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Vaccines that contain live,
attenuated viruses or bacteria 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 or bacterium has
been attenuated 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 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.
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 and were subsequently
monitored by the CDC.
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 this antibody preparation 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 in the postpartum period and a second dose four to
eight weeks 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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