OBJECTIVES: To estimate the risk of mother-to-child transmission (MTCT) of HIV-1 and evaluate the effect of preventive methods on vertical transmission of HIV, such as: use of AZT by pregnant women during the prenatal period, labor and delivery; use of AZT in newborns; replacement of breastfeeding by formula; and indication of cesarean section. METHODS: This was a cohort study. Data was collected from medical records of pregnant women and of children followed at reference health centers for HIV/AIDS patients. To estimate the risk of MTCT we divided the number of mothers whose children acquired the virus through vertical transmission by the total number of mothers included in the study; the relative risks were calculated with a CI=95%. Occurrence of transmission was regarded as a dependent variable, the other factors (maternal age, use of oral AZT and use of AZT syrup, gestational age and breastfeeding) were considered as independent variables. Mantel-Haenszel's techniques were used in this analysis to control the possible effect of some variables. RESULTS: The occurrence of HIV in MTCT was identified in 144 children. Fourteen were classified as infected. Risk of transmission was of 0.097 (95% CI; 0.030-0.163). The risk of HIV vertical transmission was smaller in women under thirty years of age when compared with older ones. In the univariate analysis, the MTCT risk was significantly associated with maternal age, prenatal care, use of oral AZT and use of AZT syrup, gestational age and breastfeeding. CONCLUSION: This study showed that the implementation of preventive measures is important in the prevention of mother-to-child transmission of HIV, providing a risk reduction of almost 40% when compared to that before use of these preventive measures.
Mother-to-child or vertical transmission; HIV; Acquired immunodeficiency syndrome; Risk factors; Protective measures
