A study carried out by the U.S. Centers for Disease Control and Prevention (CDC), shows that any type of sex education delays the beginning of sexual life in teenagers.

Earlier last month, a study lead by Douglas Kirby of the ETR Associates revealed that two thirds of 48 comprehensive sex education programs have had a good impact on teenagers. They delayed the initiation of sex, reduced its frequency and the number of sexual partners.

"Two-thirds of the 48 comprehensive programs that supported both abstinence and the use of condoms and contraceptives for sexually active teens had positive behavior effect," said the report.

On the other hand, other studies made in November as well, have said that these abstinence programs have little effect on the teenage sexual behavior, because, as the report discovered, 47 percent of high school students have engaged in sex at least once and 63 percent have said that they have sex during the spring semester of their senior year.

This time, researchers found that teenage boys who had sex education in school were 71 percent less likely to have intercourse before age 15 and girls who had formal sex education were 59 percent less likely to have sex before the age 15. The researchers also discovered that sex education reduced by 91 percent the risk that African-American females in school would have sex before age 15.

"Sex education seems to be working. It seems to be especially effective for populations that are usually at high risk," Trisha Mueller, an epidemiologist with the CDC who led the study, said.

Researchers used data from an older survey of the National Survey of Family Growth, in 2002, including answers from 2,019 teenagers between the ages of 15 and 19.

The conclusion of the study was that formal sex education also seems to lead to safer sex. Boys who had received sex education were three times more likely to use birth control the first time they had sex, but the case stayed different in the case of the girls.

"Unlike many previous studies, our results suggest that sex education before first sex protects youth from engaging in sexual intercourse at an early age," said researchers in the study.

The researchers did not consider the content of sex education programs, meaning whether students were taught about contraception or about abstinence only.