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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:
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.
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