Prenatal care
Vaccines during pregnancy: Tdap, flu, and RSV explained
May 20, 2026 · 6 min read
Vaccines during pregnancy do double duty: they protect you, and they pass protection to your baby before your baby can be vaccinated. Here is what Tdap, the flu shot, and the maternal RSV vaccine each do, when they are usually given, and which vaccines wait until after delivery. This is education, not medical advice, so always confirm your own plan with your provider.
Why a shot for you protects your newborn
When you get a vaccine during pregnancy, your body makes antibodies, and those antibodies cross the placenta to your baby, mostly in the third trimester. That borrowed protection covers the first months of life, exactly the window when newborns are most vulnerable and too young for most of their own vaccines. It is one of the few ways medicine can protect a baby before birth.
Tdap: one dose, every pregnancy, between 27 and 36 weeks
Tdap protects against tetanus, diphtheria, and pertussis, the whooping cough that is most dangerous for young infants. CDC and ACOG recommend one dose of Tdap during every pregnancy, ideally between 27 and 36 weeks, and earlier in that window helps your body build and transfer more antibodies before delivery (CDC, ACOG). Every pregnancy means every pregnancy: a dose from a previous pregnancy or from years ago does not replace this one, because antibody levels fade and each baby needs fresh protection.
The flu shot: any trimester, during flu season
Influenza tends to hit harder during pregnancy, and it can be serious for newborns too. CDC recommends the flu shot for pregnant women in any trimester, whenever flu season arrives (CDC). It is an inactivated vaccine, meaning it contains no live virus. If you are pregnant during the fall or winter months, the flu shot belongs on your prenatal checklist.
RSV: a newer, seasonal option for protecting your baby
RSV, respiratory syncytial virus, is a common cause of serious lung infections in young infants. There is now a maternal RSV vaccine that can be given between 32 and 36 weeks of pregnancy during its seasonal window, per current CDC guidance, so your baby is born with protection (CDC). Because the timing depends on the season and on your due date, and because there is also an antibody immunization that can be given directly to the baby after birth instead, this is one to discuss case by case: ask your provider about timing and which option fits your family.
What is not given during pregnancy
Live vaccines, such as the measles-mumps-rubella (MMR) vaccine and the chickenpox vaccine, are generally not given during pregnancy as a precaution (CDC). If you are missing one of these, your provider will usually plan it for after delivery, often before you leave the hospital. This is also why a preconception visit is valuable: catching up on live vaccines before pregnancy means you carry that protection into it.
Keep your vaccine record where you can find it
Vaccine timing questions come up at almost every prenatal visit, and the honest answer is often I do not remember. The Mommy Passport, the free patient side of Materna Health Solutions, keeps your pregnancy record, including the vaccines you have received and when, in one place on your phone, in English or Spanish. That way, when your provider asks about Tdap or the flu shot, the answer travels with you, even across clinics or across the border.
Frequently asked questions
- I got Tdap in my last pregnancy. Do I need it again?
- Yes. CDC and ACOG recommend a Tdap dose during every pregnancy, ideally between 27 and 36 weeks, because antibody levels fade over time and each baby needs its own fresh protection. Confirm the exact timing with your provider.
- Can the flu shot give me the flu?
- No. The flu shot given in pregnancy is an inactivated vaccine, so it cannot cause the flu. Some people feel a sore arm or mild tiredness for a day or two, which is the immune system responding, not an infection. Call your provider if anything feels concerning, and call 911 for any emergency.
- What if I am past the recommended window for one of these vaccines?
- Do not guess and do not skip your next appointment over it. Timing recommendations have flexibility, and your provider can tell you what still makes sense for you and your baby, including options given to the baby after birth.