Updated: Enero 29, 2009
Ideally, women of child-bearing age should be immunized before becoming pregnant to protect their babies against serious diseases. For instance, rubella causes serious damage to the unborn fetus and is preventable by rubella vaccine. Varicella (chickenpox) can cause birth defects in the fetus and fatal pneumonia in the mother; it is preventable by varicella vaccine. Tetanus in the newborn, often fatal, is prevented if the mother has been immunized, as is the case with many other vaccine-preventable diseases.
Although many medications, including some vaccines, are avoided during pregnancy because of potential harm to the mother or fetus, some vaccines are actually recommended for pregnant women. Certain immunizations during pregnancy will enhance the mother’s health and others will protect the child by means of the mother’s antibodies that remain in the child for the first 3-6 months of life.
While certain drugs may harm the developing fetus, the risk of a developing fetus being harmed by vaccination of the mother during pregnancy remains only theoretical. Currently, no evidence exists of risk from vaccinating pregnant women with any inactivated viral or bacterial vaccine or toxoid. Live attenuated vaccines, including MMR and varicella, are of greater theoretical concern, so it is recommended that women avoid pregnancy as a precautionary measure for at least 28 days after administration of these vaccines. This 28-day rule is used even though there is no evidence in prior studies of damage to the fetus when the pregnant mother received one of these vaccines.
Pregnant women and health care providers should always consider the risks and benefits of the vaccine as well as the risks of the disease before administering or receiving the vaccine. Immunization before conception is always preferred to immunization during pregnancy to prevent disease in the child. After delivery, women susceptible to rubella or varicella should be immunized with MMR or varicella vaccine before discharge from the hospital.
Breast-feeding does not interfere with the response to the vaccines recommended for adults. Although rubella vaccine virus has been found in human milk, this and other vaccines provided to the mother during pregnancy or immediately post partum have not been shown to interfere with the immune response of children to the vaccine. Also, no child has developed illness from a vaccine administered to their mother. Human milk contains antibodies and other factors that may help protect infants against many infectious diseases.
The Centers for Disease Control and Prevention (CDC) has published a recommended adult immunization schedule, including for pregnant women.
Influenza. Pregnant women who become infected with influenza viruses are at increased risk of hospitalization, serious medical complications, and adverse pregnancy outcomes. Immunization of the pregnant woman with inactivated influenza virus vaccine is effective at reducing febrile respiratory infections in pregnant woman. Immunizing the mother during pregnancy also protects her newborn because she passes immune antibodies across the placenta (influenza antibodies are actually higher in umbilical cord blood than in the mother’s blood). Infants with influenza virus infection account for many hospitalizations and are predisposed to bacterial respiratory infections. Childhood deaths associated with influenza virus infection occur most frequently in infants less than 6 months of age. Unfortunately, during the first 6 months of life, there are no vaccines or anti-influenza virus drugs available. For these reasons, pregnant women should receive inactivated influenza virus vaccine and those who will be helping to care for the newborn should be vaccinated as well. Studies of influenza vaccination of more than 2,000 pregnant women have demonstrated no adverse effects to the fetus from the vaccine. However, the nasal influenza vaccine should not be given to pregnant women because it is a live virus vaccine.
Tetanus. Tetanus in newborn infants—once common throughout the Americas—is prevented if the mother has been immunized. This is because an immune mother passes antibodies to the baby across the placenta. The mother is immune if she has been immunized before becoming pregnant or during pregnancy. An expectant mother whose tetanus immunization status is uncertain or whose last immunization was more than 10 years ago should be immunized against tetanus. This is usually given combined with diphtheria toxoid vaccine (a product called Td). Recently a new Td vaccine that also contains vaccine for pertussis has been licensed for adults (Tdap) including for use for women in the child-bearing age group. Pregnancy is not a contraindication to Tdap immunization. However, at this time, CDC recommends that pregnant women who received the last tetanus toxoid-containing vaccine less than 10 years ago receive Tdap in the post-partum period according to the routine vaccination recommendations. If the last dose of tetanus toxoid-containing vaccine was more than 10 years before, they prefer that she be immunized with Td during the second and third trimester instead of Tdap.
Generally, live-attenuated vaccines are contraindicated for pregnant women because of the theoretical risk of transmission of the vaccine virus to the fetus. The following live, attenuated vaccines should not be administered during pregnancy except in unusual circumstances:
Varicella. Varicella (or, chickenpox) vaccine is universally recommended for all children and nonpregnant adults who are susceptible, but it is not given to pregnant women. Pregnant women who develop chickenpox (varicella) are at increased risk of having severe illness and a small proportion of their newborns may be born with congenital varicella syndrome. Susceptible women who are exposed to varicella (or shingles, which is caused by the same virus) should receive varicella-zoster immune globulin (VariZIG) within 96 hours, which may prevent or modify infection. Antiviral drugs usually are reserved for pregnant women with severe chickenpox illness. Infants born to mothers who had chickenpox within 5 days of delivery are also given VariZIG within 48 hours of delivery to prevent them from having serious illness. Vaccination with varicella live virus vaccine during pregnancy is not recommended, although inadvertent vaccinations have not been associated with adverse outcomes. A pregnant household member is not a contraindication for varicella immunization of a child within that household, however.
The varicella vaccine virus rarely spreads from a vaccinated person who develops rash to susceptible persons within households. The risk for a susceptible pregnant woman and her fetus should be very low after this type of exposure. However, the pregnant woman who believes that she is susceptible to chickenpox and who has a household exposure to someone who develops rash after varicella immunization should inform her physician.
Ideally, women should be immune to chickenpox before pregnancy, either from vaccine or chickenpox. At the completion of pregnancy, susceptible women should receive the first dose of chickenpox vaccine before discharge from the healthcare facility. A second dose should be administered four to eight weeks later.
Measles, mumps, and rubella. Measles, mumps, and rubella live virus vaccines—usually given together as MMR—should not be administered during pregnancy. However, because measles increases the risk for spontaneous abortion or premature delivery, pregnant susceptible women are given immune globulin within six days of exposure. The mumps virus has not been associated with problems during pregnancy. Wild rubella virus infection in early pregnancy has a high risk of causing congenital rubella syndrome (CRS) in fetuses. This is a devastating disease that is preventable by the use of vaccine prior to pregnancy. Pregnant women are screened early in pregnancy to be certain that they are immune. If susceptible and exposed, the pregnant woman and her physician together will need to consider her options. The rubella-susceptible woman should be immunized with MMR in the immediate post-partum period. However, CDC has followed the outcomes of inadvertent rubella vaccination of pregnant women and no cases of CRS have been detected.
Transmission of MMR vaccine viruses within households has not been demonstrated (except rubella virus from nursing mothers to their infants). Thus, susceptible children should be immunized whether or not there is a pregnant household contact.
Yellow fever. Live attenuated yellow fever vaccine is not known to cause developmental malformations. It is only administered to pregnant women if travel to an endemic area where she is going to be at risk of exposure to yellow fever is unavoidable.
Typhoid fever. Neither the live attenuated Ty21a nor the Vi polysaccharide typhoid fever vaccines have been tested in pregnant or breastfeeding women. Some experts might consider the polysaccharide vaccine for pregnant or lactating women if travel to an endemic area is unavoidable and she is likely to be at risk of exposure to Salmonella typhi (the cause of typhoid fever).
The following vaccines should be considered for pregnant women who are at risk for acquiring or being exposed to these diseases. Because spontaneous abortion occurs more commonly in the first trimester of pregnancy, some obstetricians prefer to avoid administering vaccines during this time, if possible, to avoid any temporal associations that might occur. Specific recommendations for travel by pregnant women (and others) can be obtained at www.cdc.gov/travel.
Hepatitis B virus. Hepatitis B (HBV) infection during pregnancy can result in severe disease for both the mother, the fetus, and ultimately for the neonate. Immunization is recommended universally in the United States for everyone under the age of 18 years and those older than that who have increased risk of exposure. Pregnancy is not a contraindication for HBV immunization and vaccine should be given to persons with occupational or lifestyle risks, special patients risk groups (such as those undergoing hemodialysis), those who have another sexually transmitted disease, household and sexual contacts of HBV carriers, prison inmates, and for international travelers to endemic areas. All pregnant women should have early prenatal screening for immunity and, if susceptible and if they have a risk factor, should be immunized.
All pregnant women should be screened for active hepatitis B virus infection because most women who are infected do not know it and, if they have hepatitis B infection, the newborn infant will need to receive a birth dose of hepatitis B vaccine and hepatitis B immune globulin—giving both within hours of birth reduces the likelihood that the child will become infected with hepatitis B virus and, if infected, reduces the chances that the baby will be chronically infected.
Pneumococcal infection. Pneumococcal polysaccharide vaccine (PPV23) is indicated for specific medical conditions (such as asplenia [absence of the spleen], metabolic, renal, cardiac, and pulmonary diseases, and immunosuppression). Pregnant women with those conditions should also receive the vaccine, preferably prior to pregnancy—but it can be given to a pregnant woman if she has not previously been immunized.
Rabies exposure. The risk of rabies far exceeds the theoretical risk from the vaccine if the expectant mother has been exposed to the disease.
Meningococcal infection. Studies of pregnant women immunized with meningococcal polysaccharide vaccine and their newborns have not demonstrated any adverse effects. This means that that vaccine would likely be safe for a pregnant woman at high risk for meningococcal infection. Because the new meningococcal conjugate vaccine (MCV4) is the preferred vaccine for people 11–55 years of age, many experts would prefer to give MCV4 in this setting, although there are no data on the safety of MCV4 during pregnancy.
Hepatitis A. Pregnant women are at risk of acquiring hepatitis A virus infection if there is someone infected in the household, if they have occupational exposure, or if traveling to areas where hepatitis A is endemic. Although formal studies of hepatitis A vaccine in pregnant women have not been performed, the vaccine is produced from inactivated virus so the theoretical risk for the fetus should be low. The vaccine has been used in pregnant women without adverse events having been reported. Because international travel is now the most frequent source of exposure for Americans to hepatitis A, vaccination prior to travel to endemic areas is particularly important. For pregnant women who have been exposed to hepatitis A virus, testing for susceptibility may be warranted but should not delay the administration of immune globulin (“gamma globulin”).
Polio. Wildtype polioviruses have been eliminated in the United States and thus there is not usually an indication for immunization of the pregnant woman except for those women traveling to endemic areas. If polio vaccine is indicated, only the inactivated vaccine should be given to a pregnant woman and not the oral live virus vaccine.
Anthrax. Women vaccinated against anthrax earlier in life have had no problems with their pregnancies or babies. No studies have been published regarding use of anthrax vaccine among pregnant women, although an ongoing study by the Naval Health Research Center and the National Center for Birth Defects and Developmental Disabilities suggest that children born to women who were immunized with anthrax vaccine in the first trimester of pregnancy could have an increased risk of birth defects. The Advisory Committee for Immunization Practices recommends that pregnant women not be vaccinated against anthrax. However, in the circumstances of an exposure to aerosolized anthrax (such as might occur in a bioterror attack), the theoretical risks of the vaccine would likely be far less than the risk of disease; pregnant women should be vaccinated against anthrax only if the potential benefits of vaccination outweigh the potential risks to the fetus.
Human papillomavirus. Although the initial clinical trials of human papillomavirus (HPV) vaccine specifically excluded pregnant women, 1,244 pregnancies occurred in the vaccine group and 1,272 occurred among the women who received placebo. There were no differences in the rates of miscarriage, late pregnancy fetal deaths, or birth defects among their babies. Infants of 500 women who were breast feeding when they received vaccine had no more adverse events than did those who got placebo and none of the events was considered related to vaccine. The FDA has established a registry to record the outcomes of pregnancy among women who are inadvertently given HPV vaccine while pregnant.
CDC (2008). Guideing principles for development of ACIP recommendations for vaccination during pregnancy and breastfeeding. MMWR 57(21): 580.
CDC (2009). Recommended adult immunization schedule—United States, 2009.MMWR 57(53):Q1-4.
AAP, Committee on Infectious Diseases (2006). Varicella-Zoster Infections. In: LK Pickering (Ed.), Red Book: Report of the Committee on Infectious Diseases (27th ed., pp. 711-25). Elk Grove Village, IL.
CDC (2006). General recommendations on immunization: recommendations of the Advisroy Committee on Immuniazation Practices (ACIP). MMWR 55(RR15);1-48.