, Volume 154, Issue 7, pp 542-545

Mother-to-child transmission of human immunodeficiency virus type 1: Influence of parity and mode of delivery

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In a national prospective study of risk factors for mother-tochild 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).


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.