Higher in utero and perinatal HIV infection risk in girls than boys

Robert J. Biggar, Taha E. Taha, Donald R. Hoover, Francis Yellin, Newton Kumwenda, Robin Broadhead

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Objective: This study analyzed mother-to-child HIV transmission rates by sex and exposure time for babies born to HIV-infected, untreated African women. Methods: Data were analyzed from 2 independent studies done in Malawi during the 1990s. Infections were established by polymerase chain reaction on blood samples. Odds ratios (ORs) for transmission were examined by period at risk: in utero (infected in umbilical cord blood), perinatal (infected in 1st postnatal blood ≥4 weeks), and postnatal (later postnatal infection). Results: Among 1394 singleton births, girls were more likely to become infected than boys. For in utero transmission, the OR was 1.4 (95% CI: 0.9 to 2.2). For transmission during early life (umbilical cord blood not available) the OR was 2.7 (95% CI: 1.5 to 4.9). However, transmission risks in the perinatal and postnatal infection periods did not differ in boys and girls. Among 303 tested twin-birth pairs, girls were at higher risk than boys for in utero (OR: 2.6; 95% CI: 1.2 to 5.8) and perinatal (OR: 1.9; 95% CI: 1.0 to 3.7) infection. Recognized mother-to-child transmission risk factors did not explain the higher risk of infection in girls. Conclusions: Girls were at higher risk of early (in utero and perinatal) HIV infection than boys. It is proposed that minor histocompatibility reactions between maternal lymphocytes and infant Y chromosome-derived antigens reduce the risk of HIV transmission in boys.

Original languageEnglish (US)
Pages (from-to)509-513
Number of pages5
JournalJournal of Acquired Immune Deficiency Syndromes
Issue number4
StatePublished - Apr 2006


  • Female
  • Gender
  • HLA
  • Infants
  • Male
  • Retrovirus
  • Vertical transmission

ASJC Scopus subject areas

  • Infectious Diseases
  • Pharmacology (medical)


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