Quantitation of human immunodeficiency virus type 1 during pregnancy: Relationship of viral titer to mother-to-child transmission and stability of viral load

Barbara Weiser, Sharon Nachman, Pamela Tropper, Kelly Hawkins Viscosi, Roger Grimson, Geraldine Baxter, Guowei Fang, Christine Reyelt, Nancy Hutcheon, Harold Burger

Research output: Contribution to journalArticle

95 Scopus citations


To develop strategies to prevent mother-to-child transmission of human immunodeficiency virus type 1 (HIV-1), it is important to define the factors determining it. We examined the relationship between maternal HIV-1 titer and the occurrence of mother-to-child transmission. In addition, we quantitated HIV-1 longitudinally in mother during pregnancy, at delivery, and up to 1 year postpartum. To examine transmission, we prospectively studied 19 mother- child pairs; in 5 pairs, HIV-1 transmission occurred. We used endpoint dilution culture of peripheral blood mononuclear cells to determine maternal viral titer and found that although 4 of 6 (67%) women with viral titers of ≥125 HIV-1 infectious units per 106 cells transmitted HIV-1 to their infants, only 1 of 13 (7.6%) women with lower viral titer transmitted (P = 0.01). Twelve of the 19 mothers had HIV-1 loads determined serially 3-8 times over periods ranging from 18 to 65 weeks. Viral titers varied greatly between the 12 women but the viral load in each woman remained stable over time. In this cohort, HIV-1 viral load remained stable during pregnancy and the greater the maternal viral burden, the more likely that transmission occurred. These two related findings suggest that determination of HIV-1 titers early in pregnancy may predict which women are at high risk of transmitting to their infants and may be used to counsel HIV-1-infected women of childbearing age. These data identify maternal viral titer as a major determinant of mother-to-child HIV-1 transmission and thereby provide the scientific rationale for therapeutic strategies designed to interrupt transmission by lowering viral load.

Original languageEnglish (US)
Pages (from-to)8037-8041
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number17
StatePublished - Aug 16 1994
Externally publishedYes



  • perinatal infection
  • vertical transmission

ASJC Scopus subject areas

  • Genetics
  • General

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