THURSDAY, Jan. 19, 2012 (HealthDay News) -- Slightly more than half of U.S. teenaged girls who had a child between 2004 and 2008 did not use birth control, and a third didn't think they could get pregnant at the time, a new government study finds.
Although the number of teens who get pregnant in the United States has fallen in recent years, the U.S. teen birth rate is still the highest of any developed country, with more than 400,000 births in 2009, according to the U.S. Centers for Disease Control and Prevention.
"These are the girls who had risky sex and ended up getting pregnant and giving birth," said study co-author Lorrie Gavin, a health scientist with the CDC's Division of Reproductive Health. "This is the group that we should pay most attention to, because they're the ones who experienced unintended births."
According to the report, 50.1 percent of girls aged 15 to 19 who had an unintended pregnancy were not using any form of contraception when they got pregnant, and 31.4 percent thought they could not get pregnant at the time.
Commenting on the findings, Lawrence Finer, director of domestic research at the Guttmacher Institute in New York City, had this to say: "The fact that they found such a low level of contraceptive use says a number of things about what we need to do to try to improve adolescent reproductive health."
Finer said more teens should be using IUDs and implants because they take the decision-making out of the equation.
"In the past, these methods have been seen as ones for older women, but those methods should be considered first-line methods for adolescents and young adults," Finer suggested. "Historically, it's been condom and pill for young people, but we need to expand our thinking on that."
The girls who didn't think they could get pregnant have misconceptions about pregnancy, Finer added. "That clearly reflects on education and awareness," he said.
The reason some girls think that they can't get pregnant is probably a combination of factors, Finer explained.
"The risk of becoming pregnant from one act of sex is relatively small," he noted. "It may be the case that, for some teens, they had unprotected sex and didn't become pregnant so then they think they won't become pregnant based on their past experience," he said.
"This is a lack of recognition that if you don't get pregnant one time you may get pregnant at another time," Finer pointed out. In addition, some girls may think that either they or their partner is infertile.
Finer said more education about pregnancy and contraception is needed.
Another co-author of report pointed out other scenarios that might explain why these teens did not use contraception.
"Other reasons for not using contraception were their partner did not want to use it, or because they didn't mind getting pregnant," said Ayanna T. Harrison, who is also with the Division of Reproductive Health.
Among teens who got pregnant despite saying they used birth control, 24 percent said they used condoms and 21 percent said they used an IUD, implant or a birth control pill, said Harrison.
"When we looked at age, race and ethnicity, we didn't see a huge difference," Harrison said. However, among those who thought they couldn't get pregnant, 42 percent were Hispanic compared to almost 27 percent of white teens and 32 percent of black teens, she said.
Gavin added that most were not using the most effective methods of birth control, such as IUDs.
"They were using methods that require some kind of ongoing behavior, such as taking a pill every day or using a condom every time you have sex," she said. "We know that consistent use of the pill or a condom is a major problem."
Efforts are needed to dispel myths about becoming pregnant and to increase motivation to avoid pregnancy, Gavin said.
"We need to do a better job for sexually active teens," Gavin said, including providing better access to contraception, encouraging the use of more effective methods and increasing the motivation to use birth control consistently.
"Teen pregnancy is a public health concern because teen mothers are more likely to experience negative social outcomes, and infants of teen mothers have higher risks for preterm birth, low birth weight and related complications," the authors wrote.
The report was published in the Jan. 20 issue of the CDC's Morbidity and Mortality Weekly Report.
For more on teen pregnancy, visit the U.S. Centers for Disease Control and Prevention.