Timing and mechanism of perinatal human immunodeficiency virus-1 infection.

There is sufficient evidence indicating a higher vertical HIV-1 transmission rate in the last trimester and during labour compared with the first trimester. Antiretroviral therapy either single or in combination given to the mother during the last trimester and delivery can reduce the viral load in the maternal circulation. Vertical HIV-1 transmission during delivery can be minimized by appropriate timing and route of delivery. Elective Caesarean section before the onset of labour with an intact bag of forewaters provides the least mother-to-fetus microtransfusion compared to other modes of delivery. Since an effective combination of HIV-1 immunoglobulin and HIV-1 vaccine given to the HIV-1 exposed newborns to prevent HIV-1 transmission similar to the viral hepatitis B model is not firmly established at present, postexposure antiretroviral prophylaxis and nonbreast-feeding are advocated for infants born from the HIV-1 infected mothers. In cases of advanced stage of maternal HIV-1 infection, and in developing areas where malnutrition prevails, an adequate supply of essential micronutrients is proposed as an adjunctive measure to reduce HIV-1 perinatal transmission.