Vaccination in Pregnancy: What the Evidence Says

Why Pregnancy Is a Key Window for Immunization

Pregnancy creates a unique immunological opportunity. The placenta actively transports immunoglobulin G (IgG) antibodies from the pregnant person to the fetus, particularly in the third trimester. Vaccines given during this window trigger maternal antibody production that can cross to the baby, providing passive immunity during the months before the infant completes their own primary vaccination series.

This matters because some of the most dangerous infections for newborns — pertussis (whooping cough) and influenza among them — can cause severe complications in babies too young to have been vaccinated themselves. Immunizing during pregnancy is not a new concept; it is an established strategy embedded in U.S. prenatal care guidelines from the CDC and the Advisory Committee on Immunization Practices (ACIP).

For a broader picture of how vaccination fits across the lifespan, see our overview of immunization timelines from infancy to later life.

Vaccines Routinely Recommended During Pregnancy

Tdap (Tetanus, Diphtheria, Pertussis): ACIP recommends Tdap during every pregnancy, ideally between 27 and 36 weeks of gestation. Administering it in each pregnancy — rather than relying on prior vaccination — ensures the highest possible level of anti-pertussis antibodies reach the newborn before delivery. Pertussis is particularly dangerous in infants under two months old, who are too young to have received their own DTaP doses.

Influenza: An inactivated influenza vaccine is recommended for all pregnant individuals during any trimester of flu season. Pregnancy alters immune and cardiopulmonary function in ways that increase the risk of severe influenza complications, including hospitalization. The flu shot also passes antibodies to the newborn.

RSV (RSVpreF): The FDA approved an RSV vaccine for administration at 32–36 weeks of pregnancy to reduce the risk of severe lower respiratory tract disease in newborns and infants up to six months old. Eligibility guidance and seasonal timing recommendations continue to be refined; discuss this option directly with your provider.

COVID-19: The CDC recommends that pregnant individuals remain current with COVID-19 vaccination. Pregnancy is associated with an increased risk of severe COVID-19 illness and adverse pregnancy outcomes, and available safety surveillance has not identified pregnancy-specific concerns with authorized vaccines.

Vaccines Deferred Until After Delivery

Live attenuated vaccines — those that contain a weakened but replicating form of a pathogen — are generally not recommended during pregnancy as a precautionary measure. This category includes the MMR vaccine, the varicella (chickenpox) vaccine, and the combined MMRV vaccine. If a pregnant person is found to be non-immune to rubella or varicella during prenatal screening, vaccination is recommended promptly after delivery.

This deferral should not be misread as evidence that vaccines are broadly unsafe in pregnancy. The recommendation is precautionary and category-specific. Inactivated, subunit, and mRNA vaccines recommended during pregnancy have been evaluated in large safety monitoring systems and carry current approval for prenatal use.

If you have questions about prior immunization history or specific exposures, your prenatal provider or obstetrician is the right resource. Our article on separating vaccine myths from medical evidence addresses common concerns in more detail.

Talking With Your Provider and Staying Informed

Prenatal vaccination decisions should be made collaboratively with a qualified healthcare provider who knows your medical history, current pregnancy details, and local disease patterns. Individual circumstances — including chronic conditions, prior vaccination history, and gestational age — all bear on which vaccines are appropriate and when.

If you have family members who express hesitation about vaccines, evidence-based communication strategies can help. Our piece on talking with hesitant family members about vaccination provides approaches grounded in research.

Finally, the people around a newborn also play a role in protecting them through what public health practitioners call "cocooning" — ensuring that parents, siblings, grandparents, and caregivers are up to date on relevant vaccines, particularly Tdap. Our guide to adult immunization covers what's recommended for the adults in your household.

This article provides general health information and education only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your prenatal care provider or a qualified healthcare professional regarding vaccination decisions during pregnancy.