106 INFLUENCE OF PARITY ON MOTHER-TO-CHILD TRANSMISSION OF HIV

Abstract

Top of pageAbstract Background: Risk factors for mother-to-child transmission of HTV are still incompletely defined. An effect of parity has hitherto not been described. Design: In a national prospective study, 316 children of HIV-positive mothers were followed up for at least 6 months. Infection status was determined in 254 of them according to the criteria of the Working Group on Mother-to-Child Transmission of HTV (AIDS 1993, 7:1139-1148) or, in children under 15 months, by concordant (positive or negative) results of virus detection tests in at least 2 samples by at least 2 methods (PCR, culture, antigen after immune complex disruption). Transmission rate was 18.1%. The effect of potential risk factors on transmission rate was analysed. Results: Univariate analysis showed an association between primiparity and increased transmission rate: odds ratio (OR) 2.2, 95%-confidence interval (95%-CI) 1.1-4.6, p<0.05. Logistic regression confirmed this association (adjusted OR 2.4) and showed, in addition, a negative association between transmission rate and elective cesarean section (OR 0.36, 95%-CI 0.13-0.97, p<0.05). The effect of primiparity was less pronounced in combination with elective cesarean section (OR 1.7) than with other delivery modes (OR 2.5, difference not significant). HIV-infected children older than two years were less likely to get a younger sibling during the observation period than their uninfected counterparts (0 of 22 vs. 10 of 101, 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.