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? If you’re wondering which shots are okay during pregnancy - and which ones to avoid - you’re not alone. The good news is, science has clear answers. Some vaccines aren’t just safe during pregnancy; they’re vaccines during pregnancy that save lives - yours and your baby’s.

Why Get Vaccinated While Pregnant?

Your body changes a lot during pregnancy. Your immune system softens just enough to protect the growing fetus, but that also makes you more vulnerable to infections like the flu, whooping cough, and COVID-19. These aren’t just colds. They can lead to preterm labor, hospitalization, or even death in rare cases. And your baby? Newborns can’t get most vaccines until they’re two months old. That’s a dangerous gap.

Here’s the magic trick: when you get vaccinated while pregnant, your body makes antibodies. Those antibodies cross the placenta and give your baby protection before they’re even born. It’s like handing them a shield they can use in their first fragile months. Studies show these antibodies can reduce the risk of whooping cough in babies under two months by over 90%. For flu, it cuts infection risk by nearly half. And for RSV - the virus that sends thousands of babies to the hospital each year - the new vaccine cuts severe illness by almost 70%.

Which Vaccines Are Safe During Pregnancy?

Not all vaccines are created equal. Some are live, meaning they contain a weakened version of the virus. Those are off-limits during pregnancy because of a tiny, theoretical risk. But the ones you need? They’re inactivated or made with mRNA - no live virus, no risk.

• Influenza (flu) vaccine: Safe anytime during pregnancy. Best given between September and October, before flu season peaks. It’s an injection - not the nasal spray. The nasal spray (LAIV) contains live virus and should be avoided.
• Tdap (tetanus, diphtheria, pertussis): Recommended between 27 and 36 weeks of pregnancy, ideally at 27-30 weeks. This timing gives your baby the highest possible antibody levels. You need it every pregnancy, even if you got it last time. Whooping cough can be deadly for newborns, and this shot is your best defense.
• COVID-19 mRNA vaccines (Pfizer or Moderna): Recommended throughout pregnancy. Updated versions are available as new strains emerge. Data from over 139,000 pregnant people in the CDC’s v-safe registry showed no increased risk of miscarriage, birth defects, or preterm birth. In fact, 96% of pregnant people hospitalized with severe COVID-19 in 2021 were unvaccinated.
• RSV vaccine (Abrysvo): Approved in 2023 and recommended between 32 and 36 weeks during RSV season (September to January). It’s a one-time shot per pregnancy. The MATISSE trial showed it reduced hospitalizations from RSV by 81.8% in babies under 90 days old.

What Vaccines Should You Avoid?

Some vaccines are simply not safe during pregnancy - not because they’ve harmed babies, but because we don’t have enough data to say they’re completely risk-free. These include live vaccines:

• Measles, mumps, rubella (MMR)
• Varicella (chickenpox)
• Nasal flu vaccine (LAIV)
• Yellow fever (unless travel to a high-risk area makes it unavoidable)

If you need any of these, get them at least 28 days before you start trying to conceive. If you find out you’re pregnant and haven’t had them, don’t panic. Talk to your provider. You can get them safely after delivery.

Timing Matters - Here’s the Ideal Schedule

It’s not enough to just get the shots. When you get them makes a difference.

1. Flu shot: Get it as soon as it’s available - usually July or August. You want protection through the peak months of December to February.
2. Tdap: Aim for 27-30 weeks. Getting it before 20 weeks means your baby gets 37% fewer antibodies. After 36 weeks, there’s less time for antibodies to transfer.
3. RSV vaccine: Between 32-36 weeks, and only during September-January. If you’re due in November, get it in October. If you’re due in March, you don’t need it this year.
4. COVID-19 vaccine: Get the latest updated version whenever you’re eligible. No need to wait for a specific week - just get it as soon as possible.

Some providers bundle Tdap and flu shots in the same visit. That’s fine. No increased side effects. No harm to the baby. Just double protection in one poke.

Side Effects? What to Expect

Most people feel nothing. A sore arm. Maybe a headache. A bit of fatigue. That’s it.

According to the CDC’s v-safe registry, 69.8% of pregnant people reported injection site pain after the COVID-19 vaccine. Only 8.7% of those who got the RSV shot reported mild headache or fatigue lasting less than two days. On Reddit, 87% of pregnant users said they got Tdap, and 68% said the only side effect was arm soreness.

Serious reactions? Extremely rare. The rate of anaphylaxis after any vaccine in pregnancy is less than 1 in 100,000. Providers watch you for 15 minutes after the shot just as a precaution. No one has ever died from a recommended vaccine during pregnancy.

What About Breastfeeding?

Yes, you can get all of these vaccines while breastfeeding. In fact, you should. If you didn’t get Tdap or the flu shot during pregnancy, get them right after birth. You’ll pass some antibodies through breast milk, and you’ll protect yourself from bringing germs home to your newborn.

Live vaccines like MMR and varicella are also safe while breastfeeding. The virus doesn’t pass through milk. So if you missed them before pregnancy, you’re covered now.

Why Do So Many People Still Hesitate?

It’s not about science. It’s about fear. A 2023 March of Dimes survey found that 41% of hesitant pregnant people worried about their baby’s health. That’s understandable. But the data doesn’t back it up.

Over 1.5 million pregnant people in the U.S. have received the flu shot since 2010. More than 1.2 million got Tdap. No safety signals. No pattern of harm. Just fewer babies in ICUs.

Dr. Laura E. Riley from Weill Cornell put it simply: “Substantial evidence demonstrates the safety of currently recommended vaccines during pregnancy.” The World Health Organization reviewed 147 studies involving 2.3 million pregnancies and concluded the benefits far outweigh any theoretical risks.

What’s Coming Next?

The future of pregnancy vaccines is bright. In September 2023, the FDA approved the first Group B Streptococcus (GBS) vaccine candidate for Phase III trials. GBS causes deadly infections in newborns - and this shot could prevent it. If it works, it could become routine like Tdap.

Scientists are also working on a universal flu vaccine that might protect against all strains, not just the few predicted each year. Early data shows it could be 85% effective - way better than today’s 40-60%.

And global efforts are pushing for 70% coverage of pregnancy vaccines worldwide by 2030. Right now, only 15-25% of pregnant people in low-income countries get them. That’s a gap that needs closing.

What Should You Do Now?

Don’t wait. Don’t Google it at 2 a.m. Talk to your provider at your next prenatal visit. Ask:

• “Have I received Tdap this pregnancy?”
• “Is it flu season yet? Can I get the shot today?”
• “Am I eligible for the RSV vaccine?”
• “Should I get the updated COVID-19 vaccine?”

Write it down. Schedule it. Bring your partner. This isn’t optional. It’s one of the most powerful things you can do for your baby’s first months of life.

You’re not just protecting yourself. You’re giving your newborn a fighting chance.