Respiratory syncytial virus (RSV) is a respiratory infection that has similar symptoms as a cold. But it can be serious for expectant parents who are more at risk for complications from the virus.
You could have a higher risk of severe RSV while pregnant if you already have a lung disease, like asthma, or if you’ve smoked. In general, people with severe RSV are more likely to be hospitalized. There are also specific complications that can happen if you’re pregnant and get RSV.
A 2022 report found that about 0.9% to 10.7% of 8,126 pregnant people tested positive for RSV. One estimate finds that about 58,000 to 80,000 children younger than 5 years old are hospitalized for RSV each year. Another report found that about 80% of lower respiratory infections in children are due to RSV. By the time they’re 2 years old, about all children will have had RSV. By then, they can be immune to it.
The virus can pass to your infant while you’re still pregnant. You can give it to others, or get it through others, from coughing or sneezing. It can also be spread by touching a contaminated surface. The virus is common especially from fall through spring in the U.S., which is also called “RSV season.”
Mild symptoms of RSV include sneezing, a runny nose, fever, cough, and sore throat, to name a few. More severe RSV can cause symptoms like a hard time breathing, different breathing patterns, changes in breathing speed, and blue or gray skin color. If you have RSV and know the difference between these symptoms, you can tell when to seek emergency medical care.
Most RSV infections in babies and adults aren’t severe, but some can be. Severe RSV can cause life-threatening complications such as pneumonia or sepsis. That’s why it’s so critical to know what RSV is and how you can protect yourself, your baby, and your family from it.
RSV Complications During Pregnancy
RSV can lead to several complications during pregnancy, which is why parents are rightfully concerned about getting the infection themselves, or passing it to their fetus or baby.
Preterm delivery
Evidence shows that having RSV puts you at a higher risk of preterm delivery. This means you could have the baby before 37 weeks. If you get RSV, it also puts you at risk of delivering before 28 weeks, compared to people who didn’t have the virus, according to a 2024 study.
A 2023 report specifically looked at three studies on pregnant people who were positive and negative for the virus. Of those studies, people who had RSV were 3.6 times more likely to have a preterm delivery.
In addition to raising your chances of delivering early, having RSV puts infants born preterm at an even higher risk from the virus. Preterm babies with RSV are three times more likely to die from the virus than babies born at full term. They also have a higher risk of hospitalization, being admitted to an intensive care unit, and a higher rate of respiratory failure.
Researchers in a 2024 study found that babies born before 32 weeks had higher rates of RSV-associated acute lower respiratory infection (ALRI) and hospitalization, compared to infants in general. That risk continued for the first 2 years of life.
Babies born between 32 and 37 weeks had a higher RSV-associated ALRI hospitalization rate than the general infant population in their first 6 months. Infants born preterm made up 25% of all RSV-associated hospitalizations, that same report found.
Preeclampsia
Another complication of having RSV during pregnancy is preeclampsia. This condition causes high blood pressure, as well as high levels of protein in your pee that signal kidney damage or other signs of organ damage. This condition can happen during pregnancy and after birth.
Preeclampsia can affect the growth of your fetus, lead to preterm birth, cause the placenta to split from the uterus wall, and cause other serious issues.
RSV can raise your risk of preeclampsia, because your blood pressure goes up as your body fights the virus. Your risk of blood clots, heart swelling, and heart scarring can also grow if you have RSV.
Preeclampsia is serious, so your doctor will monitor you if you get it. Your care team may put you in the hospital or at home on partial bed rest if you have it. Left untreated, preeclampsia can cause death for the parent or baby.
Sepsis
Sepsis is a rare complication of RSV that can be life-threatening. When your immune system is fighting the RSV infection, it may lead to inflammation in your body that can damage tissue, cause organ failure, or lead to death. Sepsis can also cause blood clots in your blood vessels, which reduces blood flow to your organs that can cause your organs to fail.
Symptoms of sepsis include fever, chills, low body temperature, fast heartbeat, dizziness, peeing less, feeling tired, and more.
If you get sepsis during pregnancy, you’ll stay in the hospital under close watch. You’ll likely take antibiotics and may be given fluids or a blood transfusion. Health care professionals will check your blood pressure and organs as well.
Pneumonia and RSV
RSV is the most common cause of pneumonia, which is inflammation in your lungs. Pneumonia can happen if the virus spreads to your lower respiratory tract.
Pay attention to your RSV symptoms to see if they turn into pneumonia symptoms. Signs of pneumonia include coughing up green or yellow mucus (or blood), shallow breathing, shortness of breath, stabbing chest pain when you breathe or cough, fatigue, nausea, vomiting, and appetite loss.
Similar to pneumonia is bronchiolitis, which is when airways in the lungs swell and fill with mucus, making it hard to breathe. In infants, RSV is the most common cause of bronchiolitis. Bronchiolitis is rare in adults.
Respiratory failure
This happens if there’s not enough oxygen in your body, or there’s too much carbon dioxide. You may feel like you can’t breathe, your skin may get pale, your heart may start pounding faster, or you may start breathing faster. Those are just a few symptoms.
If you have respiratory failure, you'll probably need to be hospitalized so you can go on oxygen or a ventilator. Respiratory failure from RSV is more rare, but it can be fatal.
RSV Vaccine During Pregnancy
In 2023, the FDA approved one RSV vaccine specifically for pregnant people. The RSV shot is sold under the brand name Abrysvo and is made by Pfizer.
A few months before Abrysvo was approved, an RSV vaccine had been approved for older adults under the name Arexvy, which is made by GSK. Arexvy wasn’t approved for use during pregnancy.
The single-dose Abrysvo vaccine can prevent lower respiratory tract diseases such as pneumonia or bronchiolitis caused by RSV in infants from birth through 6 months old.
The CDC has said the Abrysvo RSV shot is safe and effective for use in pregnant people to prevent severe RSV disease in infants from birth through 6 months of age.
Who should get the maternal RSV vaccine?
The CDC recommends that people get an RSV vaccine between 32 and 36 weeks of pregnancy from September through January. When you get the vaccine at least 2 weeks before delivery, your baby will be protected from RSV and shouldn't need an RSV immunization.
An RSV antibody prevention treatment called nirsevimab (Beyfortus) is available for babies under 8 months old who are born during RSV season or going into their first RSV season. The treatment isn’t a vaccine because it directly introduces the antibodies to the baby, while a vaccine helps the body produce its own antibodies. Once Beyfortus is out of the child’s body, they don’t have protection against RSV.
How effective is the RSV vaccine?
The RSV vaccine for pregnant people, Abrysvo, reduced the risk of RSV hospitalization for babies by 57%. It also lowered the risk of babies needing a health care visit during the first 6 months after they were born by 51%, early trials showed. The study was on about 3,600 pregnant people who received the same shot.
People who received the vaccine lowered the risk of their baby being hospitalized with RSV by 68%. The vaccine also lowered the need for a health care visit due to RSV by 57% within 3 months after birth. And the vaccine reduced the risk that babies would be hospitalized for RSV by 57% or have a health care visit for RSV by 51% within 6 months after birth.
Maternal RSV vaccine side effects
According to the CDC, the most common side effects people in clinical trials reported after getting an RSV vaccine were:
- Pain
- Redness
- Swelling where the needle went in
- Headache
- Nausea
- Diarrhea
- Muscle/joint pain
- Fatigue
- Fever
Serious adverse effects, including Guillain-Barré syndrome and other inflammatory neurologic events, were reported after some people got RSV shots during clinical trials.
You may have heard of some issues with the RSV vaccine and preterm birth. Another vaccine candidate made by GSK was tied to preterm birth in a trial that was stopped early.
In one of the trials on the Abrysvo RSV vaccine, 4.2% of people who got the vaccine between 32 and 36 weeks had a preterm birth, compared to 3.7% of pregnant people who got a placebo (non-active vaccine).
The FDA recommends getting the Pfizer RSV vaccine between weeks 32 and 36 of pregnancy to reduce the risk of preterm delivery. Researchers studying the Pfizer maternal RSV vaccine didn’t study its effect on high-risk pregnancies.
Does the RSV vaccine during pregnancy also protect my baby?
Yes, but it depends on when you get the shot. The FDA recommends that you get the vaccine between weeks 32 and 36 of your pregnancy. Once you receive the vaccine, your body will make an antibody to protect your infant from the virus. Your baby will be born with the antibody, so they’ll be protected when they’re at the highest risk.
Takeaways
If you’re pregnant, it’s smart to take steps to prevent yourself from getting RSV. If you get it while pregnant, or your baby has it as an infant, most cases aren’t serious.
But it’s important to know which symptoms are severe for you and your baby. That can help you decide if you should get medical attention. Talk to your doctor about getting the RSV vaccine if you want to try to prevent infection.
RSV and Pregnancy FAQs
Can a pregnant person pass RSV on to their baby?
Yes. Mothers can pass RSV on to their unborn infants, as the virus can pass through the placenta.
Do RSV antibodies pass to the fetus?
Yes. When vaccinated between 32 and 36 weeks as recommended by the FDA, the RSV vaccine antibodies will pass on to the fetus and protection will continue after birth for at least 5 months.
Does an RSV shot cause preterm labor?
There have been some reports that the RSV vaccine causes preterm birth, as a trial on another vaccine was tied to preterm birth (and stopped soon after). The FDA recommends getting the Pfizer RSV vaccine between weeks 32 and 36 of your pregnancy in order to reduce the risk of preterm delivery. In trials on the now-approved maternal RSV vaccine, the researchers didn’t study its effect on high-risk pregnancies. It’s important to know that getting RSV during pregnancy is linked with preterm delivery.
Can I breastfeed if I have RSV?
If you have RSV and you breastfeed, you should keep breastfeeding your baby. If the baby has RSV and you breastfeed, continue doing so because studies have shown it helps the infant recover from the infection faster.
Does RSV cause SIDS?
Some studies show that a baby with RSV may be more prone to sudden infant death syndrome, or SIDS. One report said this is the case especially during the baby’s first 3 months of life. Some experts believe the high risk of both issues around the same time in the baby’s life links the conditions, and that the breathing difficulties from RSV can cause SIDS.
Are breastfed babies more immune to RSV?
Breastfeeding helps babies recover from an RSV infection more quickly, according to studies. Exclusively breastfed babies were less likely to be hospitalized for RSV when their parents breastfed them for more than 4 months. One study showed breastfed infants needed oxygen less when they had RSV if they were breastfed, compared to babies who drank formula.
