HOW DO BABIES GET AIDS?
The virus that causes AIDS can be transmitted from an infected mother to her newborn child. Without treatment, about 20-30% of babies of infected mothers get HIV.
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 generally not breast-feed their babies. To reduce the risk of HIV infection when the father is HIV-positive, some couples have used sperm washing and articial insemination.
HOW CAN WE PREVENT INFECTION OF NEWBORNS?
Mothers can reduce the risk of infecting their babies if they:
- Use antiretroviral medications (ARVs),
- Keep the delivery time short, and
- Take precautions with breast feeding
Use antiretroviral medications (ARVs): The risk of transmitting HIV is extremely low if ARVs are used. Transmission rates are only 1% - 2% if the mother takes combination antiretroviral therapy (ART). The rate is about 4% when the mother takes AZT (also known as ZDV or Retrovir) 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 ARVs until she is in labor, two methods cut transmission by almost half.
- 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.
Combining nevirapine and AZT during labor and delivery cuts transmission to only 2%. However, resistance to nevirapine can develop in up to 40% of women who take the single dose. This reduces the success of later ART for the mother. Resistance to nevirapine can also be transmitted to newborns through breast feeding. However, the shorter regimens are more affordable for developing countries.
Keep delivery time short: The risk of transmission increases with longer delivery times. If the mother uses AZT and has a viral load under 1,000, the risk is almost zero. Mothers with a high viral load might reduce their risk if they deliver their baby by cesarean section (C-section).
Up to 14% of babies may get HIV infection from infected breast milk. Breast feeding is controversial, especially in the developing world. Most transmission from breast feeding occurs within the first two months after birth. On the other hand, replacement feeding within the first two years of life can create additional risks for infant mortality from various diseases.
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. Babies get HIV antibodies from their mother even if they aren't infected.
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 disappear and the babies will test negative after about 6 to 12 months.
Another test, similar to the HIV viral load test, 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. Becoming pregnant is not dangerous to the health of an HIV-infected woman. This is true even if the mother breast-feeds her newborn for a full term (2 years).
However, "short-course" treatments to prevent infection of a newborn are not the best choice for the mother's health. Combination therapies are the standard treatment. If a pregnant woman takes medications only during labor and delivery, HIV might develop resistance to them. This can reduce the future treatment options for the mother.
- A pregnant woman should consider all of the possible problems with ARVs.
- Pregnant women should not use both ddI and d4T in their ARV treatment due to a high rate of a dangerous side effect called lactic acidosis.
- Efavirenz should not be used during pregnancy.
- If you have more than 250 CD4 cells, do not start using nevirapine (Viramune)
- Some health care providers suggest that women interrupt their treatment during the first 3 months of pregnancy for three reasons:
- The risk of missing doses due to nausea and vomiting during early pregnancy, giving HIV a chance to develop resistance
- The risk of birth defects, which is highest during the first 3 months. There is almost no evidence of these birth defects, except with efavirenz.
- Experts disagree whether the use of ART results in a higher risk of premature or low birth weight babies.
If you have HIV and you are pregnant, or if you want to become pregnant, talk with your health care provider 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. Pregnancy does not seem to make the mother's HIV disease any worse.
The risk of transmitting HIV to a newborn can be virtually eliminated with "short course" treatments taken only during labor and delivery. But short treatments increase the risk of resistance to the drugs used. This can reduce the success of future treatment for both mother and child.
However, the risk of birth defects caused by medications is greater 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 health care provider.