"There is a strong relationship between poverty and early childbearing," he said.
Given the growing number of young people using more than one type of contraceptive -- as high as 30 percent in some groups -- analysts said there is evidence that teens are concerned about unwanted pregnancy and diseases spread through intercourse. When used correctly, condoms are highly effective at reducing the risk of AIDS, syphilis and gonorrhea.
"The messages have been toward protecting yourself against not only pregnancy but also STD [sexually transmitted disease] transmission," said Joyce Abma, lead author of the report. "There are many female methods that prevent against pregnancy but not STDs. Finally, the messages are being picked up and acted upon."
Every type of contraception, including the newer injectable methods and the high-dose "emergency" oral pill, was more widely used by teenagers in 2002 than before, the study found.
"The really good news is that kids are waiting. They are getting to maturity so they can make healthier choices," said Joneen Krauth-Mackenzie, executive director of the Denver-based Abstinence and Relationship Training Center. "Kids are seeing the cause and effect; they know they need to do something to reduce the risk."
The next step is to shift the focus from contraception to abstinence, she said. "When you engage in those kind of behaviors, you reduce your risk but you don't protect."
The survey did raise questions about where young people get information on reproductive health. One-third of teenagers said they did not learn about contraception in school, and only half of young women and one-third of young men said they had discussed birth control with a parent before turning 18.
"It's quite shocking how little information they're getting from adults," said Cynthia Dailard, senior public policy associate at the nonpartisan Alan Guttmacher Institute.