RSV Vaccine in Pregnancy: Side Effects, Timing and Safety

If you are pregnant and wondering whether the RSV vaccine is worth it, the short answer is this: major medical groups recommend one dose of Abrysvo at 32 through 36 weeks of pregnancy for people who did not get an RSV vaccine in an earlier pregnancy. The vaccine makes you produce antibodies that can pass to your baby before birth, and those antibodies help protect your baby in the first months of life. This guide walks through timing, the research, side effects, the preterm birth question and the options, so you can decide with your prenatal clinician.

Is the RSV vaccine in pregnancy worth it?

MotherToBaby, a fact-sheet service that bases its information on published research studies, says major medical groups recommend Abrysvo for women who are 32 to 36 weeks pregnant and have not received the RSV vaccine during a previous pregnancy. MotherToBaby’s Abrysvo fact sheet covers the details. UCLA Health’s FAQ adds that ACOG and SMFM have also strongly endorsed RSV vaccination during pregnancy, in the same way they endorse seasonal flu vaccination.

The benefit figures come from a large trial. UCLA Health reports that among about 7,000 pregnant people randomized to vaccine or placebo between 24 and 36 weeks, Abrysvo reduced severe illness in infants by 81.8% in the first 3 months after birth and by 69.4% within 6 months. In the group vaccinated at 32 to 36 weeks (about 3,000 people), UCLA says the benefit was not significantly different from the wider group, and severe illness fell by 91% within 3 months.

Real-world reports point the same way. Texas Health’s article on RSV vaccination in pregnancy says that in the vaccine’s first year, hospitalization fell 68% in infants under 3 months and 57% in infants under 6 months. Kaiser Permanente’s January 2026 article reports an estimated 50% drop in child RSV hospitalizations at its Northern California hospitals last year, which it credits to prenatal and infant immunizations together, not to the maternal vaccine alone.

How does the RSV vaccine protect a baby, and how long does it take?

The vaccine causes you to make antibodies against RSV. When it is given at the recommended time, those antibodies can pass to the fetus. MotherToBaby says it takes about 2 weeks after vaccination for antibodies to fully pass to the fetus, and that they help protect the baby from severe RSV for about 6 months after birth. UCLA Health makes the same point: your body needs at least 2 weeks to respond, so getting the vaccine earlier in the 32 to 36 week window is ideal.

When in pregnancy do you get the RSV vaccine?

As of October 2026, the CDC’s RSV vaccine safety page says Abrysvo is approved for pregnant women at 32 through 36 weeks of gestation to protect their babies from lower respiratory tract disease caused by RSV. UCLA Health explains that 36 completed weeks means you can receive the vaccine up until the first day of your 37th week.

The timing can vary. MotherToBaby notes that the recommended timing can vary based on RSV activity and guidance in your area. Texas Health describes the recommended window as mothers delivering from September through January, and Kaiser describes it as the fall and winter through January. If you are already past 36 weeks, the vaccine window has closed for you, so ask your clinician what protection your baby can get after birth.

When did RSV vaccination in pregnancy start?

UCLA Health reports that the FDA approved Abrysvo for use in pregnant people on August 21, 2023, to protect newborns and infants against severe RSV disease in the first 6 months after birth. A few weeks later, on September 22, 2023, the CDC’s Advisory Committee on Immunization Practices voted to recommend a single dose for people who are 32 through 36 completed weeks pregnant. The CDC’s safety page confirms that Pfizer’s Abrysvo is the only RSV vaccine approved and recommended for use in pregnant women.

Is Abrysvo a live vaccine?

No. MotherToBaby says Abrysvo is a protein subunit vaccine and does not contain a live virus that can cause RSV. UCLA Health adds that it uses a lab-made version of the protein RSV needs to enter cells, the same basic method used for hepatitis B, pneumonia and meningococcal vaccines.

Can vaccines affect pregnancy or an unborn baby?

Here is what the research on Abrysvo in pregnancy reports, according to MotherToBaby. Studies on the vaccine in pregnancy have not found a higher chance of birth defects. Studies have not found an increased chance of most pregnancy-related problems, such as low birth weight. Studies have not been done to see whether the vaccine increases the chance of miscarriage, and MotherToBaby notes the vaccine is given in the third trimester, after the window when miscarriage can happen. Studies have also not been done on whether it affects a child’s future behavior or learning.

The CDC adds that a preliminary Vaccine Safety Datalink study of the first season of use found that vaccination at 32 to 36 weeks was not associated with an increased risk of preterm birth or of babies born small for their gestational age.

What is the controversy with the RSV vaccine?

Most of the debate centers on preterm birth and on how safety data was weighed before approval. When FDA’s advisers reviewed the vaccine before approval, CIDRAP reported that their efficacy vote was unanimous, but their safety vote passed 10 to 4. Several members said more data were needed on preterm birth, and they raised unanswered questions about giving the vaccine together with other vaccines during pregnancy. GSK, a different manufacturer, stopped its RSV trials in pregnant women in February 2022 to analyze safety data, as CIDRAP also reports.

The CDC recommends either a maternal RSV vaccine or an RSV antibody for the baby, and says most babies do not need both.

Some questions are still open. The CDC says additional studies are looking more closely at the potential risk for high blood pressure problems, including pre-eclampsia, and at preterm birth. Long-term effects on children are not established, and MotherToBaby notes no studies have looked at breastfeeding women directly.

Is there a new warning, and who should avoid the RSV vaccine?

The warnings people see most often belong to different groups. The preterm birth language is in the pregnancy label, and it is why FDA approved Abrysvo only at 32 to 36 weeks. The CDC says the approval was meant to avoid the potential risk of preterm birth before 32 weeks. The Guillain-Barré syndrome findings the CDC describes apply to adults ages 60 and older who received GSK or Pfizer RSV vaccines, not to pregnancy. For infant antibodies, the CDC notes that in February 2024 FDA updated the nirsevimab label to share that cases of serious hypersensitivity reactions, such as hives and fast breathing, have been reported after approval.

Abrysvo is not for everyone who is pregnant. MotherToBaby says people who received an RSV vaccine in a previous pregnancy are not recommended to get one again in a current pregnancy. Arexvy and mResvia are not approved for use in pregnancy, and the CDC says they are not recommended for pregnant women. Ask your clinician whether any allergy history you have changes your decision.

Does the RSV vaccine raise the risk of preterm birth?

This is the most discussed question, so here are the numbers and how each source frames them. UCLA Health reports a small imbalance in the pregnancy trial: preterm birth occurred in 5.7% of vaccinated people and 4.7% of placebo recipients. UCLA says this imbalance was seen only in trial participants living in lower-to-middle-income countries, and that it was not thought to be clinically significant. CIDRAP reports the same 5.7% and 4.7% figures, notes the increase was not statistically significant, and says the preterm births occurred late in gestation.

The CDC says that while the increase was not statistically significant, FDA set the 32 to 36 week window to avoid the potential risk of preterm birth before 32 weeks. UCLA Health says the available data are insufficient to establish a cause-and-effect relationship between preterm birth and Abrysvo. Texas Health reports that the risk of preterm birth once thought to be associated with RSV vaccination is much lower than initially anticipated, around 1%, as told by an OB-GYN. Your clinician can talk through what this means for your pregnancy.

What are the side effects of the RSV vaccine in pregnancy?

The CDC says the most common side effects reported after RSV immunization are usually mild or moderate. UCLA Health says the side effects seen more often in pregnant people who received Abrysvo were localized rather than body-wide. The table below lists what each source reports.

Severe allergic reactions are rare but can be life threatening. The CDC says to call 911 right away for hives, swelling of the face and throat, difficulty breathing, a fast heartbeat, dizziness or weakness. For general comfort questions during pregnancy, see how can pain be managed during pregnancy.

What are the pros and cons of the RSV vaccine in pregnancy?

Here is the trade-off laid out side by side, using each source’s own figures.

How much does the RSV vaccine cost in pregnancy?

None of the sources here give a current price for Abrysvo or for nirsevimab, and prices and coverage differ by clinic, insurer and pharmacy. Ask your prenatal clinic or pharmacy what the dose costs you, and ask your insurer whether it covers the dose, before your appointment.

What are the options for protecting a baby from RSV?

As of October 2026, the CDC says it recommends one of two options to protect all babies from severe RSV: a maternal RSV vaccine given during pregnancy, or an RSV antibody given to the baby. Most babies do not need both. The table compares the options the sources describe.

The CDC’s list does not include anything other than these two options for babies. If you are considering anything else at home, talk with your clinician before you try it. Nirsevimab is the route for babies whose mothers were not vaccinated in the 32 to 36 week window, and Kaiser says it can still be given to eligible babies in that case.

What about fertility, breastfeeding and a future pregnancy?

MotherToBaby says studies have not been done to see whether the RSV vaccine makes it harder to get pregnant. If you got the vaccine before pregnancy, it recommends no waiting period before trying to conceive. Studies have not been done on the vaccine in breastfeeding women, but MotherToBaby quotes the CDC saying that protein subunit vaccines like Abrysvo pose no risk for breastfeeding women or their infants. For a future pregnancy, people who received an RSV vaccine in an earlier pregnancy are not recommended to get it again, and should talk with their clinician about antibodies for the baby after birth. MotherToBaby also notes that exposures fathers have are unlikely to increase risks to a pregnancy.

Before you talk to your clinic

• Ask which week of pregnancy you are in and whether your area’s RSV timing means now or later.
• Share your allergy history, given the CDC’s allergic reaction guidance.
• Ask about your blood pressure history, since high blood pressure questions are still being studied.
• Ask for the cost of the dose and whether your insurer covers it.
• If you are past the window, ask about nirsevimab for your baby.
• If you are also thinking about herbal products, read herbal supplements in pregnancy and breastfeeding first.

Get emergency care right away for a severe allergic reaction after any vaccine, including the symptoms the CDC lists above.

Sources: CDC RSV vaccine safety; MotherToBaby Abrysvo fact sheet; UCLA Health RSV vaccine FAQ; CIDRAP on FDA advisers and the RSV vaccine; Texas Health RSV vaccination in pregnancy; Kaiser Permanente on RSV vaccination in pregnancy.

By The Nerve & Joint Pain Desk Editorial Team

This article is for general information purposes only and does not constitute medical advice. Consult your doctor or qualified healthcare provider before making changes to your health routine.