Most women keep using IUDs, contraceptive implants

More than 90 percent of women who opt for long-term reversible forms of birth control keep using them for at least six months, a new study found.

Those birth control methods include intrauterine devices (IUDs) and contraceptive implants.

The findings mean most women did not have side effects, such as cramping or bleeding, that were serious enough for them to stop using their birth control.

"There is the perception among healthcare providers that women discontinue these methods rapidly," senior author Dr. Tessa Madden said. She is an assistant professor of obstetrics and gynecology at the Washington University School of Medicine in St. Louis.

IUDs are placed inside the uterus and prevent pregnancy for up to five or 10 years, depending on the brand. The contraceptive implant is inserted under the skin of a woman's arm and works for three years.

Both methods are 99 percent effective at preventing pregnancy - better than the Pill, the vaginal ring and condoms. But they are used by less than one in ten U.S. women.

The IUD at a Glance Small, "T-shaped" device inserted into the uterus to prevent pregnancy Safe, effective, and long lasting Must be inserted by a health care provider Costs between $500 and $1,000 up front, but lasts up to 12 years

That is partly because some doctors may assume women will not be happy with these methods, the researchers said.

"We hope that this study helps reassure providers that the discontinuation rate is not a big concern," Madden said.

Her team's study included about 6,000 women between the ages of 14 and 45. Women could choose to start using the levonorgestrel-releasing IUD (marketed as Mirena), the copper IUD (ParaGard) or the contraceptive implant (Implanon).

How Does an IUD Work?

Both the copper and hormonal IUDs work mainly by affecting the way sperm move so they can't join with an egg. If sperm cannot join with an egg, pregnancy cannot happen.

For some women, hormonal IUDs may prevent the egg from leaving the ovary. Pregnancy cannot happen if there is no egg to join with sperm. Progestin also prevents pregnancy by thickening a woman's cervical mucus. The mucus blocks sperm and keeps it from joining with an egg.

The researchers counseled women about what to expect with their chosen birth control method. Then they kept track of if, when and why women stopped using their birth control through phone calls.

About seven percent of women using levonorgestrel IUDs or implants and eight percent of copper IUD users chose to have their device removed in the first six months. Younger women continued using these methods just as often as older women did, according to findings published in the journal Obstetrics and Gynecology.