While having fewer than 500 CD4 cells/mm3 is not a sign of advanced HIV disease, it does indicate a significant decline in the immune system's capabilities. (Many of the women likely had far fewer than 500 cells/mm3 at the time of childbirth.) Therefore, the authors said, disease stage at the time of childbirth is a strong factor in the overall odds of MTCT. Lead author Valeriane Leroy, MD, PhD, a