Maternofetal transmission of AIDS: frequency of human immunodeficiency virus type 1 nucleic acid sequences in human fetal DNA.

Pediatric AIDS is increasing in frequency due to a rise in the number of human immunodeficiency virus type 1 (HIV-1)-infected women of childbearing age. Because outcome studies reveal that most children infected peripartum manifest HIV-1-related disease in the first year of life, intrauterine infection has been suspected. Fetal tissues from 23 second-trimester abortuses were examined. The presence of HIV-1 nucleic acid sequences was determined by the polymerase chain reaction and used to define infection of the fetus. By analysis of available tissues, 7 of 23 fetuses were infected, while control fetal tissue was negative. In situ hybridization for HIV-1 DNA showed that only 1 of 8 infected abortuses was positive, while all samples of noninfected tissues revealed no HIV-1 DNA. These studies indicate that maternofetal transmission of HIV-1 may occur in 30% of pregnancies (7/23) by the end of the second trimester.