A leading group of U.S. doctors said that, other than abstinence, hormonal implants or intrauterine devices (IUDs) are the most effective birth control methods for teenage girls, Time reports.

An IUD is a small, T-shaped piece of copper or hormone-treated plastic that’s inserted into the uterus and can prevent pregnancy for five to 10 years. An implant is a small plastic rod placed under the skin of the arm; it releases hormones that typically prevent pregnancy for three years. Both devices can be removed at any time without lasting effects on a woman’s fertility.

Recent studies show that women who use IUDs are up to 20 times less likely to have an unplanned pregnancy than women who use birth control pills, contraceptive patches or rings. Still, IUDs and implants aren’t as commonly used in the United States despite widespread acknowledgement of their effectiveness.

New guidelines from the American Academy of Pediatrics said pediatricians should suggest sexually active adolescents use the following contraception methods, in order of effectiveness: progestin implants, IUDs, injectable contraceptives and birth control pills.

According to doctors, birth control pills are the least effective contraceptive option because teenagers don’t properly and consistently take them. What’s more, when women use condoms, about 18 percent accidentally become pregnant. The rate of unintended pregnancy is much less for those who use copper IUDs.

For more information on how to find the birth control method that’s right for you, click here.