title: Potential risk factors for vertical HIV-1 transmission in Catalonia, Spain: the protective role of cesarean section. The Working Group on HIV-1 Vertical Transmission in Catalonia.
abstract: OBJECTIVE
  To evaluate the roles of certain potential risk factors on the vertical transmission of HIV-1.
  
  
  METHODS
  Prospective registry of infants born to HIV-1-infected women in Catalonia (north-east Spain) from 1987 to 1992.
  
  
  METHODS
  A total of 599 infants, born in Catalan hospitals to 520 women who were identified as being HIV-1-infected during gestation or at delivery, were included. Data on mode of delivery, birth weight, gestational age and breast-feeding as well as the mother's age, her route of HIV-1 infection, clinical stage and p24 antigenaemia, were recorded. HIV-1 infection status of 489 (82%) of the infants was determined according to the criteria of the US Centers for Disease Control and Prevention. Risk estimates and odds ratio (OR) were calculated and logistic regression was performed.
  
  
  RESULTS
  The overall rate of vertical transmission was 18.6% (95% confidence interval, 15.2-22.0%). Multivariate analyses revealed that Cesarean section was associated with a lower rate of vertical transmission (OR = 0.3; P = 0.001), as was maternal HIV-1 infection via injecting drug use (OR = 0.44; P = 0.02). Breast-feeding (OR = 6.9; P = 0.001), very low birth weight (< 1500 g; OR = 6.3; P = 0.001) and p24 antigenaemia (OR = 4.6; P = 0.04) were all related to increased risk. The crude rate of HIV-1 transmission was 6% among Cesarean births compared with 21% for infants born via vaginal deliveries. The population-attributable risk for vaginal deliveries was 61.7%.
  
  
  CONCLUSIONS
  The results show a protective effect of Cesarean section in the absence of zidovudine prophylaxis. However, current research should be directed towards the individual and combined effects that antiretroviral agents and Cesarean section may have on mother-to-child HIV-1 infection.
authors.affiliation: Centre for Epidemiological Studies on AIDS in Catalonia CEESCAT, Hospital Universitari Germans Trias i Pujol, Badalona.
authors.forename: A
authors.initials: A
authors.lastname: Maguire
authors.forename: E
authors.initials: E
authors.lastname: Sánchez
authors.forename: C
authors.initials: C
authors.lastname: Fortuny
authors.forename: J
authors.initials: J
authors.lastname: Casabona
mesh_terms: D000328:Adult; D002585:Cesarean Section; D005260:Female; D016655:HIV Core Protein p24 / Q000097:blood; D015658:HIV Infections / Q000517:prevention & control / Q000635:transmission* / Q000821:virology; D015497:HIV-1 / Q000276:immunology; D006801:Humans; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical / Q000517:prevention & control*; D008297:Male; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000821:virology; D011446:Prospective Studies; D012042:Registries; D012307:Risk Factors; D013030:Spain
chemical_list: D016655:HIV Core Protein p24