Mother-to-child transmission of HIV-1 in the era prior to the availability of combination antiretroviral therapy: the role of drugs of abuse.

Since the use of combination antiretroviral therapy (HAART) to treat pregnant women, the rate of mother-to-child transmission (MTCT) of HIV in the United States has dropped dramatically to less than 2%. With this, the principal determinants of the risk of transmission are the maternal viral load and her use of antiretroviral therapy (ART). However, in the pre-HAART era, the MTCT ranged from 12 to 45% and was influenced by a variety of risk factors for transmission including no ART during pregnancy or delivery, advanced maternal HIV infection (high viral load, low CD4 count, and AIDS diagnosis), prolonged rupture of membranes, first-born of twins, prematurity/low birth weight, chorioamnionitis, vaginal delivery or non-elective Cesarean section, and maternal drug use. Several studies in the pre-HAART era found maternal illicit drug use to be an independent predictor of MTCT. Reasons for this association may be both behavioral and biological. Drug use is associated with poor adherence to ART and medical care. Opioids enhance infection of macrophages by HIV.