By Dr. Natasha Bhuyan

Long-acting birth control methods, such as the IUD and implant, could cut pregnancy rates by almost 80 percent in sexually active teens, according to a new study.

Researchers studied 1,404 teenagers who were offered free birth control of their choice. A majority chose a long-acting reversible contraception, such as IUD or implant. After three years, their pregnancy rate was 3.4 percent, compared with almost 16 percent in the general sexually active teen population.

The study appeared Wednesday in the New England Journal of Medicine.

"It was really exciting to see these outcomes," said Gina Secura, a lead author of the study and professor of epidemiology at Washington University in St. Louis. "We were thinking we would have reduction rates at less than 10 percent."

An IUD is a t-shaped device placed into the uterus, while the subdermal implant is a small rod placed under the skin. Both methods involve more interaction with doctors than other commonly used birth control methods, such as condoms. But they are effective for three to 10 years, depending on the specific device. Unlike condoms, however, devices like these offer no protection against sexually transmitted infections.

Secura said there are several reasons that more teens don't use IUDs or implants. In addition to their cost, she said, many providers don't stock the devices or require patients to return for additional visits before placing them.

The new study follows a recommendation by The American Academy of Pediatrics earlier this week urging doctors to encourage sexually active teens and adolescents to look to IUDs and implants as their first option.

Dr. Mary Ott, an adolescent medicine specialist at Indiana University and lead author of the American Academy of Pediatrics guidelines, said since teens often make errors when using other forms of birth control - such as neglecting to take birth control pills on time - these implants offer an edge when it comes to pregnancy protection.

"Teen pregnancy has both health risks and social costs," said Ott, who was not involved with the study. "Teens who become pregnant are less likely to finish high school, go to college… there are economic and educational costs."

Doctor's Take

There are more than 600,000 American teen pregnancies per year, according to the Guttmacher Institute. Given the costs - both to individual teens and to society - it is clear that there are big upsides to preventing these pregnancies. And research shows best ways to combat teen pregnancy include medically-accurate sexual health education and access to contraception.

Adolescents who are sexually active should talk to their doctors about the best birth control options for them. Federally supported Title X family planning clinics offer reproductive care at a reduced cost.

But another essential part of preventing teen pregnancy is for adolescents to have a parent or other trusted adult in whom they can confide to discuss values and healthy relationships.

And because long-acting methods do not prevent sexually transmitted infections, it is important that teens know that barrier methods are also an important part of safe sex.