title: Mother-to-child transmission of human immunodeficiency virus type 1: influence of parity and mode of delivery. Paediatric AIDS Group of Switzerland.
abstract: In a national prospective study of risk factors for mother-to-child transmission of human immunodeficiency virus (HIV), 316 children of HIV-positive mothers were followed up for at least 6 months. Infection status was determined in 254 of them and 46 were found to be infected giving a transmission rate of 18.1%. Univariate analysis of potential risk factors for mother-to-child transmission showed an association between primiparity and increased transmission rate: odds ratio 2.2, 95% confidence interval (CI) 1.1-4.6, P < 0.05. Analysis by logistic regression confirmed this association (adjusted odds ratio 2.4) and showed, in addition, a negative association between transmission rate and elective Caesarean section (adjusted odds ratio 0.36, 95% CI 0.13-0.97, P < 0.05). The effect of primiparity was less pronounced in combination with elective Caesarean section (odds ratio 1.7) than with other delivery modes (odds ratio 2.5, difference not significant). HIV-infected children were less likely to experience the birth of a younger sibling during the observation period than their uninfected counterparts (2 of 46 vs 27 of 208, P < 0.05 by logrank test).
  
  
  CONCLUSIONS
  Primiparous women appear to transmit HIV to their children at a higher rate. This could be explained by increased intrapartum transmission because of longer and more complicated labour in primiparas and/or by a self-selection of women with lower risk of transmission among those deciding to have additional children.
authors.affiliation: Abteilung für Neonatologie, Frauenklinik, Kantonsspital, St. Gallen, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Kind
mesh_terms: D000328:Adult; D002585:Cesarean Section; D005113:Extraction, Obstetrical; D005260:Female; D005500:Follow-Up Studies; D015658:HIV Infections / Q000517:prevention & control / Q000635:transmission*; D015497:HIV-1; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical; D008297:Male; D016017:Odds Ratio; D010298:Parity; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors