Narrator: When teens use birth control, motivation makes a difference. This is Science Today. Dr. Philip Darney compared three different methods of birth control among 400 teenagers -- condoms, the pill, and Norplant, a contraceptive delivery system that's surgically implanted in the upper arm. Darney found that the teens who chose Norplant had a much lower pregnancy rate -- zero, in fact -- than the teens using the other two methods. He also found that Norplant users tended to be older and more sexually responsible. Many had already gone through an unwanted pregnancy.

Darney: We think we enrolled people who were highly motivated to avoid pregnancy, and they were willing to use this method that has a lot of bothersome side effects -- it's a very safe method but it has bothersome side effects like irregular bleeding, sometimes acne, weight gain -- things teenagers wouldn't like to have happen to them. 058 But they were so motivated to avoid, generally, another unplanned pregnancy that they wanted to use this method.

Narrator: Darney says family planners should consider Norplant when recommending birth control to teenagers. For Science Today, I'm Steve Tokar.