The number of children with AIDS continues to increase worldwide. Children who become infected with HIV-1 acquire the infection almost exclusively from their mothers during pregnancy or delivery, or via breast feeding. Mother-to-infant transmission has been, and continues to be, an area of active research with the goal being complete prevention. Treatment with zidovudine, an antiviral agent, has been found to decrease transmission from 25% to 8%. However, multiple obstacles impede the worldwide application of this advance.