CHICAGO — Teenage girls who have sex should use IUDs or hormonal implants – long-acting birth control methods that are effective, safe and easy to use, the nation’s most influential pediatricians’ group recommends.

In an updated policy, the American Academy of Pediatrics says condoms also should be used every time teenagers have sex, to provide protection against sexually transmitted diseases that other forms of birth control don’t provide, and to boost chances of preventing pregnancy.

Condoms alone are the most common birth control choice among teenagers, but with typical use they’re among the least effective methods of preventing pregnancy.

Both long-acting methods are nearly 100 percent effective, with lower failure rates than birth control pills, patches and injections, the academy says.

IUDs and hormonal implants cost more, usually hundreds of dollars, because inserting them involves a medical procedure typically done in doctors’ offices. But they’re less expensive in the long run than over-the-counter condoms or prescription birth control pills, said Dr. Mary Ott, an adolescent medicine specialist and associate pediatrics professor at Indiana University, the policy statement’s lead author.

Teenagers have to remember to use pills and condoms consistently. By contrast, IUDs typically work for three to 10 years after insertion, while implants typically last three years.

The new guidance was published Monday in Pediatrics.