The objective of this study was to highlight the value of preventing unintended pregnancies among HIV-infected women as a strategy to prevent perinatal HIV transmission. The study assessed the cost-effectiveness of family planning programs to avert HIV-positive births with the current programmatic emphasis: prenatal care services that provide and promote nevirapine for prevention of mother-to-child transmission of HIV. Cost-effectiveness analyses were conducted from the health system perspective during 1 year with a hypothetical sub-Saharan African population. Expected program costs were combined with number of HIV-positive births averted for each strategy.