About 60 per cent of teen girls who have sex use the most effective kinds of contraception, including the pill and patch.
That's up from the mid-90s, when less than half were using the best kinds, the Centers for Disease Control and Prevention study found.
The trend in better contraception is helping to drive down the teen birth rate, health officials said.
The CDC released the report Thursday. It's based on a national survey of 2,300 girls ages 15 to 19, conducted in the years 2006 through 2010.
The most effective forms of birth control include the pill, patch, vaginal ring, IUD, the Implanon arm implant and the Depo-Provera contraceptive shot. Using only condoms was deemed just moderately effective.
Why are more teen girls now using hormonal birth control like the pill? Doctors seem to be increasingly comfortable prescribing them to teens, said Crystal Tyler, a CDC epidemiologist who co-authored the new report.
Also, some of them — like the vaginal ring — became available more recently, she said.
The teen birth rate fell 44 per cent between 1990 and 2010. Another factor besides better birth control is increasing abstinence. About 43 per cent of the girls in the survey said they'd had sex, the new study found. That's down from a similar survey in 1995, when 51 per cent of teen girls said they'd had sex.
"We hear a lot of times from teens that 'Everyone's having sex.' But a lot are not," Tyler said.
CDC report: http://www.cdc.gov/mmwr