The head of Denver's HIV prevention program said Wednesday he doesn't recall the last time an HIV-positive baby was born here.

Still, Dr. Mark Thrun, director of HIV prevention for Denver Public Health, said he believes all pregnant women should be tested for the disease because it's easy to stop its spread to a newborn.

"(Perinatal transmission cases) are few and far between," Thrun said. "But when they happen, they're tragic."

Thrun said he supports a legislative push to require all pregnant women to be tested for HIV. The state recommends that all pregnant women be tested, but that doesn't mean it happens at every medical facility.

"In some institutions, (HIV testing) is not required yet," he said. "Mothers will slip by that have not been tested. ... We are trying to bring all hospitals up to what's considered a standard of care."

Measures similar to what's being discussed in Colorado have resulted in one of the greatest success stories in HIV prevention, Thrun said.

A 2006 report by the Centers for Disease Control and Prevention found the number of children diagnosed with AIDS after being exposed to HIV at birth peaked at 945 in 1992. By 2004, only 48 such AIDS cases were reported nationwide.

The drop is attributed to the identification of HIV-infected pregnant women and the effectiveness of anti-retroviral drugs given to mothers and infants near the time of birth. Still, between 144 and 236 perinatal HIV infections are reported in the United States each year. Figures were not immediately available for Colorado.

Thrun disputed Republican Sen. Dave Schultheis' assertion that most pregnant women who are HIV-positive have become infected through sexual promiscuity.

"The majority of women diagnosed with HIV had only one sex partner in the last 12 months," he said.

Statewide, 488 women are living with AIDS. More than half - 269 - became ill after engaging in high-risk heterosexual sex. Of the 4,023 men with AIDS, 2,848 contracted it after sexual contact with other men.