Vaccines During Pregnancy: What's Safe and When

Pregnancy comes with a long list of things to check, and vaccines often sit near the top of it. It can feel contradictory: you are told to be careful with soft cheese and hair dye, and then you are offered four shots in nine months.

Here is the reassuring part. The vaccines routinely offered in pregnancy have been given to millions of pregnant people, and they do something almost nothing else can — they pass protection to your baby for the first months of life, before your baby is old enough for their own vaccines. This guide covers which vaccines are recommended, the weeks to aim for, which ones are usually postponed, and what to do if you have already had one and are now worried.

Why vaccines matter more when you are pregnant

Two things change once you are pregnant. First, your immune system, heart and lungs are all working differently, which is why infections like flu and COVID-19 tend to hit harder in pregnancy. Pregnant people are more likely than others of the same age to develop pneumonia, to need hospital care, and to give birth early because of a severe respiratory infection.

Second, whatever protection you build gets shared. Antibodies (the proteins your immune system makes to fight a specific infection) cross the placenta to your baby and stay in their bloodstream for months after birth. That borrowed protection matters because of a gap in the schedule: babies cannot have their own flu vaccine until around 6 months, and the whooping cough series usually starts at about 2 months and takes months to complete. Your antibodies bridge that window, which is exactly why some pregnancy vaccines are timed for the third trimester, when transfer across the placenta is most efficient.

Which vaccines are recommended during pregnancy?

Four vaccines are routinely recommended in pregnancy by the American College of Obstetricians and Gynecologists (ACOG): influenza (flu), Tdap, COVID-19 and RSV. None of them are live vaccines, and several can be given at the same visit — usually one in each arm.

The flu shot while pregnant

The flu shot is recommended in any trimester, for anyone who will be pregnant during flu season. The version used is the inactivated (killed-virus) injection or the recombinant one, not the live nasal spray — the nasal spray is a live vaccine and is not used in pregnancy.

On timing: if you can, aim to be vaccinated by the end of October in the northern hemisphere, since flu season typically peaks after that. If you are already in your third trimester when the vaccine becomes available, get it as soon as you can rather than waiting. In the United States, current guidance for pregnant people is to use single-dose, thimerosal-free formulations; thimerosal has not been shown to cause harm, so this is a preference about how the vaccine is packaged, not a safety warning about vaccines you have had before.

The benefit runs both ways: fewer severe flu illnesses for you, and antibodies that protect your baby through the months before they can be vaccinated themselves.

Tdap vaccine: which pregnancy weeks?

Tdap protects against tetanus, diphtheria and pertussis (whooping cough). Whooping cough is the reason for the careful timing — it can be genuinely dangerous for very young babies, who often catch it from adults with what seems like an ordinary lingering cough.

In the US, Tdap is recommended in every pregnancy, between 27 and 36 weeks, no matter when you last had it, and preferably early in that window (around 27 to 31 weeks) so your body has time to make antibodies and pass them on. Getting it in each pregnancy is deliberate: antibody levels fall over time, so last pregnancy's dose will not protect this baby as well.

Schedules differ by country, and both are evidence-based. In the UK, the NHS offers the whooping cough vaccine from 16 weeks, usually around 20 weeks, with best protection when it is given before 32 weeks. Follow the schedule your own maternity service uses.

Is the COVID-19 vaccine safe during pregnancy?

The safety data now covers very large numbers of pregnancies, and it has not shown an increased risk of miscarriage, stillbirth, birth defects or preterm birth linked to COVID-19 vaccination. ACOG recommends vaccination in any trimester, partly because pregnancy itself raises the risk of severe COVID-19 illness, and partly because antibodies again reach the baby.

You may run into mixed messaging in the US, and it helps to know why. The CDC now frames the 2025–2026 COVID-19 vaccine as an individual decision made together with your clinician for everyone aged 6 months and older, while still noting that pregnancy increases the risk of severe illness. ACOG has kept its routine recommendation for pregnant people. That is a disagreement about how strongly to word a recommendation, not a new safety signal — and it is a good reason to ask your own provider what they advise for your situation.

RSV vaccine during pregnancy

RSV (respiratory syncytial virus) is the most common reason babies under one are admitted to hospital, usually with bronchiolitis. The maternal RSV vaccine is newer than the others, so here is the detail:

• When: a single dose between 32 weeks 0 days and 36 weeks 6 days, given seasonally — September through January in most of the continental US. In the UK, it is offered around the 28-week appointment and can be given any time up until labour begins.
• How often: in the US, one dose in your first eligible pregnancy; another dose is not currently recommended in later pregnancies.
• The two-week rule: antibodies need roughly 14 days to build and cross the placenta. If your baby arrives within two weeks of your shot — or if you did not have the vaccine — your baby can be offered an RSV antibody injection (such as nirsevimab) instead. Most babies need one route or the other, not both.

Either way, the aim is the same: protection through your baby's first RSV season, roughly their first six months.

At a glance

• Flu — any trimester, every season; the injection, never the nasal spray.
• Tdap — 27 to 36 weeks in every pregnancy, early in that window (NHS: from 16 weeks, usually about 20).
• COVID-19 — any trimester; ask your provider about the current recommendation where you live.
• RSV — 32 to 36 weeks during RSV season (NHS: from 28 weeks), or an antibody injection for your baby after birth.

Which vaccines are usually avoided while pregnant?

The general rule is simple: live vaccines are postponed until after birth. These contain a weakened form of a virus or bacterium, and the concern is theoretical rather than something that has been observed — but since there is usually no urgency, the standard advice is to wait.

Commonly postponed:

• MMR (measles, mumps and rubella)
• Varicella (chickenpox)
• The live attenuated nasal-spray flu vaccine
• BCG (tuberculosis) and oral typhoid
• Yellow fever — occasionally considered if travel to a high-risk area truly cannot be avoided, with your provider weighing the risks
• HPV — not given in pregnancy; remaining doses are simply completed afterwards

If you are planning a pregnancy, this is worth handling in advance: have MMR or varicella vaccination before you conceive, and wait about four weeks before trying.

If you were vaccinated before you knew you were pregnant, try not to panic. The NHS notes there is no evidence that any live vaccine causes birth defects, and no intervention is needed for someone who received the HPV vaccine while unknowingly pregnant. Tell your provider so it goes in your notes, but this is very rarely a cause for alarm.

Vaccines you may be offered for specific risks

Beyond the routine four, several non-live vaccines can be given in pregnancy when the benefit clearly outweighs the risk. Depending on your health, job or travel plans, your provider may discuss hepatitis A or hepatitis B, pneumococcal, meningococcal, or inactivated polio vaccines. Rabies vaccination after a possible exposure is always given, pregnant or not, because untreated rabies is fatal.

If you are travelling, speak to your provider or a travel clinic well ahead of booking rather than in the week before you fly, since some schedules need several weeks.

One more practical step: ask the people who will be around your newborn — your partner, grandparents, older siblings' caregivers — to be up to date on flu and whooping cough vaccines. Protecting the circle around a baby who is too young to be vaccinated is sometimes called cocooning, and it is genuinely effective. Vaccines are one of several everyday pregnancy safety questions where the answers are clearer than they first seem, alongside how much caffeine is safe and whether any amount of alcohol is okay.

What to expect afterwards — and when to call your provider

Most side effects are mild and short. A sore, heavy or slightly swollen arm is the most common one, sometimes with tiredness, a headache, muscle aches or a low-grade temperature for a day or two. If you have two vaccines in one visit, expect both arms to feel it. Sitting down for about 15 minutes afterwards is sensible — pregnancy already makes some people light-headed.

Fever is worth a little more attention in pregnancy than outside it. Ask your provider in advance what they would like you to take for a temperature and at what point they want to hear from you, rather than reaching for whatever is in the cabinet. Rest, fluids and a cool room help in the meantime.

Seek urgent care if you have:

• Signs of a severe allergic reaction in the minutes to hours after a vaccine: trouble breathing, swelling of the face, lips, tongue or throat, widespread hives, a racing heartbeat, or feeling faint
• A temperature of 38°C (100.4°F) or higher, or a fever that will not settle
• Vaginal bleeding, fluid leaking, or severe or persistent abdominal pain
• A severe headache with vision changes, or sudden swelling of the face and hands
• A noticeable drop in your baby's movements

The last few are pregnancy warning signs generally, not vaccine reactions — they need attention whether or not you have had a shot recently. Alongside vaccination, the ordinary things still help through respiratory season: hand-washing, fresh air indoors, sleep where you can get it, and keeping up safe activity.

Key takeaways

• Flu, Tdap, COVID-19 and RSV vaccines are routinely recommended in pregnancy, and none of them are live vaccines.
• The flu shot can be given in any trimester; the live nasal spray is not used in pregnancy.
• Tdap goes in every pregnancy at 27 to 36 weeks in the US (from about 16 to 20 weeks on the NHS schedule), timed so whooping cough antibodies reach your baby.
• The maternal RSV vaccine is given at 32 to 36 weeks in season; if your baby arrives within two weeks of the dose, they can have an RSV antibody injection instead.
• Live vaccines such as MMR and varicella are postponed until after birth — and if you had one before you knew you were pregnant, tell your provider, but there is no evidence they cause birth defects.
• Schedules differ by country and change over time. Your own provider or midwife has the current version for where you live.

Sources

• ACOG — Maternal Immunizations (Committee Statement)
• CDC — Guidelines for Vaccinating Pregnant Women
• CDC — RSV Immunizations to Protect Infants
• NHS — Vaccinations in pregnancy
• Mayo Clinic — Flu shot in pregnancy: Is it safe?

This article is general information, not a substitute for personalized medical advice. Vaccine recommendations vary by country and are updated regularly. Please talk to your doctor, midwife or another qualified provider about what is right for you and your pregnancy.