Topic Overview

Birth control (contraception) is used to prevent unwanted pregnancy. Birth control methods work either by preventing the ovary from releasing the female egg (ovum) or by preventing the male sperm from fertilizing the ovum.

Most women are able to become pregnant from the time their menstrual periods begin (puberty) until their periods stop (menopause). This means that a woman could become pregnant any time from about age 12 to sometime in her 40s or 50s. This time period may be called a woman's reproductive years or her childbearing years. Birth control methods allow a woman or a couple to choose if and when to have a child.

How pregnancy (conception) occurs  

A woman in her reproductive years who is fertile has an 85% chance of becoming pregnant if she is sexually active and doesn't use birth control (85 out of 100 women who are sexually active and don't use birth control will be pregnant within 1 year). If a woman does not want to become pregnant, she has choices: Avoid sexual intercourse (abstinence) or use birth control.

Choosing a birth control method that works best for you depends on your medical history and your personal preferences. Important factors to consider include:

• The reliability of the method. Consider how important it is to you to avoid pregnancy, and then look at how well the method works to prevent an unwanted pregnancy (effectiveness).
• Your concern for getting a sexually transmitted disease (STD). To avoid an STD, including infection with the human immunodeficiency virus (HIV) that causes AIDS, you can abstain from sex, use male condoms, or be in a single-partner (monogamous) relationship with your partner who does not have STDs.
• Your medical history. You may have special needs to consider if you have a medical condition or a disability.

Sexually active teenagers need counseling on which birth control methods are appropriate for their age and their ability to use the method consistently.