June 2024

Vaccinations for the Expecting Mother

Written by: Alex Sindledecker, PharmD 

Reviewed and Edited by: Rachel Dragovich, PharmD, BCPS, CLC

While vaccines are important in the general population for the prevention of infection, they become even more critical in pregnancy for protection of both mother and baby. Vaccinations received during pregnancy provide immunity in a two-pronged approach – on one hand you are protecting your own body, which is currently nurturing and growing your baby. But also, future protection for your baby once they are outside of the womb. This comes about through the transfer of maternal antibodies – which the mother’s immune system creates in response to the vaccine – across the placenta to the fetus. This process begins early in pregnancy, but it becomes much more effective as gestation advances.1 This enhanced antibody transfer is why a couple vaccinations are specifically recommended later in pregnancy (i.e. third trimester) and are designed to protect the developing baby against infection once born. Preparing the baby for life outside of the womb is a large feat, but that cannot happen without the mother staying strong and healthy throughout pregnancy. This is why vaccination is so important both before, during, and after pregnancy. Additionally, other than the hepatitis B vaccine, infants are not able to start routine vaccinations until 2 months of age. Because some vaccines require multiple doses to build proper immunity in children and others cannot be given until 6-12 months, the greatest protection a newborn has against infection comes from the mother's immunity passed onto the child in the womb and through continuous delivery of antibodies via breast milk afterwards. 

For this article specifically we will dive deeper into select vaccines that are recommended during pregnancy. Not all vaccines are created equal though, some are labeled as “live-attenuated”, “inactivated”, or “recombinant”. A general recommendation from the American College of Obstetricians and Gynecologists (ACOG) and Centers for Disease Control and Prevention (CDC) is that the “live-attenuated” vaccines should not be given during pregnancy.2 Theoretically, the live-attenuated vaccinations may allow transfer of the live virus or bacterium across the placenta, causing an infection in the fetus. Again, this is theoretical, but in an abundance of caution pregnant women are only approved to receive inactivated or recombinant vaccines which do not pose that potential risk. For immunizations and other preventative measures you may have questions about, I would direct you to your healthcare provider who will be able to provide a comprehensive evaluation and recommendations that best fit your needs. Now we will begin our journey discussing key vaccinations to be received during pregnancy, first beginning with “Tdap”. The following discussion points can be found summarized in Table 1 at the conclusion of this article.  

Whooping cough, also known as pertussis, is an important immunization to receive during each pregnancy. Pertussis is an infection of the respiratory tract that is highly contagious. Infants are especially vulnerable to developing severe infection. The immunization to prevent this infection in adults is referred to as “Tdap”. Tdap stands for Tetanus, Diphtheria, and Pertussis. According to the CDC, receiving the Tdap vaccine during the 27th – 36th week of pregnancy can reduce rates of pertussis by 78% in those who are younger than 2 months of age.3 This becomes even more important when it is estimated that 7 in 10 deaths from pertussis occur in babies who are younger than 2 months of age.4 Children do not receive their first vaccine that protects against pertussis (DTaP) until 2 months old, and do not complete the series until after one-year of age, therefore receiving their mothers antibodies is crucial. 

Seasonal influenza vaccines are recommended to be received yearly prior to the start of “flu season”, which is generally from October-May. When pregnant, the timing of those recommendations may change depending on the current trimester the mother is in. Getting immunized in July or August can be considered if you are in your third trimester.5 The reason being is that this will likely offer a reduced risk of influenza illness during the first few months after birth for those infants since they will be too young to receive a vaccine themselves. Children are not eligible to be vaccinated against influenza until 6 months old. If the expecting mother is in their first or second trimester during this time, it is recommended to wait until September or October to receive the vaccine.6 When it comes to choosing a vaccine, follow what your health care provider recommends. The American College of Obstetricians and Gynecologists (ACOG) recommends any appropriate inactivated influenza vaccine (IIV) or recombinant influenza vaccine (RIV) to be administered if no other contraindications are present.7 The live attenuated influenza vaccines are contraindicated for use during pregnancy.6 

COVID-19 (novel COronaVirus Disease-2019) infections during pregnancy pose a severe risk of causing serious complications up to and including death. Due to this, both the ACOG and CDC recommend staying current with COVID-19 vaccinations before and during pregnancy.8-9 The vaccination can be given during any trimester of pregnancy.  Children are eligible to receive the COVID-19 vaccine series starting at 6 months of age. Maternal vaccination has been shown to provide adequate protection to those younger than 6 months of age while also being safe as compared to those who are not pregnant.10 

The newest addition to the list of immunizations available and recommended is for the prevention of respiratory syncytial virus (RSV). Respiratory syncytial virus (RSV) is another common respiratory virus that is generally mild in healthy adults. However, severe cases often manifest in the extremes of ages – both our young and older population. Additionally, RSV is the leading cause of infant hospitalizations in the United States.9 The RSV vaccine, ABRYSVO™, is FDA approved for use in pregnant women during weeks 32-36 of gestation.10 The CDC recommends pregnant women receive the vaccine if they are 32-36 weeks gestation during the RSV season of September to January.  Currently there is not an RSV vaccine approved for infants, however some children may be eligible for the RSV antibody if the RSV vaccine was not received during pregnancy. This should be discussed with the child's pediatrician. Additionally, at this time it is unknown whether a repeat dose of the RSV vaccine is needed for each pregnancy, so follow guidance from your health care provider as updates become available. 

As is true for individuals of the general population, vaccination can vastly reduce the severity of illness experienced. This is especially important in our pregnant population as complications of these diseases can have more serious manifestations when compared to the general population. When pregnant, the mother not only has to protect herself, but also has to protect her unborn baby. Immunizations and other forms of preventative medicine can help with this immensely. Receiving the immunizations discussed in this article is a personal choice, however they have the potential to reduce the risks of having a more severe illness compared to those not vaccinated. It is always important to discuss any medical decisions with your health care provider in order to receive the safest and most appropriate advice possible.