Why Vaccination During Pregnancy Matters
Vaccination during pregnancy serves two distinct purposes: protecting the mother from illness during a period of immune system changes, and providing passive immunity to the newborn through antibody transfer across the placenta.
Newborns cannot receive most vaccines until 2 months of age. In the weeks between birth and their first vaccinations, they are vulnerable to infections that can be severe or fatal — particularly whooping cough (pertussis) and influenza. Maternal vaccination during pregnancy is one of the most effective strategies for protecting newborns during this vulnerable window.
The Centers for Disease Control and Prevention (CDC), the American College of Obstetricians and Gynecologists (ACOG), and the World Health Organization (WHO) all recommend specific vaccines during pregnancy based on extensive safety and efficacy data.
Vaccines Routinely Recommended During Pregnancy
Tdap (Tetanus, Diphtheria, Pertussis)
When: 27–36 weeks of pregnancy, ideally between 27–32 weeks
Why it matters: Pertussis (whooping cough) is highly contagious and can be fatal in newborns. Infants cannot receive the DTaP vaccine until 2 months of age, leaving them unprotected in the critical early weeks. When a pregnant woman receives Tdap, her body produces antibodies that cross the placenta and provide the newborn with protection from birth.
Safety record: Tdap has been recommended in pregnancy since 2012. Studies involving hundreds of thousands of pregnancies have not found increased risks of adverse pregnancy outcomes. A 2019 study published in *JAMA* found no association between Tdap vaccination in pregnancy and adverse neonatal outcomes.
Recommendation: Tdap is recommended in every pregnancy, even if the mother received it in a previous pregnancy or recently. Antibody levels wane, and each pregnancy represents a new opportunity to protect a new newborn.
Influenza (Flu) Vaccine
When: Any trimester, ideally before flu season begins (October in the Northern Hemisphere)
Why it matters: Pregnancy increases the risk of severe influenza complications. Pregnant women are more likely to be hospitalized with flu than non-pregnant women of the same age, due to changes in immune function, heart rate, and lung capacity. Influenza during pregnancy is also associated with preterm birth and low birth weight.
Additionally, flu antibodies cross the placenta, providing newborns with protection during their first months of life before they can be vaccinated.
Safety record: The inactivated influenza vaccine (the injectable form) has been given to pregnant women for decades. Extensive surveillance data from millions of vaccinated pregnant women has not identified safety concerns. The live attenuated influenza vaccine (nasal spray) is not recommended during pregnancy.
Recommendation: Annual flu vaccination is recommended for all pregnant women during flu season, in any trimester.
RSV Vaccine (Abrysvo)
When: 32–36 weeks of pregnancy
Why it matters: Respiratory syncytial virus (RSV) is the leading cause of infant hospitalization in the United States. Infants under 6 months are at highest risk for severe RSV disease. In 2023, the FDA approved Abrysvo (Pfizer's RSV vaccine) specifically for use in pregnancy to protect newborns through maternal antibody transfer.
Safety record: The clinical trial supporting approval (MATISSE trial) enrolled over 7,000 pregnant women. The vaccine demonstrated approximately 57% efficacy against severe RSV lower respiratory tract disease in infants through 6 months of age. A signal of slightly increased preterm birth was observed in the trial, which led to the recommendation to administer the vaccine at 32–36 weeks rather than earlier. The FDA and ACOG consider the benefit-risk profile favorable.
Recommendation: RSV vaccination is recommended for pregnant women at 32–36 weeks of gestation, particularly those delivering during RSV season (fall through spring).
COVID-19 Vaccines During Pregnancy
Recommendation: The CDC and ACOG recommend COVID-19 vaccination for pregnant individuals. Pregnancy is associated with increased risk of severe COVID-19, including ICU admission, preterm birth, and maternal death.
Safety data: Large-scale surveillance studies, including data from the CDC's v-safe pregnancy registry involving tens of thousands of vaccinated pregnant women, have not identified safety signals for adverse pregnancy outcomes. Studies have confirmed that COVID-19 antibodies are transferred to newborns through both placental transfer and breast milk.
Which vaccines: mRNA vaccines (Moderna, Pfizer-BioNTech) are preferred. The updated formulations targeting current circulating variants are recommended.
Vaccines to Avoid During Pregnancy
Live attenuated vaccines are generally contraindicated during pregnancy because of the theoretical risk that the live virus could cross the placenta. These include:
- MMR (measles, mumps, rubella) — avoid during pregnancy; vaccinate postpartum if needed
- Varicella (chickenpox) — avoid during pregnancy; vaccinate postpartum if not immune
- Live attenuated influenza vaccine (nasal spray flu vaccine)
- Yellow fever vaccine — generally avoided unless travel to high-risk areas is unavoidable
- Typhoid live oral vaccine
If you received a live vaccine before knowing you were pregnant, this is generally not a reason for alarm — the theoretical risk has not been demonstrated in practice — but discuss it with your provider.
Addressing Common Concerns
"Will the vaccine harm my baby?"
The inactivated and mRNA vaccines recommended in pregnancy do not contain live virus and cannot cause infection. Extensive safety monitoring across millions of pregnancies has not identified fetal harm from recommended vaccines.
"Do vaccine ingredients cross the placenta?"
The active components of mRNA vaccines (the mRNA itself) are rapidly degraded and do not cross the placenta. The antibodies produced in response to vaccination do cross the placenta — which is precisely the mechanism that protects the newborn.
"Can I wait until after delivery?"
For Tdap and flu vaccines, waiting until after delivery means your newborn will not receive the protective antibodies during their most vulnerable weeks. The timing of vaccination during pregnancy is specifically designed to maximize antibody transfer to the baby.
Talking to Your Provider
If you have questions or concerns about any vaccine during pregnancy, your obstetrician or midwife is the best resource. They can review your specific health history, current recommendations, and any individual risk factors that might affect the vaccination decision.
You can also find current vaccination schedules and safety information at:
- CDC: cdc.gov/vaccines/pregnancy
- ACOG: acog.org
- WHO: who.int/immunization
*This content is for educational purposes only and does not constitute medical advice. Vaccination decisions during pregnancy should be made in consultation with your healthcare provider based on current guidelines and your individual health circumstances.*
Comments (2)
The breakdown of symptoms was exactly what I needed. Clear, concise, and medically accurate.
The FAQ section at the end was super useful. Answered questions I did not even know I had.