Vaccines and Pregnancy: Safe Immunizations and Timing

When you’re pregnant, every decision feels bigger. Should you eat sushi? Is it safe to dye your hair? What about vaccines? The truth is, getting vaccinated while pregnant isn’t just okay-it’s one of the most powerful ways you can protect your baby before they’re even born.

Why Vaccines Matter During Pregnancy

Your immune system changes during pregnancy. It doesn’t shut down, but it shifts. That makes you more vulnerable to infections like the flu, whooping cough, and COVID-19. And when you get sick, it’s not just you who’s at risk. Your baby is too.

Babies under six months can’t get most vaccines yet. They’re too young. That’s why your body becomes their first line of defense. When you get a vaccine, your immune system makes antibodies. Those antibodies cross the placenta and give your baby protection from day one. Studies show this transfer works well-antibody levels in newborns can be as high as 82% of what’s in your blood.

This isn’t theoretical. In 2021, 96% of pregnant people hospitalized with severe COVID-19 in the U.S. were unvaccinated. Babies born to moms who got the flu shot during pregnancy were 63% less likely to catch the flu in their first six months. And when moms got the Tdap shot, their babies were 78% less likely to get whooping cough-a disease that can be deadly for newborns.

Which Vaccines Are Safe During Pregnancy?

Not all vaccines are created equal. Some are safe. Some are not. Here’s what the CDC, ACOG, and WHO agree on as of 2026:

• Influenza (flu) vaccine - Safe in any trimester. Given as a shot, not the nasal spray. Best when you get it by October, but anytime during flu season (October to May) helps.
• Tdap (tetanus, diphtheria, pertussis) - Recommended between 27 and 36 weeks of pregnancy. Every pregnancy. Even if you got it last time. This one gives your baby the strongest protection against whooping cough.
• COVID-19 mRNA vaccines (Pfizer-BioNTech, Moderna) - Safe at any stage. Updated versions are recommended as they become available. Data shows 89% effectiveness against infection and 96% against hospitalization in pregnant people.
• RSV vaccine (Abrysvo) - Approved in 2023. Given between 32 and 36 weeks during September through January. Reduces severe RSV lung infections in babies by 82% in the first 90 days after birth.

Vaccines to Avoid During Pregnancy

Live vaccines are off-limits while you’re pregnant. These contain weakened versions of the virus, and while they’re safe for most people, the risk to a developing baby isn’t zero.

• MMR (measles, mumps, rubella) - Get this at least 28 days before conception.
• Varicella (chickenpox) - Same rule: wait until after pregnancy.
• Nasal flu vaccine (LAIV) - This is a live vaccine. Stick with the shot.

If you’re unsure whether a vaccine you’ve had in the past was live or inactivated, your provider can check your records. No need to guess.

When to Get Each Vaccine

Timing matters. It’s not just about safety-it’s about maximizing protection for your baby.

Flu shot: Get it as soon as it’s available, usually in late summer. You want protection when flu season peaks between December and February. Even if you get it in January, it still helps.

Tdap: Aim for 27 to 30 weeks. That’s the sweet spot. If you get it at 20 weeks, your baby gets only about 63% of the antibodies they would if you got it at 28 weeks. Wait until after 36 weeks, and you risk not giving them enough time to build up protection.

RSV vaccine: Only given between 32 and 36 weeks, and only during the RSV season (September to January). It’s a one-time shot per pregnancy. No boosters needed unless you’re in a high-risk group with prolonged exposure.

COVID-19 vaccine: Stay up to date with the latest version. If you’re pregnant in early 2026 and the updated vaccine just came out, get it-even if you had a booster last year. Immunity fades, and new variants emerge.

What About Breastfeeding?

You can get all the same vaccines while breastfeeding. None of them affect your milk supply or harm your baby. In fact, some antibodies pass into breast milk, giving your baby extra protection. The flu shot, Tdap, RSV vaccine, and COVID-19 vaccines are all safe and recommended while nursing.

Side Effects and Safety

The most common side effects? Sore arm. Maybe a headache. A little fatigue. That’s it.

Over 1.5 million pregnant people in the U.S. have gotten the flu shot since 2010. More than 1.2 million got Tdap. The CDC tracked them all. No link to miscarriage, preterm birth, or birth defects. The same goes for the mRNA COVID-19 vaccines-over 139,000 pregnant people enrolled in the v-safe registry. 84.6% had no pregnancy complications.

A 2023 survey of 2,500 pregnant people found that 78% got at least one recommended vaccine. The biggest reason people hesitated? Fear of harming the baby. But when they talked to their provider, 92% changed their mind.

What If You Missed the Window?

If you didn’t get Tdap between 27 and 36 weeks? Get it right after delivery. You’ll still protect yourself from passing whooping cough to your newborn. But you won’t give your baby the same level of protection in the first weeks of life.

Same with the flu shot-if you didn’t get it before delivery, get it right after. You’ll reduce your chance of getting sick and passing it to your baby.

The RSV vaccine? If you missed the 32-36 week window, you can’t get it after birth. That’s why timing is so important.

What’s Next?

The future of pregnancy vaccines is promising. A vaccine for Group B Streptococcus (GBS) is in late-stage trials. GBS causes deadly infections in newborns. If approved, it could be given between 24 and 34 weeks-similar to RSV and Tdap.

A universal flu vaccine is also in development. Current flu shots need to be updated every year because the virus changes. A universal version could protect against all strains, even new ones, and might be given just once per pregnancy.

The goal? To get 70% of pregnant people worldwide protected by 2030. Right now, coverage in the U.S. is around 60% for Tdap and 59% for flu. In low-income countries, it’s under 25%.

What to Do Now

If you’re pregnant or planning to be:

1. Ask your provider about all recommended vaccines at your first prenatal visit.
2. Write down the dates you need each shot. Set phone reminders.
3. Don’t wait until your last appointment. Vaccines work best when given on time.
4. If you’re unsure about a vaccine, ask for the data. You’re not being difficult-you’re being responsible.

Getting vaccinated during pregnancy isn’t about risk. It’s about reducing risk-for you, and for your baby. It’s one of the few times in parenting where you can act before your child is born to keep them safe. And it’s one of the most effective things you can do.