title: HIV-1 infection in a population-based twin sample.
abstract: OBJECTIVE
  To examine factors associated with perinatal HIV-1 transmission among twins.
  
  
  METHODS
  We identified twins delivered by a population-based cohort of HIV-infected mothers on New York State Medicaid. Tested algorithms were applied to Medicaid files to identify HIV infection in mothers and twins. The HIV transmission rate 3 years after delivery was assessed from Kaplan-Meier curves. Proportional hazards models with adjustment for twin clustering were used to determine the relative hazard (RH) of transmission.
  
  
  RESULTS
  In 35 twin pairs, transmission was 20.5%. The risk of transmission was increased significantly for advanced maternal HIV infection (rh = 10.8, 95% confidence interval 2.11, 54.9). We found no association of birth order with twin HIV status.
  
  
  CONCLUSIONS
  These data suggest that maternal stage of disease plays a greater role in vertical HIV transmission than birth order. To prevent maternal-child HIV transmission, reducing maternal viral load is likely to have a greater impact than modifying delivery factors.
authors.affiliation: New York University Medical Center-Bellevue Hospital Center, New York, USA.
authors.forename: K
authors.initials: K
authors.lastname: Krasinski
authors.forename: B J
authors.initials: BJ
authors.lastname: Turner
authors.forename: W W
authors.initials: WW
authors.lastname: Hauck
authors.forename: T R
authors.initials: TR
authors.lastname: Fanning
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004200:Diseases in Twins; D005260:Female; D015658:HIV Infections / Q000453:epidemiology / Q000635:transmission*; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical; D008297:Male; D009518:New York / Q000453:epidemiology; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis*; D011272:Pregnancy, Multiple; D016016:Proportional Hazards Models; D012306:Risk; D019562:Viral Load