Transmission

Almost all HIV-infected children acquire the virus from their mothers before or during birth or through breastfeeding. In the United States, approximately 25 percent of pregnant HIV-infected women not receiving AZT therapy have passed on the virus to their babies. The rate is significantly higher in developing countries.

Pregnancy and Birth

Most mother-to-child transmission (MTCT), estimated to cause more than 90 percent of infections worldwide in infants and children, probably occurs late in pregnancy or during birth. Although the precise mechanisms are unknown, scientists think HIV may be transmitted when maternal blood enters the fetal circulation, or by mucosal exposure to virus during labor and delivery. The role of the placenta in maternal-fetal transmission is unclear and the focus of ongoing research.

The risk of MTCT is significantly increased if the mother has advanced HIV disease, increased levels of HIV in her bloodstream, or fewer numbers of the immune system cells—CD4+ T cells—that are the main targets of HIV.

Other factors that may increase the risk are maternal drug use, severe inflammation of fetal membranes, or a prolonged period between membrane rupture and delivery. A study sponsored by NIAID and others found that HIV-infected women who gave birth more than 4 hours after the rupture of the fetal membranes were nearly twice as likely to transmit HIV to their infants, as compared to women who delivered within 4 hours of membrane rupture.

Breastfeeding

HIV also may be transmitted from a nursing mother to her infant. Studies have suggested that breastfeeding introduces an additional risk of HIV transmission of approximately 10 to 14 percent among women with chronic HIV infection. In developing countries, an estimated one-third to one-half of all HIV infections are transmitted through breastfeeding.

WHO recommends that all HIV-infected women be advised about both the risks and benefits of breastfeeding for their infants so they can make informed decisions. In countries where safe alternatives to breastfeeding are readily available and economically feasible, this alternative should be encouraged. In general, in developing countries where safe alternatives to breast-feeding are not readily available, the benefits of breastfeeding in terms of decreased illness and death due to other infectious diseases greatly outweigh the potential risk of HIV transmission.

Transfusion

Prior to 1985 when screening of the nation's blood supply for HIV began, some children as well as adults were infected through transfusions with blood or blood products contaminated with HIV. A small number of children also have been infected through sexual or physical abuse by HIV-infected adults.

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Important disclaimer: The information on pkids.org is for educational purposes only and should not be considered to be medical advice. It is not meant to replace the advice of the physician who cares for your child. All medical advice and information should be considered to be incomplete without a physical exam, which is not possible without a visit to your doctor.