New Mexico AIDS Infonet Fact Sheet Number 611
PREGNANCY & HIV

HOW DO BABIES GET AIDS?

The virus that causes AIDS, HIV, can be transmitted from an infected mother to her newborn child. Without treatment, about 20% of babies of infected mothers get infected.

Mothers with higher viral loads are more likely to infect their babies. However, no viral load is low enough to be "safe". Infection can occur any time during pregnancy, but usually happens just before or during delivery.

The baby is more likely to be infected if the delivery takes a long time. During delivery, the newborn is exposed to the mother's blood.

Drinking breast milk from an infected woman can also infect babies. Mothers who are HIV-infected should not breast-feed their babies.

HOW CAN WE PREVENT INFECTION OF NEWBORNS?

Mothers can reduce the risk of infecting their babies if they:

• Use antiviral medications,

• Keep the delivery time short, and

• Don't breast-feed the baby

Use antiviral medications: The risk of transmitting HIV drops from 20% to 8% or less if antiviral medications are used. Transmission rates are lowest if the mother takes AZT during the last six months of her pregnancy, and the newborn takes AZT for six weeks after birth.

Even if the mother does not take antiviral medications until she is in labor, the transmission rate can be cut by almost half. Two methods have been studied:

• AZT and 3TC during labor, and for both mother and child for one week after the birth.

• One dose of nevirapine during labor, and one dose for the newborn, 2 to 3 days after birth.

Although these shorter treatments do not work as well, they are less expensive and might be helpful in developing countries. Unfortunately, resistance to nevirapine develops in many women who use it when they are pregnant. This resistance can be transmitted through breast feeding. Researchers are reviewing whether a short course of nevirapine should be used to prevent transmission of HIV to a newborn.

Keep delivery time short: The risk of transmission increases with longer delivery times. If the mother uses AZT and delivers her baby by cesarean section (C-section), she can reduce the risk of transmission to about 2%.

Do not breast-feed the baby: There is about a 14% chance that a baby will get HIV infection from infected breast milk. This risk can be eliminated if HIV-infected women do not breast-feed babies. Baby formulas should be used.

In developing countries, however, there might not be clean water to prepare baby formulas. The World Health Organization believes that the risk of transmitting HIV is less than the health risk of using contaminated water.

HOW DO WE KNOW IF A NEWBORN IS INFECTED?

Most babies born to infected mothers test positive for HIV. Testing positive means you have HIV antibodies in your blood. See Fact Sheet 102 for more information on HIV tests. Babies get HIV antibodies from their mother even if they aren't infected with the virus.

If babies are infected with HIV, their own immune systems will start to make antibodies. They will continue to test positive. If they are not infected, the mother's antibodies will gradually disappear and the babies will test negative after about 6 to 12 months.

Another test, similar to the HIV viral load testt, can be used to find out if the baby is infected with HIV. Instead of antibodies, these tests detect the HIV virus in the blood.

WHAT ABOUT THE MOTHER'S HEALTH?

Recent studies show that HIV-positive women who get pregnant do not get any sicker than those who are not pregnant. That is, becoming pregnant does not appear to be dangerous to the health of an HIV-infected woman.

However, although AZT by itself can help protect newborns from HIV, it is not the best choice for the mother's health. Combination therapies using at least three drugs are the standard treatment. If a pregnant woman takes AZT by itself, HIV might develop resistance to it. Then AZT might not be useful any more. See Fact Sheet 126 for more information on resistance.

On the other hand, combination therapy might cause birth defects, especially during the first three months. Studies of pregnant women who used combination therapy show virtually no HIV-infected newborns and no unusual birth defects.

A pregnant woman should consider all of the possible side effects of antiviral medications. Some of them could be worse for pregnant women. For example, in January 2001, the FDA warned pregnant women not to use both ddI and d4T in their antiviral treatment due to a high rate of a dangerous side effect called lactic acidosis.

Some doctors suggest that women interrupt their treatment during the first 3 months of pregnancy for two reasons:

• The risk of missing doses due to nausea and vomiting during early pregnancy

• The risk of HIV developing resistance to the medications that the woman is taking.

If you have HIV and you are pregnant, or if you want to become pregnant, talk with your doctor about your options for taking care of yourself and reducing the risk of HIV infection or birth defects for your new child.

THE BOTTOM LINE

An HIV-infected woman who becomes pregnant needs to think about her own health and the health of her new child.

The risk of transmitting HIV to a newborn can be cut to just 2% if the mother takes AZT during the last 6 months of her pregnancy, delivers her child by Cesarean section, and the newborn takes AZT for six weeks.

Pregnancy does not seem to make the mother's HIV disease any worse. However, some medications used to fight HIV or to treat opportunistic infections might cause birth defects. This is especially true during the first 3 months of pregnancy. If a mother chooses to stop taking some medications during pregnancy, her HIV disease could get worse.

Any woman with HIV who is thinking about getting pregnant should carefully discuss treatment options with her doctor.