NEW YORK (Reuters Health) - Sexually active teenage girls infected around the time of birth with HIV, the virus that causes AIDS, are more likely to have cervical infections and abnormal Pap test results, new research shows.

Extensive research has examined the reproductive health outcomes among teenagers who acquire HIV infection through sex, senior investigator Dr. Susan B. Brogly of Harvard School of Public Health in Boston told Reuters.

In contrast, this is the largest cohort study, and the first to publish on rates of genital infections, cervical lesions, and pregnancy among girls who had been living with HIV since birth, she said.

Their results will be published in the June issue of the American Journal of Public Health.

The study involved a total of 638 girls infected with HIV during birth, and who were 13 to 21 years old when they entered a pediatric AIDS study between 2000 and 2005. Brogly and her co-investigators estimate that 174 of the girls were sexually active. More than three-quarters were receiving HIV medication.

Pelvic examinations revealed multiple cases of genital warts. Many of the HIV-infected teenage girls were found to have sexually transmitted diseases, including trichomoniasis, chlamydia, gonorrhea and syphilis.

Of the 101 sexually active girls who had Pap tests, 30 (29.7 percent) had abnormal results at the first examination including lesions that have the potential to become cancerous called squamous intraepithelial lesions or SIL.

"We were surprised at the high rates of SIL that were observed," Brogly said. "It is concerning to find such high rates in young adolescent girls."

She and her colleagues were also taken aback by the finding that "pap smears were so infrequent among these girls identified as sexually active."

Thirty-eight girls became pregnant for the first time while in the study. Seven were pregnant more than once, resulting in 32 pregnancies that ended with live births. Of these, only one newborn was known to be HIV-infected.

The rate of pregnancy is much lower in this cohort than among HIV-uninfected girls of similar ages in the US, the team reports. Brogly attributes the low pregnancy rates to the fact that "some of these girls have severely compromised health and serious illness, making it difficult to become pregnant."