A CDC study finds that while the teen birth rate in the U.S. is declining, it is still quite high, underscoring the need for more formal sex education.

Births to teens aged 15 to 17 years old have dropped, but they still account for over a quarter of teen births, or nearly 1,700 births a week, according to the Centers for Disease Control’s (CDC) Vital Signs. Now, a new CDC report states that these statistics underscore the need for targeted interventions to prevent teen pregnancy.

Tom Frieden, M.D., M.P.H., CDC director, said in the CDC’s press statement that although significant progress has been made in reducing teen pregnancy, far too many teens are still having babies.

“Births to younger teens pose the greatest risk of poor medical, social, and economic outcomes. Efforts to prevent teen childbearing need to focus on evidence-based approaches to delaying sexual activity and increasing use of the most effective methods of contraception for those teens who are sexually active,” said Frieden.

Analyzing birth data from the National Vital Statistics System and adolescent health behavior data from the National Survey of Family Growth, CDC researchers found that the rate of births per 1,000 teens aged 15 to 17 years old declined 63 percent, from 38.6 in 1991 to 14.1 in 2012.

Related News: Teen Mom Reality Shows May Decrease Teen Pregnancy »

The birth rate to younger teens is higher for Hispanic, non-Hispanic black, and American Indian/Alaska Native teens, according to the report. In fact, in 2012, the birth rate per 1,000 teens aged 15 to 17-years-old was 25.5 for Hispanic teens, 21.9 for non-Hispanic black teens, 17 for American Indian/Alaska Native teens, 8.4 for non-Hispanic white teens, and 4.1 for Asian/Pacific Islander teens.

CDC researchers also report that 73 percent of teens aged 15 to 17 had not had sex yet. What’s more, almost one in four teens in this age group never spoke with their parents or guardians about sex.

Watch: A Woman’s Guide to Safe Sex »

Among sexually active teens in this age group, the researchers found that before their first sexual experience, more that 80 percent had not received any formal sex education. Although more than 90 percent of teens used some form of contraception the last time they had sex, most of them used methods that are among the least effective, according to the CDC report.

Shanna Cox, M.S.P.H., at CDC’s Division of Reproductive Health, said in the agency’s press release, “We need to provide young people with the support and opportunities they need to empower themselves. Trying to balance the task of childbearing while trying to complete their high school education is a difficult set of circumstances, even with the help of family and others.”

Finally, Cox pointed out that teens who give birth are at increased risk of having a repeat birth while they are still in their teen years. They are also less likely to earn a high school diploma or GED than older teens who give birth, said Cox.

The Vital Signs report also underscores findings from previous CDC reports on teen pregnancy prevention, including the fact that racial and ethnic disparities in teen pregnancy rates remain. The report suggests that there is still a need for culturally appropriate interventions and services.

Learn More About Teenage Pregnancy »