The Respiratory Syncytial Virus (RSV) is a common respiratory pathogen that typically causes mild, cold-like symptoms in healthy adults. However, for vulnerable groups, including infants and older adults, an RSV infection can lead to severe lower respiratory tract disease requiring hospitalization. Since infants under six months old face the highest risk of severe illness, a maternal infection during pregnancy is a significant concern. The worry centers on how the mother’s illness might indirectly affect the developing fetus and the heightened vulnerability of the newborn.
Understanding RSV Symptoms and Severity
RSV symptoms in a pregnant adult often begin subtly, mimicking a severe cold or influenza with a congested or runny nose, a dry cough, sore throat, and a low-grade fever. Within a few days, the infection can progress, leading to more concerning symptoms such as wheezing and a severe, persistent cough. The progression to a lower respiratory tract infection like pneumonia or bronchiolitis makes RSV potentially serious for a pregnant person.
The physiological changes of pregnancy can increase the severity of respiratory illnesses. As the uterus expands, the diaphragm is displaced upward, which reduces the functional residual capacity of the lungs by 10 to 20%. This mechanical change, coupled with a higher oxygen demand and an altered immune response, can make it harder for the body to manage a severe respiratory infection. A severe infection can lead to complications such as respiratory failure, which may necessitate hospitalization.
A pregnant person should seek immediate medical attention if they experience difficulty breathing, rapid or shallow breathing patterns, persistent chest pain, or a high fever that does not respond to safe fever reducers. Uncontrolled respiratory distress or a prolonged high fever can stress both the mother and the fetus. If symptoms like a bluish tint to the lips or nail beds, known as cyanosis, appear, emergency care is warranted as this indicates a lack of oxygen.
Potential Impact on Fetal Development and Neonatal Health
The most direct risk to the fetus from maternal RSV infection is low, as the virus is not known to commonly cross the placenta. The greater and more established risk comes from the mother’s systemic illness and the complications that severe respiratory infection can trigger. Severe maternal illness from RSV has been associated with an increased chance of adverse birth outcomes.
One of the primary concerns is an increased risk of preterm labor and birth, defined as delivery before 37 weeks of gestation. Studies indicate that pregnant individuals with an RSV infection may have a higher likelihood of delivering early compared to those without the virus. The intense physical stress, inflammation, and fever associated with a severe maternal infection are thought to be the main mechanisms that can precipitate early contractions.
Beyond preterm birth, a maternal RSV infection has also been linked to other negative consequences, including low birth weight. Low birth weight is often a result of either preterm birth or restricted fetal growth. Even if the virus itself does not directly harm the developing fetus, the mother’s compromised health can disrupt the optimal environment for fetal growth and well-being.
The vulnerability of the newborn who contracts RSV after birth is also a major factor, with infants under six months being the most susceptible to severe illness. If a pregnant person contracts RSV close to their due date, there is an elevated risk of transmitting the virus to the newborn shortly after delivery. Because the infant’s immune system is immature, a postnatal RSV infection can quickly lead to bronchiolitis or pneumonia.
Protective Measures and Management Strategies
The most effective strategy for managing RSV risk during pregnancy involves a combination of prevention and supportive care. Basic hygiene measures are the first line of defense, including frequent handwashing with soap and water, avoiding touching the face, and steering clear of individuals known to be sick. These simple actions can significantly reduce the chance of catching the highly contagious virus, which spreads through respiratory droplets and contaminated surfaces.
A significant protective measure is the maternal RSV vaccine, which is recommended for administration during the third trimester of pregnancy to protect the newborn. The vaccine is typically given between 32 and 36 weeks of gestation, usually during the seasonal period from September through January. This timing is intended to maximize the transfer of protective antibodies across the placenta to the fetus before birth.
The antibodies passed from the mother provide the newborn with passive immunity, offering protection against severe RSV disease for approximately the first six months of life, when infants are most at risk. If a pregnant person misses the vaccine or is nearing their due date outside of the recommended window, the baby may instead be eligible for a long-acting monoclonal antibody injection soon after birth, which provides immediate protection.
For a pregnant person who develops an RSV infection, treatment focuses primarily on supportive care. This includes getting plenty of rest, maintaining hydration, and using acetaminophen to manage fever and discomfort. Antiviral medications are generally not used to treat RSV in healthy adults. Any pregnant individual with suspected RSV should consult their obstetrics provider immediately.