As we noted earlier this year, Pittsburgh has been the hub of research into microbicides -- topical substances that prevent the sexual transmission of HIV when applied vaginally or rectally.

And in a recently launched clinical trial, researchers are foraying into another area that's relatively new: determining if such substances are safe for women who are pregnant or breastfeeding.

The study is being conducted by the Microbicide Trials Network (MTN), funded by the U.S. National Institutes of Health and based at the University of Pittsburgh and Magee Women's Hospital Research Institute.

Early studies of one microbicide -- called tenofovir gel -- found HIV transmission risk was reduced by 39 percent among women who used it before and after vaginal sex (the gel is also being reformulated and studied for use rectally). The new clinical trial will determine if tenofovir is safe for pregnant or lactating women to use.

"Preventing HIV during pregnancy and lactation is a majorly important time,"Dr. Richard Beigi tells City Paper. Beigi is the principle investigator of the trial, and is also an assistant professor of obstetrics, gynecology and reproductive sciences at the University of Pittsburgh School of Medicine. "Data suggests pregnant women may be more susceptible then non-pregnant women [to HIV]. Data also suggests if a woman gets a new [HIV] infection during pregnancy or while lactating, they are significantly more likely to pass that onto their baby."

As Beigi noted in an earlier press release from the MTN, the gel and other microbicides are intended to be used by sexually active women -- "the very women most likely to get pregnant, yet we have very little information about whether these products are safe for them to use."

In addition to Magee in Oakland, the trial is also being conducted at the University of Alabama in Birmingham. Beigi says about eight women are enrolled at Magee so far, and he hopes to have up to 90 pregnant women and 15 lactating women to participate.