The WHO estimates that during the first decade of the HIV/AIDS pandemic there were about 500,000 cases of AIDS in women and children, most of which have been unrecognised. During the 1990s, WHO estimates that the pandemic will kill an additional 3 million or more women and children world wide. HIV infection among heterosexual populations has been increasing throughout the world during the 1980s. AIDS has become the leading cause of death for women aged 20-40 in major cities in the Americas, Western Europe, and sub-Saharan Africa. In these cities, infant and child mortality could be as much as 30% greater than what would otherwise have been expected. During the 1990s, not only can hundreds of thousands of paediatric AIDS cases be expected, but also more than a million uninfected children will be orphaned because their HIV-infected mothers and fathers will have died from AIDS.