Vaccines for pregnant women

In an ideal world, all women of child-bearing age would receive all recommended vaccines before becoming pregnant in order to keep themselves and their unborn children healthy. During pregnancy:

• Rubella (German measles) can cause heart defects, cataracts, intellectual disability or deafness in the infant.
• Tetanus (lockjaw) can cause an often-fatal illness in unvaccinated mothers and newborn infants.
• Influenza has been shown to cause more severe illness in pregnant than in non-pregnant women and often leads to pneumonia, hospitalization and, rarely, death.
• Varicella (chickenpox) can cause severe pneumonia in pregnant women and has caused birth defects in fetuses.

In addition to the direct benefit of preventing birth defects in the fetus and illness in the pregnant woman, there are other reasons why being up-to-date on vaccines is important, especially during pregnancy.

Vaccination protects against infection with bacteria or viruses by stimulating the body’s immune system to produce antibodies, or blood proteins, that in many cases are protective. A newborn baby’s immune system is not mature or developed enough to produce these antibodies in the first few weeks to months of life. Antibodies from the mother are transferred to the fetus while still in the womb. Examples of this “mother’s gift of protection” include antibodies to tetanus, measles, rubella, influenza, and most likely pertussis or whooping cough.

Some infections are less common in newborn infants because they have antibodies from their mothers that prevent these infections. The opposite also is true. Some infections can be more severe in very young infants because their mothers have not passed antibodies to them in the womb (because mothers have not developed antibodies).

Unfortunately, these antibodies transferred from mother to infant are not permanent and gradually are lost as the infant ages. As this happens, the infant’s immune system also is developing so that they can produce antibodies after vaccination. So, vaccinating women of child-bearing age either before or during pregnancy also may protect their newborn infants from severe illness or death from some infections.

There is no evidence that vaccination in pregnancy is harmful to either mother or fetus. The Advisory Committee on Immunization Practices (ACIP) has stated that concerns that vaccinating pregnant women will affect the developing fetus are theoretical. In fact, some vaccines (e.g., tetanus toxoid vaccine and influenza vaccine) have been given to millions of pregnant women without any serious side effects in either mother or fetus. This is especially true when vaccines are given in the second and third trimester of pregnancy (after week 13) because by this point most fetal body organs and systems are fully developed.

Many vaccines contain inactivated (killed) viruses, bacteria or toxoids, and there is no evidence that these pose any risk in pregnancy. There are more concerns that vaccines that contain live attenuated agents—such as measles, mumps, rubella (MMR); varicella; live-attenuated influenza vaccine (LAIV)—may be harmful. As a precaution, it is advised that women do not become pregnant for 28 days after receiving live-attenuated vaccines, even though there has been no evidence that the fetus is damaged as a result of these vaccines.

The Centers for Diseases Control and Prevention (CDC) have published recommendations for immunizing pregnant women. These guidelines list vaccines that are recommended for all women, recommended for women in special medical circumstances and vaccines not recommended in pregnancy.

Vaccination and breastfeeding

Breastfeeding is not a contraindication or precaution to vaccination. On the contrary, antibodies against vaccine preventable diseases have been demonstrated in breastmilk collected from women vaccinated during and after pregnancy. These antibodies may have a role in protecting infants from acquiring diseases in the first few months of life, and research in this area is progressing. Although virus has occasionally been isolated from breastmilk after administration of live, attenuated vaccines, there have been no documented cases of clinical disease in the infants of these mothers.

Future areas of research

Vaccination in pregnancy is an important intervention to prevent illness in mothers and to potentially prevent or lessen the severity of illness in infants during the first weeks to months of life. Examples of vaccines for use in pregnancy that are being studied by investigators associated with The Center for Vaccine Awareness and Research and Baylor College of Medicine include:

• Pertussis (whooping cough)
• Respiratory syncytial virus (RSV), a virus that causes severe lung inflammation and pneumonia in young infants
• Influenza
• Group B streptococcus , a bacterium that causes bloodstream infection and meningitis in infants less than 4 months of age

To learn more about vaccines and pregnancy, visit the CDC's Guidelines for Vaccinating Pregnant Women.