Which factor places a prenatal client in the high-risk category for contracting HIV?

A history of intravenous drug use is a significant factor that places a prenatal client in the high-risk category for contracting HIV. This is due to the potential for sharing needles or other drug paraphernalia, which can introduce the virus directly into the bloodstream. Individuals who engage in intravenous drug use are at an increased risk for acquiring HIV, especially if they share injection equipment with others who may be HIV positive.

While unprotected sexual activity, having multiple sexual partners, and having no previous pregnancies can also impact a person's risk for HIV, the history of intravenous drug use is particularly critical because of the direct and efficient route of virus transmission associated with needle sharing. This risk factor highlights the importance of screening and preventive measures for pregnant women with such a history to ensure their health and the health of their unborn child.