RSV infection during pregnancy: what happens

RSV is so common that most adults catch it every few years without realizing it — it presents as an ordinary cold. During pregnancy, though, expectant parents naturally worry about any illness. This guide covers what RSV infection during pregnancy typically looks like, what risks exist for mom and baby, and what the infection means for your newborn's protection after birth.

RSV in pregnancy: the basics

RSV during pregnancy behaves similarly to RSV outside of pregnancy in most healthy adults — it presents as a cold with runny nose, cough, mild fever, and fatigue, lasting 7–14 days. Pregnant people are not at dramatically elevated risk of severe RSV compared to other healthy adults, though the immune changes of pregnancy mean any respiratory illness can feel worse and recover more slowly.

The concern about RSV in pregnancy centers less on the pregnant person and more on two downstream questions: does the infection harm the developing baby, and does it change how protected your newborn will be?

Does RSV cross the placenta?

RSV does not typically cross the placenta and infect the fetus directly. Unlike some viruses (rubella, cytomegalovirus, Zika), RSV is not considered a transplacental pathogen. The virus stays in the respiratory tract of the infected person. There is no evidence that RSV infection during pregnancy causes birth defects, miscarriage, or fetal harm through direct infection.

Can severe RSV illness during pregnancy cause complications?

In rare cases where RSV progresses to significant lower respiratory illness — pneumonia or bronchiolitis — in a pregnant person, the reduced oxygenation and systemic illness could theoretically affect fetal wellbeing, as can any severe maternal illness. This is uncommon in otherwise healthy pregnant people without underlying lung conditions.

If you develop RSV and are experiencing:

• Significant difficulty breathing
• Oxygen saturation below 95%
• High fever that doesn't respond to acetaminophen
• Decreased fetal movement

Contact your OB or go to labor and delivery for evaluation. Don't manage severe respiratory symptoms at home during pregnancy.

Does getting RSV during pregnancy protect your newborn?

This is the most practically important question. When you get RSV, your immune system produces antibodies against the virus. Some of these antibodies do cross the placenta — the same mechanism that makes the maternal RSV vaccine work.

However, the antibody levels from natural infection are generally lower and less predictable than from the vaccine. The Abrysvo vaccine is specifically formulated to produce a high, consistent antibody response timed to maximize placental transfer at 32–36 weeks. Natural infection produces whatever response your immune system generates, at whatever point in your pregnancy it occurs.

If you get RSV during pregnancy, the protection your newborn receives depends on:

• When in pregnancy you were infected. Infection in the third trimester gives the most time for antibody transfer before birth. First-trimester infection may result in antibodies that wane before your baby is born.
• How robust your immune response was. This varies from person to person.
• Whether you also received Abrysvo. If you had natural RSV infection and separately received the maternal vaccine during your eligible window, the vaccine-induced antibodies add to whatever natural immunity you developed.

If you had RSV during pregnancy: should you still get vaccinated or have your baby get Beyfortus?

Prior RSV infection doesn't automatically disqualify you from the maternal vaccine, and natural infection doesn't guarantee your baby has sufficient protection. Talk with your OB about whether Abrysvo is still indicated given your specific timing, and ask your pediatrician whether Beyfortus is recommended for your newborn after birth.

For most families, the simpler path is: if you didn't receive Abrysvo during pregnancy, make sure Beyfortus is on the schedule for your newborn at the right time.

Reducing RSV exposure during pregnancy

There's no specific recommendation to quarantine during pregnancy, but standard precautions are sensible during RSV season:

• Wash hands frequently, especially before touching your face
• Avoid close contact with people who have obvious cold symptoms
• If you have older children in daycare, be aware that they are a likely route of RSV introduction — hand hygiene at the door when they come home

Not medical advice. This guide is for educational purposes. Always discuss illness during pregnancy with your OB or midwife. In an emergency, call 911 or go to your nearest labor and delivery.