A new study has found that some men may be at greater risk of contracting the HIV virus when their female partner is pregnant, according to results presented today at the International Microbicides Conference at the David L. Lawrence Convention Center, Downtown.

Almost 1,000 participants from 47 countries are attending the meeting on HIV prevention research, continuing through Tuesday.

Also presented at the conference was a study that measured the safety of a woman's use of a microbicide during pregnancy.

It is believed that young women are at the greatest risk of acquiring the HIV virus, and that they may be even more vulnerable when pregnant.

Researchers from the University of Nairobi and the University of Washington reported today that, out of a group of 3,321 couples in which one partner was HIV-infected and the other was not, it was found that there was an increased risk of female-to-male transmission of HIV during pregnancy.

The study was conducted in Botswana, Kenya, Rwanda, South Africa, Tanzania, Uganda and Zambia. The researchers concluded that there may be physiological and immunological changes that occur with pregnancy, but that more research is needed to confirm that.

Another study testing a vaginal microbicide (the tenofovir gel) in healthy pregnant women found small amounts of the drug in the bloodstream, amniotic fluid and umbilical cord blood. These were lower amounts, the study found, than when the antiretroviral ingredient in the gel is given orally, a standard HIV treatment.

In this study, the gel was administered just two hours before a scheduled cesarean delivery for 16 women at Magee-Womens Hospital of UPMC.

The study is considered a first step toward determining if the gel is safe for women and their babies, according to study leader, Richard Beigi, of the University of Pittsburgh and Magee-Womens Hospital of UPMC, who led the study for the Microbicide Trials Network.

Women in clinical trials were previously told to stop using a product being studied if they became pregnant. But many women remain sexually active and condoms are not always used correctly, if at all. As an option, microbicides are being investigated as a method for women to protect themselves from HIV.

Also at the conference, researchers reported that there is growing scientific activity toward developing a safe and effective rectal-specific microbicide that will protect against HIV during anal sex.