Women who choose IUDs for long-acting reversible contraception (LARC) tend to keep the devices over several years, suggesting they’re satisfied with that method, according to a new U.S. study.

Women in the St. Louis, Missouri area who chose long-acting methods like an intrauterine device (IUD) or an implant that's placed under the skin were more likely to still be using it three years later than women who opted for shorter-acting methods like the pill, patch or vaginal ring, researchers found.

“At 24 months we saw that about 75 percent of women using LARCs continued their baseline contraceptive,” said lead author Dr. Justin Diedrich of Washington University. “At 36 months two-thirds continued. These results are very reassuring - they show us that women using the most effective methods of birth control continue at high rates.”

“Because they work so well, the LARC methods should be the first option considered,” Diedrich told Reuters Health by email.

For the new study, the researchers looked at data from the Contraceptive CHOICE Project, which involved women ages 14 to 45 who were sexually active with a male partner and interested in starting a new method of reversible contraception.

After initial counseling on the long- and short-acting reversible contraception options, the women were tested for sexually transmitted infections and were given their birth control method of choice free of charge.

Once placed by a doctor, the hormonal IUD (Mirena) and copper IUD (Paragard) can remain effective for many years. The Implanon rod is inserted under the skin of the arm and can last up to three years.

Shorter-term options included the depot medroxyprogesterone acetate shot (Depo Provera), which is a hormonal injection given by a health provider every three months, or daily birth control pills, the contraceptive patch or the vaginal ring (Nuva Ring).

The patch should be reapplied three times per month and the ring should be replaced once per month.

The researchers followed 4,708 women with telephone surveys every six months for three years, including 3,203 who had chosen long-acting contraception.

Women who decided to stop using contraception because they wanted to get pregnant were not included in the study.

At the three-year mark, almost 70 percent of women who had chosen the hormonal or copper IUD were still using it, and 56 percent of those with a subdermal implant still had it. Overall, about 30 percent of those who had chosen short-term methods were still using them, as reported in the American Journal of Obstetrics and Gynecology.

Women who had chosen long-acting contraception tended to be older, were more likely to have public insurance and more often had a history of unintended pregnancy.

Women appear to be happy with LARC methods and continue them significantly longer than non-LARC methods, Diedrich said.

An IUD can cost more than $1,000, compared to between $10 and $30 for a one-month pack of birth control pills, Diedrich said.

Some women without insurance are unable to pay for a LARC, some insurers affiliated with religious organizations do not cover contraceptives and others charge a co-pay, all of which makes it harder for women to get the long-acting contraception they would prefer, he said.

“There may be a higher upfront cost for LARC methods, but they work much better, and people use them longer,” which ultimately makes them cost-effective, he said.

“This is creating more evidence to support the idea that women who are using IUDs and implants seem to be highly satisfied,” said Megan L. Kavanaugh, senior research scientist at the Guttmacher Institute in New York, who was not part of the study.

With the Affordable Care Act going into effect, more and more women should have access to these more expensive options, Kavanaugh said.

Still, there is no one best option for everyone, Kavanaugh told Reuters Health.

“We want a diversity of options,” she said. “What’s right for (a woman) when she’s 17 may not be the same when she’s 27 or 37.”

More than 90 percent of unintended pregnancies in the U.S. are due to contraceptive nonuse or misuse, and LARCs remove that risk, Kavanaugh noted.