Late pregnancy screening for human immunodeficiency virus.

Three cases are presented of infants born to mothers who were screened and tested negative for HIV during their first trimesters. None of these pregnant women were retested late in their pregnancies, as they were not considered at high risk for HIV infection. All were found to be infected shortly after giving birth. Of the 3 infants, 2 developed HIV infection. These cases support a recommendation for late pregnancy HIV screening of all women.