WASHINGTON, Nov 9, 2012 (AFP) - Twenty percent of young people born with HIV in the United States don't know they're infected when they have sex for the first time, according to a new study released Friday.

The study, which appeared in the Clinical Infectious Diseases journal, also found that most of the juveniles who were aware of their status said they did not tell their partners before becoming intimate.

In addition, a majority of these sexually active HIV-positive youth reported some sex without condom use.

"Our findings show that these young people act very much like their HIV-negative counterparts across the country," said Rohan Hazra of the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

"However, because of their HIV status, it is extremely important for health care providers, school counselors and family members to reinforce the importance of practicing safe sex, taking medication regularly and disclosing HIV status to potential partners."

The study consisted of 330 HIV-positive 10- to 18-year-olds who were given computer-guided questionnaires. It is being billed as the first to comprehensively examine factors linked to the initiation of sexual activity among young people born with HIV.

Nearly 10,000 people in the United States are living with HIV they got at or before birth, according to the Centers for Disease Control and Prevention.

On average, participants of the study who had initiated sexual activity reported having their first sexual experience at the age of 14. A third indicated that they had been honest about their HIV status with their first partner.

According to the study, 62 percent of those who were sexually active said they had sex at least once without the use of a condom. It also found that youngsters who did not take anti-HIV drugs on a regular basis were more likely to initiate sex than those who did so as prescribed.