A new study out of Washington University has found that long-term birth control methods are 20 times more effective at preventing unplanned pregnancies.

The research compared the rates of contraceptive failure in women using long-term methods like intrauterine devices or contraceptive implants to those using short-term methods like oral birth control pills or a contraceptive patch.

Wash U gynecologist Tessa Madden says the problem with options like the pill is that people can forget to take them.

“The real advantage of IUDs and implants is that they're forgettable,” Madden said. “And so once women start these methods they don't have to do anything on a day-to-day basis for the method to keep working.”

Madden says in the study, women under age 21 who relied on the pill or other short-term options were twice as likely as older women to have an unintended pregnancy.

She says even though IUDs and contraceptive implants are clearly more effective, most women in the U.S. still rely on birth control pills and condoms to prevent pregnancy.

She says one reason for that is price: IUDs and implants can cost up to $1,000.

“So if women don't have insurance, or they don't have contraceptive coverage through their insurance, that cost may be insurmountable,” Madden said.

But Madden says because IUDs and implants last for years, they actually end up costing less over the long term. And she says they can always be removed early if a woman decides she wants to get pregnant.

In the U.S. about half of all pregnancies are unplanned, accounting for 3 million pregnancies each year, the study says.

Send questions and comments about this story to feedback@stlpublicradio.org.