Immunization Issues

Vaccines for Pregnant Women

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Updated: June 14, 2007

Ideally, women of child-bearing age should be immunized before becoming pregnant. For example, 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, almost always fatal, is prevented if the mother is immune, 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 recommended for pregnant women. Thus, certain immunizations during pregnancy can enhance the mother’s health, while others can protect the child by means of the mother’s antibodies that remain in the child for the first 6 months of life. (1)

According to the Advisory Committee on Immunization Practices (ACIP), the risk of a developing fetus being harmed by vaccination of the mother during pregnancy is theoretical. (2) Currently, no evidence exists of risk from vaccinating pregnant women with any inactivated viral or bacterial vaccine or toxoid. Live attenuated vaccines, including MMR (measles, mumps, and rubella) and varicella, are more concerning and pregnancy is to be avoided 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 of damage to the fetus in prior studies.

The Centers for Diseases Control and Prevention has published a recommended adult immunization schedule, including for pregnant women. (3)

Vaccines recommended for all susceptible pregnant women

Pregnant women are at a higher risk of serious medical complications from influenza than non-pregnant women. Because of this, CDC recommends that all women who will be pregnant during the influenza season should be immunized with the injectable inactivated vaccine (TIV). One study of influenza vaccination of more than 2,000 pregnant women demonstrated no adverse effects in the fetus from the vaccine. (4) The nasal influenza vaccine should not be given to pregnant women.

Tetanus in newborn infants, once common throughout the Americas, is prevented if the mother is immune to tetanus. 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 vaccine containing pertussis has been licensed for use for women in the child bearing age group, Tdap. Pregnancy is not a contraindication to Tdap immunization. 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 and if the last dose of tetanus toxoid-containing vaccine was more than 10 years previously that they would give preference to their being immunized with Td in preference to Tdap during the second and third trimester.

Vaccines that are contraindicated for pregnant women

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 cases: (2)

• Influenza virus vaccine  (nasal spray)
• Oral poliovirus vaccine (no longer distributed in the US) 
• Measles-containing vaccines 
• Mumps-containing vaccines 
• Rubella-containing vaccines 
• Smallpox (vaccinia) vaccine 
• Typhoid vaccine (Ty21a) 
• Varicella live virus vaccine 
• Yellow-fever vaccine

Varicella 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 affected. Susceptible women who are exposed to varicella (or shingles, which is caused by the same virus) should receive varicella-zoster immune globulin (VZIG) 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 VZIG 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.(1) A pregnant household member is not a contraindication for varicella immunization of a child within that household. (5)

VZV vaccine virus uncommonly has been shown to spread 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 VZV immunization should inform her care provider.

Women should be assessed prenatally for evidence of varicella immunity. Upon completion of pregnancy, women who do not have evidence of varicella immunity should receive the first dose of varicella vaccine before discharge from the healthcare facility. A second dose should be administered 4-8 weeks later.

Measles, mumps and rubella live virus vaccines—usually given together as MMR—should not be administered during pregnancy. Because measles increases the risk for spontaneous abortion or premature delivery, pregnant susceptible women are given immunoglobulin within 6 days of exposure. The mumps virus has not been associated with problems during pregnancy. Wild rubella virus in expectant women often leads to congenital rubella syndrome (CRS) in their 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 health care provider will need to consider together her options. The rubella-susceptible woman should be immunized with MMR in the immediate post-partum period. CDC has followed the outcomes of inadvertent rubella vaccination of pregnant women and no cases of CRS have been detected. (6) 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. (7)

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 is unavoidable and she is going to be at risk of exposure to yellow 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 S. typhi.

Vaccines for pregnant women who are at risk

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 in the first trimester, if possible, to avoid any temporal associations that might occur. (1) Specific recommendations for travel by pregnant women (and others) can be obtained at www.cdc.gov/travel.

• Hepatitis B virus (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 US for everyone under the age of 18 years. 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. Screening for active hepatitis B infection is a “standard of care” because it permits her newborn infant to receive birth doses of both vaccine and hepatitis B immune globulin. (8) 
• Pneumococcal polysaccharide vaccine (PPV23) is indicated for specific medical conditions (such as asplenia, metabolic, renal, cardiac, 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. (9) 
• The risk of rabies far exceeds the theoretical risk from the vaccine, if the expectant mother has been exposed to the disease. (9) 
• Meningococcal vaccine recommendations are the same for pregnant women as for others. (9)
• Pregnant women are at risk of acquiring hepatitis A virus infection if there is someone infected in the household, if they have occupational exposure (such as working in a day care facility) or by traveling to areas where hepatitis A is endemic. Hepatitis A infection during pregnancy can be more severe and has been associated with spontaneous abortion or premature delivery. For pregnant women exposed to hepatitis A virus both immune globulin (“gamma globulin”) and vaccine are recommended. Although formal studies of hepatitis A vaccine in pregnant women have not been performed, it has been used without adverse events being reported. (1) 
• Polio viruses have been eliminated in the US 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. (9) 
• No studies have been published regarding use of anthrax vaccine among pregnant women, although women vaccinated against anthrax earlier in life have subsequently had normal reproductive outcomes. (10) Pregnant women should be vaccinated against anthrax only if the potential benefits of vaccination outweigh the potential risks to the fetus. (11) However, the Advisory Committee for Immunization Practices recommends that pregnant women not be vaccinated against anthrax. (12) However, in the circumstances of an exposure to aerosolized anthrax, the theoretical risks of the vaccine would likely be far less than the risk of disease.

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. (9)

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 postpartum have not been shown to interfere with the immune response of children to vaccine and no child has developed disease secondary to vaccine administered to their mother. (1) Human milk contains antibodies and other factors that may help protect infants against many infectious diseases.

References

1. Gall, SA 2003. Maternal Immunization. Obstetrics and Gynecology Clinics of North America, 30(4):632-636. 

2. CDC (2004). Guidelines for Vaccinating Pregnant Women. Recommendations of the Advisory Committee on Immunization Practices (ACIP). 

3. CDC (2004). Recommended adult immunization schedule. US October 2004-September 2005. MMWR November 19, 2004 /53: Q1-4.

4. CDC (2004). Prevention and control of influenza: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR, 53 (RR-06), 1-40. 

5. AAP, Committee on Infectious Diseases (2003). Varicella-Zoster Infections. In: LK Pickering (Ed.), Red Book: Report of the Committee on Infectious Diseases (26th ed., pp. 672-686). Elk Grove Village, IL.

6. CDC, National Immunization Program (NIP). (2004). Rubella. In Epidemiology and prevention of vaccine-preventable diseases (“The Pink Book”) (8th ed.). Atlanta: Author. 

7. AAP, Committee on Infectious Diseases (2003). Rubella. In: LK Pickering (Ed.), Red Book: Report of the Committee on Infectious Diseases (26th ed., pp. 536-541). Elk Grove Village, IL.

8. CDC, National Immunization Program (NIP). (2004). Hepatitis B. In Epidemiology and prevention of vaccine-preventable diseases (“The Pink Book”) (8th ed.). Atlanta: Author. 

9. American College of Obstetricians and Gynecologists (2003). Immunization during Pregnancy. ACOG Committee Opinion 282.

10. Wiesen AR, Littell CT (2002). Relationship between prepregnancy anthrax vaccination and pregnancy and birth outcomes among US Army women. JAMA, 287:1556-60.

11. CDC (2000). Use of Anthrax Vaccine in the United States: Recommendations of the Advisory Committee on Immunization Practices. MMWR December 15, 2000 / 49(RR15);1-20.

12. CDC (2002). Notice to Readers: Status of U.S. Department of Defense Preliminary Evaluation of the Association of Anthrax Vaccination and Congenital Anomalies. MMWR February 15, 2002 / 51(06);127.