Somewhere around the middle of pregnancy, a new line item shows up on your to-do list: vaccines. And it can feel like a strange ask. You've spent months being told to be careful about what goes into your body — and now someone wants to give you three shots. It's a fair thing to pause on.
Here's the reassuring logic underneath it. The vaccines recommended in pregnancy aren't really for the next nine months. They're for your baby's first few months of life — the window when a newborn is most vulnerable to a handful of infections and least able to fight them off. You are, quite literally, the delivery system.
This guide walks through the three on the list — Tdap, flu, and RSV — why each is recommended, when to get it, and the one real decision you get to make (maternal RSV vaccine versus infant nirsevimab).
The big idea: you lend your baby your immune system
A newborn arrives with an immune system that's present but inexperienced. It hasn't met many germs, can't mount a strong response yet, and can't receive most vaccines for weeks to months. That leaves a gap — and some infections are most dangerous precisely during that gap.
The fix is elegant. When you're vaccinated during pregnancy, your body makes antibodies, and those antibodies cross the placenta to your baby — who is then born already carrying a supply of borrowed protection (doctors call it passive immunity) that holds the line until their own immune system and vaccine schedule catch up. The CDC recommends Tdap, flu, and (seasonally) RSV vaccination in pregnancy for exactly this reason: to "maximize the maternal antibody response and passive antibody transfer to the infant."
It's worth saying plainly: none of these are live vaccines. They can't give you or your baby the disease. What they give is a head start.
Tdap: protecting against whooping cough
What it's for: Tdap protects against pertussis (whooping cough), along with tetanus and diphtheria. Whooping cough is genuinely frightening in newborns — it can cause violent coughing fits, trouble breathing, and pauses in breathing, and babies under two months old are far too young to be vaccinated themselves.
When to get it: Every pregnancy, ideally between 27 and 36 weeks — earlier in that window is better. The CDC and ACOG both recommend Tdap in the third trimester of each pregnancy, because antibody levels peak about two weeks after the shot and then transfer most efficiently to the baby late in pregnancy.
The surprising part: you need it again every time. The antibodies you pass to one baby don't carry over to the next, so Tdap is recommended in every pregnancy regardless of when you last had it. It's also wise for other adults who'll hold your newborn — partners, grandparents — to be up to date, a strategy called "cocooning."
Flu: a shot that protects two people
What it's for: Pregnancy changes your heart, lungs, and immune system in ways that make the flu hitter harder — pregnant people are at higher risk of severe illness and hospitalization from influenza. And babies under six months old are the pediatric age group most likely to be hospitalized with flu, yet they can't be vaccinated until they're six months old.
When to get it: Any trimester, during flu season. The CDC is direct about this: flu vaccination is recommended "during any trimester of pregnancy." One catch — pregnant people should get the flu shot, not the nasal spray (the nasal spray is a live vaccine).
The payoff: the flu shot protects you and gives your baby a buffer. As the CDC puts it, a flu shot in pregnancy "helps to protect babies from flu illness and flu related hospitalizations for the first several months after their birth, when they are too young to get vaccinated." Two people, one shot.
RSV: the newest tool, and a real choice
RSV (respiratory syncytial virus) is the one most parents have heard the least about — and it's a big deal. It's a leading cause of hospitalization in US infants, usually showing up as a bad cold that, in the smallest babies, can turn into serious breathing trouble (bronchiolitis). Until recently there was no way to protect newborns; now there are two, and here's where you get a choice.
Option A — the maternal RSV vaccine (you get the shot). A single dose of the maternal RSV vaccine (brand name Abrysvo) given at 32–36 weeks of pregnancy prompts you to make antibodies that cross to your baby, per the CDC and ACOG. There's a timing wrinkle: it's recommended when that 32–36 week window falls during RSV season — roughly September through January in most of the US — so the antibodies are highest right when RSV is circulating. It protects your baby for about the first 6 months of life.
Option B — nirsevimab (your baby gets the shot). Nirsevimab is a long-acting monoclonal antibody given directly to the baby — not a vaccine that teaches the immune system, but a dose of ready-made antibodies that goes to work immediately. It's recommended for babies whose mothers didn't get the maternal RSV vaccine (or didn't get it at least two weeks before delivery), given shortly before or during RSV season, or within a week of birth for babies born during the season.
Which one? The headline from the CDC is reassuring: most babies need only one, not both. If the maternal vaccine lines up with your due date and RSV season, that single shot can cover your baby. If the timing doesn't work — your baby is due in spring, or you deliver before the vaccine had time to work — nirsevimab fills the gap. Your OB and your baby's pediatrician will map this to your due date, and ACOG laid out the latest thinking in its 2025 maternal immunization update. There's no wrong answer here — both routes get your baby protected.
"Is all of this actually safe?"
Short version: yes, and these recommendations come from the organizations whose entire job is weighing benefit against risk. Tdap and the inactivated flu shot have been given to pregnant people for many years with extensive safety monitoring. The maternal RSV vaccine was studied in large clinical trials before it was approved and recommended. And because none of the three are live vaccines, they cannot cause the infection in you or your baby.
The most common side effects are the ordinary ones: a sore arm, maybe feeling a bit run-down for a day. Compared with what whooping cough, flu, or RSV can do to a newborn, that's a trade most parents are glad to make. If you have a specific medical history or concern, that's exactly the conversation to have with your OB or midwife.
How to fit it into your prenatal calendar
You don't have to engineer the timing yourself — your prenatal care is built for this. A rough map:
- Flu — at any prenatal visit during flu season.
- Tdap — at a visit between 27 and 36 weeks, every pregnancy.
- RSV (maternal vaccine) — at a visit between 32 and 36 weeks, if that falls in RSV season; otherwise plan for your baby to get nirsevimab.
It's safe to get more than one of these at the same appointment, so you may knock out two in one sitting. If you lose track of what you're due for — pregnancy brain is real — just ask at your next visit. For the broader picture of your baby's own shots after birth, see our guide to the childhood vaccine schedule, explained.
The bottom line
The vaccines recommended in pregnancy — Tdap, flu, and RSV — are a way to hand your newborn protection they can't yet make for themselves, covering the exact months when whooping cough, flu, and RSV are most dangerous and your baby is least defended. Tdap and flu are long-established and recommended for every pregnancy and every flu season. RSV is the newest tool, with a genuine choice between the maternal vaccine and infant nirsevimab — and for most families, one of the two is all it takes. Bring your questions to your OB; this is one of the clearest, best-studied ways to start your baby's life a step ahead.
This article is educational and not medical advice. Always check with your pediatrician/provider.