While Pap smears remain an essential part of cervical cancer prevention, new guidelines discourage the once-a-year screenings that have been a part of women's health for years.

New recommendations from the U.S. Preventive Services Task Force, which is part of the Department of Health and Human Services,  state that women who are 21 to 29 years old only need a Pap smear every three years. And those under the age of 21 do not need a Pap smear at all, regardless of  sexual history.

And healthy women age between the ages of 30 and 65 need a Pap smear only  every five years  if they combine it with a test for human papillomavirus, or HPV,  which can develop into cervical cancer.

The guidelines, published in the Annals of Internal Medicine, are in sync with those of the American Cancer Society and the American Society of Clinical Pathology. Previously, the medical groups  recommended Pap smears at least every three years.

But they've  found that testing every three years prevented just as many cervical cancer deaths as testing every year. But  the annual testing brought on false-positives, unnecessary biopsies, which bring a risk of infection, pregnancy complications and infertility, and, of course, unnecessary stress.

"The big point is that every woman needs to get screened," Dr. Richard Besser, chief health and medical editor at ABC News, said on "Good Morning America"  Thursday. "Almost half of women never get tested, and their cancers are picked up when they have symptoms.  But beyond that, read these guidelines, think about it and talk to your doctor about what type of screening and how frequently is right for you."

The Pap smear was first introduced in 1941,  and reduced deaths from cervical cancer,  which was once the No. 1 cancer killer among women, by about 70 percent, according to the American Cancer Society.

"Cervical cancer screening is a success story, but the more testing you do, the more you run the risk of false positives, and potential harm of over treatment," Dr. Wanda Nicholson, a task force member and associate professor of obstetrics and gynecology at University of North Carolina at Chapel Hill School of Medicine, told ABCNews.com last  October.

Nevertheless, women still need their annual pelvic and breast examinations.

"With all these different recommendations, we run the risk of having people to start missing their Paps and make it seem like they're not important enough," Dr. Jacques Moritz, director of gynecology at St. Luke's-Roosevelt in New York City,  said in October. "You still need your annual exam. That means, you need your breast and pelvic exam. You just don't need the actual swabbing of the cervix every year."