Respiratory Syncytial Virus (RSV) is a common respiratory virus that typically causes mild, cold-like symptoms in healthy adults. However, for specific populations, including infants and pregnant individuals, the infection can lead to more serious health outcomes. RSV is a highly contagious virus that spreads through respiratory droplets and can also survive on surfaces for hours. Understanding the interaction between RSV and the physiological changes of pregnancy is important, as medical science now offers specific strategies to mitigate the risks associated with this common seasonal infection.
How Pregnancy Alters RSV Severity
Pregnancy leads to several physiological changes that can make a person more susceptible to severe respiratory infections. The immune system undergoes modifications to prevent rejection of the fetus, which results in a state of relative immune suppression. This alteration in the body’s defenses means that a pregnant person may be less effective at fighting off viruses like RSV.
Physical changes also contribute significantly to increased vulnerability to respiratory illness. The growing uterus pushes against the diaphragm, which decreases overall lung capacity and tidal volume. This mechanical restriction, combined with an increased demand for oxygen, means the body has less respiratory reserve to cope with a viral infection. Consequently, a simple infection can more easily progress to involve the lower respiratory tract, leading to conditions like bronchitis or pneumonia.
Symptoms of RSV in a pregnant person often start like a common cold, including cough, congestion, and fever. However, the heightened risk lies in the infection progressing to a lower respiratory tract disease. Pregnant individuals hospitalized with RSV frequently present with severe diagnoses, such as pneumonia, and in some cases, respiratory failure. These severe outcomes are likely due to the combined effects of reduced cell-mediated immunity and decreased mechanical lung function.
Risks to Fetal and Newborn Health
While the primary concern is the pregnant person’s well-being, severe maternal illness can pose indirect risks to the developing fetus. Direct vertical transmission across the placenta is considered rare. The main dangers arise when the parent becomes significantly ill, which can create a hostile environment for the fetus.
Severe maternal infection, characterized by high fever or hypoxemia (low oxygen levels), can trigger fetal distress. Sustained high fever or severe respiratory symptoms compromise the amount of oxygen reaching the placenta. An infection that requires a hospital stay or intensive care unit admission can create stress on the entire system.
A significant risk associated with severe maternal respiratory infection is the increased likelihood of adverse pregnancy outcomes, including premature birth and low birth weight. Severe infections during the third trimester, in particular, have been associated with a higher incidence of prematurity. While the virus itself may not cross the placenta, the severe systemic stress caused by the infection is believed to be the driving factor behind these complications.
The most prevalent risk is the transmission of the virus to the baby after birth. This is a major concern because infants have small airways and an underdeveloped immune system. RSV is the leading cause of hospitalization for infants under six months of age, often leading to severe lower respiratory tract illnesses like bronchiolitis. If the pregnant person contracts RSV near the time of delivery, there is a higher chance of passing the virus to the newborn.
Essential Prevention Strategies
The most effective strategy for an expectant parent to protect their baby from severe RSV is through vaccination. The maternal RSV vaccine (Abrysvo) is designed to prevent severe RSV disease in infants. This vaccine is typically recommended for administration between 32 and 36 weeks of gestation.
The vaccine works by stimulating the pregnant person’s immune system to produce antibodies against the virus. These antibodies then cross the placenta into the fetus, a process known as transplacental transfer. This passive immunity provides protection to the newborn immediately after birth, when they are at the highest risk for severe infection. The maternal vaccine can reduce a baby’s risk of being hospitalized with RSV by over 50% in the first six months of life.
For the vaccine to be most effective, it is often administered during the typical RSV season, which runs from September through January in most of the continental United States. Data suggests that getting the vaccination earlier in the 32-to-36-week window, allowing for at least five weeks between vaccination and delivery, provides the most efficient antibody transfer. Standard hygiene practices also remain important; frequent handwashing, avoiding close contact with individuals who are sick, and cleaning frequently touched surfaces.
Managing RSV Infection While Pregnant
If a pregnant person suspects they have contracted RSV, management focuses on supportive care to ease symptoms and prevent the infection from worsening. Rest and sufficient hydration are foundational to recovery, just as with any viral illness. Fever management is also important to mitigate risks to the fetus, and acetaminophen is generally considered a safe option for reducing fever during pregnancy.
Consult a healthcare provider, such as an OB-GYN or midwife, before taking any over-the-counter medications to ensure they are safe for the current stage of pregnancy. While most cases of RSV are mild and resolve on their own, certain “red flags” signal the need for immediate medical attention. These severe signs include difficulty breathing, persistent wheezing, chest pain, or an inability to keep fluids down. Any indication of reduced fetal movement should also prompt an immediate call to the healthcare provider.