IUDs are the most effective contraceptive — and the top birth control choice among female women's health care providers, a new survey shows.

Forty-two percent of doctors say they use a long-acting reversible contraceptive (LARC) method like intrauterine devices (IUDs) and the contraceptive implant. Among the general population, numbers are much lower: separate survey data shows 12 percent of women chose the same option.

"The difference in contraceptive choices between providers and the general population is even higher than we expected," said Dr. Ashlesha Patel, lead researcher on the study, published Monday in the journal Contraception.

What the researchers found

Researchers surveyed 500 female women's health care providers between 25 and 44. They found that 67 percent were using contraception. Of those women, 42 percent were using a long-acting reversible contraceptive (LARC) method like intrauterine devices (IUDs) and the contraceptive implant.

The researchers asked the doctors what their biggest consideration was when choosing their birth control method, and half said effective pregnancy prevention.

And for pregnancy prevention, there isn't really a better option than IUDs. There's less room for human error with IUD than with a daily contraceptive like the pill. IUDs have less than a 1 percent failure rate, while birth control pills have about a 6 percent failure rate.

The new study backs up similar findings that medical providers prefer IUDs to other forms of birth control. A 2014 study published in Obstetrics and Gynecology found that 40 percent of female family planning providers between the ages of 19 and 44 used IUDs, while only about six percent of women in the general population were using an IUD or similar long-acting reversible contraceptive.

The IUD gap might be closing

There are some signs that the general public is gravitating towards long-acting contraceptives. IUDs are now the third most popular contraceptive choice among American women between the ages of 25 and 44, behind the pill and condoms. Planned Parenthood reports a 91 percent increase over the last five years in the use of IUDs and the birth control implant.

The uptake in IUD use could be, in part, due to a provision in the ACA that gave women with private insurance access to birth control without having to pay anything out-of-pocket. It's made LARCs more affordable and accessible for more women.

It's also true that female women's health care providers may be more likely to use LARCs because they're generally better informed about the effectiveness of contraceptives than the general public. A 2012 study published in Contraception found how much a woman knows about birth control is correlated to what type she'll choose – women who chose LARCs were more in the know than other contraceptive users about the efficacy of different methods.