Of a new study presented at the 47th Interscience Conference on Antimicrobial Agents and Chemotherapy in Chicago (ICAAC) this week, AIDSmap reports that the percentage of pregnant women who tested positive at a Zimbabwe hospital dropped by 41 percent between 1999 and 2007.

In the study, researchers offered HIV testing to pregnant women at the Howard Hospital in rural northern Zimbabwe. Of the 15,555 women tested for HIV between August 1999 and August 2007, 3,121 tested positive. During the eight years of observation, HIV prevalence fell by an average 1.4 percent per month from a high of 26.6 percent to an estimated mean of 15.6 percent. During the same period, HIV prevalence in pregnant South African women remained stable around 30 percent.

Though the study was not designed to determine what caused the drop in prevalence, researchers stated that the contributing factors might have included local HIV-prevention programs in tandem with social changes that have occurred as a result of Zimbabwe’s economic troubles.