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Vaccines that contain live, attenuated (weakened) viruses
should not be given to pregnant women. As a precaution,
pregnancy should be avoided for 28 days after receiving such
vaccines. However, if a vaccine is inadvertently
administered, the risk to mother and fetus should be lower
than that from acquiring natural infection because the
disease-causing virus has been attenuated (weakened) and is
less virulent. Examples of vaccines that should not
routinely be given to pregnant women include:
Measles, mumps,
rubella (MMR) vaccine and its component
vaccines are not recommended during pregnancy because of the
theoretical risk to mother and fetus. Measles illness
is suspected to increase the risk of spontaneous abortion or
premature delivery. Exposed women should be given measles
immunoglobulin (purified antibodies to measles) within six
days of exposure. MMR can be administered after delivery
before hospital discharge if women are not immune to rubella
or need a second dose of measles vaccine.
Mumps
is not associated with fetal abnormalities during pregnancy, but if
a pregnant woman contracts mumps in the first trimester the risk of
spontaneous abortion is higher.
Rubella during pregnancy is
associated with the development of a number of abnormalities in the
fetus, including mental retardation, deafness and heart defects,
known as congenital rubella syndrome. No cases of this syndrome have
been detected in women inadvertently vaccinated while pregnant or
who became pregnant within 28 days of vaccination.
Should a
pregnant woman inadvertently receive MMR vaccine, she should be
counseled about the theoretical risk to the fetus however
vaccination in pregnancy is not an automatic reason for termination
of the pregnancy.
Varicella vaccine is
not recommended for pregnant women.
Varicella infection (chickenpox) in pregnant women is associated
with an increased risk of pneumonia, often requiring admission to
the hospital, and a small risk of limb abnormalities in the fetus.
Newborn infants whose mothers acquire varicella within 5 days of
delivery are at increased risk of acquiring severe varicella
infection. Because of the increased susceptibility of mother and
infant to harm from varicella infection, varicella immunoglobulin
(purified antibodies to varicella) is recommended for exposed
pregnant women within 96 hours of exposure and for exposed newborns
within 48 hours of birth. While varicella immunoglobulin may not
prevent varicella in all cases, it is likely to lessen the severity
of the illness. Pregnancy in a household contact is not a reason to
defer vaccination in a susceptible child. Pregnant women who do not
have protection against varicella should receive the vaccine after
delivery and a second dose four to eight weeks later. Varicella vaccine can be given after delivery before hospital
discharge if women previously have not had chickenpox, have had only
one varicella vaccine or have never received vaccine (a second dose
can be given one month later).
Live, attenuated influenza vaccine (LAIV) should not
be administered to pregnant women. The
inactivated trivalent
influenza vaccine (TIV) is recommended for all women
(regardless of time in pregnancy) who will be pregnant
during the influenza season.
Oral poliovirus vaccine (OPV) is
not available in the United States
and is not recommended for use in pregnancy. When exposure to polio
is likely, pregnant women should receive the
inactivated poliovirus vaccine [IPV].
Yellow fever vaccine
should be administered to pregnant women only if travel to an
endemic area is unavoidable and the risk of exposure is very high.
The safety of this vaccine in pregnancy has not been established.
Typhoid vaccines
have not been studied in pregnancy. One typhoid vaccine is composed
of killed bacteria and given by injection. The other, an oral
vaccine, is composed of weakened bacteria and should not be given to
pregnant women.
Bacille Calmette Guerin (BCG) vaccine
is used to prevent
tuberculosis in some areas of the world. Although it has not been
reported to cause harmful effects to the fetus, it is not recommended for use in pregnancy
Vaccinia vaccine (smallpox)
has not been associated with fetal abnormalities. Smallpox infection
causes more severe disease in pregnant than non-pregnant women.
While routine vaccination in pregnant women is not recommended, the
risks of clinical smallpox to mother and infant from clinical
smallpox outweigh the risks of the vaccine.
 
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