These guidelines replace CDC's 1995 guidelines, U.S. Public Health Service Recommendations for Human Immunodeficiency Virus Counseling and Voluntary Testing for Pregnant Women, and are for public- and private-sector service providers who provide health care for pregnant women. In 1998, the Institute of Medicine (IOM) published a report that recommended simple, routine, and voluntary human immunodeficiency virus (HIV) testing for all pregnant women in antenatal settings, given the effective interventions available to treat HIV-infected women and reduce risk for perinatal HIV transmission. In 1999, CDC convened consultation groups to discuss and comment on the IOM report. These guidelines are based on input from these meetings, the IOM report, and public comment on draft guidelines published in Fall 2000 in the Federal Register. These guidelines were also prompted by scientific and programmatic advances in the prevention of perinatally acquired HIV and care of HIV-infected women. These recommendations are consistent with the Revised Guidelines for HIV Counseling, Testing, and Referral. Major revisions from the 1995 guidelines include: emphasizing HIV testing as a routine part of prenatal care and strengthening the recommendation that all pregnant women be tested for HIV; recommending simplification of the testing process so that pretest counseling is not a barrier to testing; making the consent process more flexible to allow for various types of informed consent; recommending that providers explore and address reasons for refusal of testing; and emphasizing HIV testing and treatment at the time of labor and delivery for women who have not received prenatal testing and antiretroviral drugs. These guidelines recommend voluntary HIV testing to preserve a woman's right to participate in decisions regarding testing to ensure a provider-patient relationship conducive to optimal care for mothers and infants and to support a woman's right to refuse testing if she does not think it is in her best interest.