Risk factors for vertical transmission of the human immunodeficiency virus type 1 - Revista Brasileira de Ginecologia e Obstetrícia

One of the most important advances in the control of the spread of infection with type 1 human immunodeficiency virus (HIV-1) occurred within the context of vertical transmission (VT), with a reduction from levels of more than 40% to levels of less than 3%. Technological progress together with a better physiopathological understanding of this infection has permitted the determination of the situations and factors that increase the rates of perinatal transmission of the virus, indicating which interventions are most adequate for its control. The situations of higher risk for VT of HIV involve maternal, adnexal, obstetrical, fetal, viral, and postnatal factors. Among maternal factors, particularly important is viral load, the major indicator of the risk of this form of transmission. However, despite its relevance, viral load is not the only variable in this equation, with the following factors also playing important roles: use of illicit drugs, multiple sex partners and unprotected sex, malnutrition, smoking habit, advanced maternal disease, and lack af access or compliance with antiretroviral drugs. Among the adnexal factors are prolonged chorion-amniorrhexis, loss of placental integrity, and the expression of secondary receptors in placental tissue. Among the obstetrical factors, it should be remembered that invasive interventions in the fetus or amniotic chamber, internal cardiotocography, type of delivery, and contact of the fetus/newborn infant with maternal blood are also important elements to be controlled. Among the fetal factors are the expression of secondary HIV-1 receptors, genetic susceptibility, reduced cytotoxic T-lymphocyte function, and prematurity. Among the viral factors, mutations and syncytium-inducing strains are believed to be risk factors for VT. Finally, there are postnatal factors represented by an elevated viral load in maternal milk, a low antibody concentration in this fluid, clinical mastitis and nipple lesions, which can be grouped within the context of breast-feeding.