see contraception, barrier methods of), in volvethe use of condoms to prevent sperm from coming into contact with eggs.

Hormonal methods, including the use of oral contraceptives, implants, and injections (see contraceptives, injectable), prevent conception by altering the hormone balance in a woman’s body. Further forms of contraception include the use of intrauterine devices (see IUDs); postcoital methods (see contraception, emergency); or sterilization of the male (see vasectomy) or female (see sterilization, female).