WEDNESDAY, May 23, 2012 (Health.com) — The small fraction of women who choose intrauterine devices (IUDs) or under-skin implants as their preferred method of birth control may be on to something: According to a new study, these long-acting forms of contraception are 20 times better at preventing unintended pregnancies than the Pill and other short-term methods.
The study, published this week in the New England Journal of Medicine, compared the effectiveness of various types of birth control in a group of about 7,500 sexually active women in the St. Louis area. Over a period of three years, 9.4% of women using birth control pills, patches, or vaginal rings became pregnant accidentally, compared to just 0.9% of women who opted for IUDs or implants.
The difference in these so-called contraceptive failure rates was especially dramatic among teenagers and young women, a group at high risk for unintended pregnancies. Women under age 21 who used short-term birth control were nearly twice as likely as their older counterparts to become pregnant, whereas the failure rate for IUDs and implants was less than 1% regardless of age.
“It’s not that birth control pills aren’t effective, because they are—when they’re used perfectly,” says Jeffery Peipert, M.D., a study author and professor of obstetrics and gynecology at Washington University Medical School, in St. Louis. “But humans aren’t perfect, and it’s normal to forget to take a pill every day or file for prescription refills every month.”
Birth control pills, the method of choice for 28% of U.S. women, are the most commonly used form of reversible contraception, but their effectiveness depends on consistent daily use. Nationally representative surveys have reported failure rates with the Pill similar to those seen in the current study.
Patches and rings require less attentiveness than pills, but they still leave room for human error. The birth control patch (known by its brand name, Ortho Evra) needs to be changed weekly, while the vaginal ring (known as NuvaRing) needs to be changed once a month.
By contrast, IUDs and implants are designed to be foolproof. An IUD, a T-shaped piece of plastic inserted into the uterus by a gynecologist, can remain in place for five to 10 years. Implants such as Implanon and Nexplanon, matchstick-size devices inserted below the skin on the upper arm that release a slow trickle of hormones, can last up to three years.
Despite being far more effective than pills, IUDs and implants—collectively known as long-acting reversible contraception (LARC)—have proven to be less popular with women. According to the latest government data, just 5.5% of women on birth control use IUDs and less than 1% use implants.
“When a woman tells her ob-gyn that she wants to go on birth control, most doctors offer the Pill right off the bat,” Peipert says. “That needs to change. If there were a drug for cancer that was 20 times more effective, we would obviously recommend that first—and that’s what we should be doing for contraception, as well.”
A third type of birth control, the hormone injections sold under the brand name Depo-Provera, had a low failure rate comparable to those of IUDs and implants, the study found. That rate may not accurately reflect the real-world effectiveness of the shots, however, since the study included only women who received them every three months, as required, Peipert says.
Next page: High upfront costs with IUDs