RSV in Infants: Prevention Options Every Parent Should Know About

Can you guess the leading cause of infant hospitalizations in the United States? You might think accidents, allergic reactions, or the flu, but the answer is actually respiratory syncytial virus (RSV). Every year, RSV sends 58,000 to 80,000 children under the age of 5 to the hospital.

Having a baby in the fall or winter has always meant that parents need to be extra careful about RSV. Fortunately, in 2023 two new ways to protect infants against this virus became available: a vaccine given to women between 32 and 36 weeks of pregnancy and an antibody (passive immunization) that is given directly to babies after birth. Today, we’re covering some of the most common questions we get at MotherToBaby about RSV prevention.

Q: What is the maternal RSV vaccine? When is it given?

The maternal RSV vaccine (brand name Abrysvo®) is a protein subunit vaccine (it contains proteins the body needs to make antibodies against RSV). The vaccine does not contain live virus that can cause RSV. When a woman gets the RSV vaccine during pregnancy, the antibodies she makes can also pass to the developing fetus. These antibodies can help protect the baby from RSV during the first 6 months of life.

The Abrysvo® RSV vaccine can be given to women who are 32 to 36 weeks pregnant who have not received a maternal RSV vaccine in a previous pregnancy. The RSV vaccine is only recommended for use during pregnancy between September and January in most of the United States. 

Q. What is an infant RSV antibody? When is it given?

Infant antibodies, also called passive immunizations, are another effective way to help protect babies from RSV. Two RSV antibodies are currently available: nirsevimab (Beyfortus®) and clesrovimab (Enflonsia®). The RSV antibody is recommended for infants younger than 8 months who are entering their first RSV season if their mothers did not receive the maternal RSV vaccine during pregnancy. Infants and children ages 8 to 19 months who are at high risk for severe RSV illness and entering their second RSV season may also be eligible for the antibody. The RSV antibody is available between October and March for most of the United States and starts working immediately after it is given.

For more information about timing, eligibility, and benefits of infant RSV antibodies, talk with your child’s pediatrician.

Q: Is one of these options better than the other?

Patients can choose either the maternal vaccine or the infant antibody. Both are great options for protecting infants against RSV, and there is currently no preference for one over the other. A slight benefit of getting the RSV vaccine during pregnancy is that most babies will be born with immediate protection if the vaccine is given at least 2 weeks before delivery. Some parents might also prefer the maternal vaccine because it avoids an extra injection (shot) for the baby.

Q. How do we know the RSV vaccine is ok to get in pregnancy?

Studies on the Abrysvo® RSV vaccine have not found a higher chance of birth defects. It’s also reassuring to note that the vaccine is given in the third trimester (between 32 and 36 weeks), which is past the critical period when most birth defects could happen.

Early clinical trials on the vaccine observed slightly more preterm births in women who received the Abrysvo® RSV vaccine than in those who did not (5.7% in the vaccinated group vs. 4.7% in the placebo group). However, newer data from larger studies has not found a higher chance of preterm birth following RSV vaccination in pregnancy. Check out the MotherToBaby RSV vaccine fact sheet for more information on this topic.

Q. If I got an RSV vaccine in my last pregnancy, do I need to get it again in my next pregnancy?

The simple answer is no. At this time, the maternal RSV vaccine is only recommended for women who have not gotten it in a previous pregnancy. Researchers need time to determine if getting the vaccine once can provide ongoing protection for future pregnancies, or if a booster dose is needed in every pregnancy.

If you received the RSV vaccine during a previous pregnancy and are pregnant again, your baby can get an infant RSV antibody to help ensure they are protected.

Making Your Choice

No matter whether you decide on the maternal RSV vaccine or an infant RSV antibody, you’re making a great choice to protect your baby from RSV! Still have questions? Remember that MotherToBaby can be reached by chat, text, phone, or email with questions about the RSV vaccine or any other exposure in pregnancy or while breastfeeding.

RSV in Infants: Prevention Options Every Parent Should Know About

Thinking about pregnancy while also worrying about weight can feel stressful. You are not alone—about 6 in 10 women in the U.S. are overweight or have obesity. Talking about weight can be hard, but it is an important part of planning for a healthy pregnancy.

This blog will explain how weight can affect pregnancy, what GLP-1 medications are, and what we know so far about their use before and during pregnancy.

Why Is Managing Weight Before Pregnancy So Important?

Being overweight or having obesity increases the chance for several pregnancy-related problems, including:

  • Miscarriage
  • Birth defects
  • Preterm delivery (before 37 weeks)
  • Gestational diabetes
  • High blood pressure during pregnancy
  • Stillbirth
  • Cesarean delivery
  • Thromboembolic events (blood clots)

You can read more about obesity and pregnancy in our factsheet here: https://mothertobaby.org/fact-sheets/obesity-pregnancy/

The good news is even a small weight loss—just 5–7% of your body weight—before pregnancy can improve health and pregnancy outcomes. Starting before you get pregnant is best. Some people do this through healthy eating and exercise, while others may need surgery or medication.

What Are GLP-1 Medications?

GLP-1s are medicines that act like a natural hormone in your body. They help control blood sugar, slow down digestion, and make you feel full longer. This can lead to weight loss. Most GLP-1s are given as shots. The best-known ones are liraglutide (Victoza®) and semaglutide (Ozempic®, Wegovy®, Rybelsus®). These are also the ones most studied in pregnancy so far.

Can I Use GLP-1s While Trying to Get Pregnant?

The current product labels recommend stopping GLP-1 medications at least 2 months before pregnancy. The time it takes the body to process medication is not the same for everyone. In healthy non-pregnant women, it can take up to 6 weeks, on average, for most of the GLP-1s to be gone from the body.  

Stopping the medicine can sometimes cause weight gain, which can feel frustrating. Because of this, some people choose to continue until they know they are pregnant. It’s best to talk with your healthcare provider about the risks and benefits for you.

What Do We Know About GLP-1s in Pregnancy?

Here’s what research tells us so far:

  • Studies including over 1,000 women exposed to GLP-1s during the first trimester have not shown an increased chance of birth defects.
  • A study of 168 pregnancies with first-trimester exposure to GLP-1s did not show increased chance of miscarriage, preterm delivery, stillbirth, or SGA infants (small for gestational age-infants whose birth weight is below the 10th percentile for their gestation age).

It’s important to remember that every pregnancy has a baseline risk:

  • Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect
  • 15 to 20 out of every 100 (15-20%) pregnancies end in miscarriage

These typically occur in the first trimester — whether or not medication is used.

At this time, continuing GLP-1s after pregnancy is confirmed is not recommended for two main reasons:

  1. Weight loss during pregnancy is not advised. Losing weight while pregnant may increase the chances of having a baby with SGA, which can lead to complications such as:

    • Low oxygen levels
    • Low Apgar scores (grading system in newborns to define their wellbeing)
    • Meconium aspiration (breathing in the first bowel movement)
    • Hypoglycemia (low blood sugar)
    • Difficulty maintaining body temperature
    • Polycythemia (too many red blood cells)

  1. We lack research on GLP-1s in the second and third trimesters. Without research studies on the use in the second and third trimester, we don’t know if use of GLP-1s could increase the chances of other pregnancy-related problems.

Finding the Path That’s Right for You

Your journey is unique, and there’s no simple answer. That’s why it’s so important to talk with your healthcare provider about the best way to approach weight management before pregnancy.  As Dr. Sarah Obican so masterfully said in a previous Baby Blog post:

“Each of us are beautifully individual” — and our weight loss and pregnancy journeys are beautifully individual, too.

Final Thoughts

Whether you’re already on a weight loss journey or just starting to think about pregnancy, you deserve support and trusted information. We’re here to help you every step of the way.

Factsheets:

Baby Blogs:

Podcasts:

Have questions about a specific medication or concern? Reach out to our MotherToBaby experts by phone, text, email or live chat at MotherToBaby.org.

RSV in Infants: Prevention Options Every Parent Should Know About
January 21, 2026		 page {PAGENO} of {PAGETOTAL}