MYTH: Women need a Pap smear when they turn 18

In 2003, the American College of Obstetricians and Gynecologists changed its recommendation for Pap tests, also known as Pap smears; previously, the test was recommended immediately after a woman first has sexual intercourse or at age 18, whichever came first.

Now, Pap tests aren't recommended until women have been sexually active for about three years, or until they turn 21.

An early Pap test may seem harmless, but the stress of needing a Pap—often thought of as an uncomfortable and invasive procedure—may cause young women to avoid their gynecologist or refrain from asking about birth control. Young women should be able to approach their doctors and discuss these issues without the scrutiny of unnecessary tests, says Dr. Yen.

Why the reason for the change? Most cases of human papillomavirus (HPV) clear up on their own within three years; it's only the cases that stick around longer—and will be picked up by a later Pap test—that are real causes for concern because they can lead to cervical cancer.