As our perspective of AIDS changes from a disease that affects homosexual men and intravenous drug abusers to one that spreads increasingly through heterosexual contact, greater numbers of women are being diagnosed with HIV infection. Because clinicians still may perceive AIDS to be primarily a "male" disease and may maintain a low level of suspicion of it in their female patients, HIV infection is believed to be underdiagnosed and go unrecognized for longer periods in women than in men. Early reports in the 1980s that showed a worse prognosis and shorter median survival for women than for men are now explained by factors such as later presentation and diagnosis, disparity in access to care, and reluctance of clinicians to prescribe zidovudine to pregnant patients. Recent studies show that, with early identification of infection and subsequent treatment and prophylactic therapy, there are no differences in disease progression or survival in women compared with men. Moreover, from a public health standpoint, earlier diagnosis can decrease incidence of both sexual and vertical transmission. Women may choose to undergo tubal ligation to prevent future vertical transmission; additionally, zidovudine now is used in pregnant women and has been demonstrated to decrease transmission rates from 25% to 8%