The AIDS virus can be transmitted from mother to child during pregnancy, during childbirth or during breastfeeding. Even though the virus has been isolated in foetal tissues from as early as the 12th week of pregnancy, at least two thirds of infections in breastfeeding infants were acquired during the last trimester of pregnancy, labour or even in the birth canal.
International, retrospective studies have shown that HIV-1 is transmitted from mother to foetus and newborn in between 13% and 48% of cases, while HIV-2 (widespread in Africa) is transmitted less frequently. Currently, it is not possible to give a definitive answer to an HIV-positive woman wanting to have a child about the risk of her passing on the virus to her child. This risk is neither a certainty nor can it be ruled out.
HIV: preventing transmission in the event of pregnancy
There are many treatments based on the belief that viral load is the main factor in determining transmission. The main medication used to reduce viral load during pregnancy is zidovudine, which involves minor side effects for foetuses and newborns.
The injection of hyperimmune, anti-HIV globulins or neutralising monoclonal antibodies can reduce the amount of virus circulating freely in the body and, during childbirth, can reduce the virus in circulation and also prevent it from passing through the placenta. However, in addition to high production costs, the preparation of anti-HIV immunoglobulins also requires asymptomatic donors to be found with a high level of neutralising antibodies, who also need to come from the same geographic region as the recipient.
The time of childbirth is crucial in the vertical transmission of HIV, and there are also types of childbirth that could be decisive in the prevention of infection. Transmission during childbirth can happen in a number of ways: transmission can occur due to direct contact with infected vaginal secretions or with blood during the passage of the foetus, and so a caesarean section or cleaning of the birth canal with substances capable of neutralising HIV could be used to prevent transmission.
All pregnant women should undergo screening for HIV in order to keep the risk of transmission to children to a minimum. If a woman knows that she is HIV-positive and has already had children, it is important for all of her children to undergo HIV tests, even if some of them are older and appear to be in perfect health.