November 2002
Vertical Transmission

“Vertical transmission” is the transmission of the HIV virus from an infected mother to her child. There are three main ways this can happen. It may occur while the mother is pregnant (in utero), it can happen during the birthing process or after birth usually from breast-feeding. Researchers have identified several risk factors that are known to effect possible mother-to-child transmission.

First is the viral load of the mother while she is pregnant. This is probably the area in which prevention of child HIV can be most effective. Prenatal infection of a fetus can occur any time during the pregnancy but usually happens right before delivery. If a mother is on HAART (three or more medications) and her viral load during gestation can be maintained at undetectable levels it nearly eliminates any chance of vertical transmission. Without treatment of any kind about 20-25% of the babies born to HIV infected mothers will become positive. Even if the mother doesn’t take antivirals until she is in labor and her baby is put on short- term treatment; of one dose of nevirapine (Viramune) and six weeks of AZT, transmission of HIV to the child can be cut by 50%. Transmission rates are lowest if the mother takes AZT during the last six months of her pregnancy and her child is put on the short-term treatment.

The second risk factor that effects vertical transmission is the length of time the delivery takes. The longer a delivery takes the longer the baby is exposed directly to its mother’s blood. I have read that if a woman’s viral load is less than 1000 it can be less risk (1%) for her to go into labor and have a natural childbirth. In this process the mother is given AZT during labor and the child is put on short-term treatment. Otherwise the safest option is to have a quick Cesarean section before the onset of labor or rupture of the membranes occurs. AZT is then given a few hours before the C-section and the baby is given the short-term treatment.

The third risk factor is breast-feeding. The HIV virus is most often transmitted within the first six months of beginning breast-feeding. This is the most common way of mother-to-child HIV transmission. Unfortunately many mothers especially in the developing world have no other option than to breast feed their children. In many of these areas of the world the water is so contaminated with bacteria even if formula was provided it would be more dangerous to the survival of the child than having it’s HIV infected mother breast feed it. But in countries that have safe and good water supplies it is much better to use formula than take the chance associated with breast-feeding.

In closing I would like to encourage anyone who wants to have a child to please discuss it with his or her medical provider. Also take into account the nutritional aspects that can help minimize mother-to-child HIV transmission. Keeping an adequate level of Vitamin A in your body for example.
Take care, Erica

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