Respiratory Syncytial Virus (RSV) is a common respiratory infection that typically causes mild, cold-like symptoms in healthy adults. RSV can pose a more significant threat during pregnancy, raising understandable concerns about the health of both the expectant mother and the developing fetus. The physiological changes that occur during pregnancy can alter the way the body responds to respiratory viruses, sometimes leading to more severe illness. Understanding the specific risks associated with an RSV infection during this time is important for taking appropriate preventative action.
Assessing the Miscarriage Risk
Current medical evidence does not strongly suggest that RSV infection is a direct, primary cause of miscarriage. Miscarriage is defined as a pregnancy loss occurring before 20 weeks of gestation, and research has not established a clear link between a positive RSV test and an increased rate of loss. Studies comparing pregnant individuals who tested positive for RSV with those who did not have found similar odds of miscarriage. This finding suggests that RSV does not behave like some other viral infections, such as Zika or rubella, which are known to directly cause severe fetal harm or loss.
While a direct connection is not established, any severe systemic infection that causes a high fever or profound illness could theoretically stress a pregnancy. The direct risk of RSV specifically causing first or second-trimester loss is considered low based on available data. Existing analyses offer reassurance that RSV is not strongly associated with this outcome.
RSV Severity During Pregnancy
RSV infection is a concern for pregnant individuals because physiological adaptations during pregnancy increase susceptibility to more severe respiratory illness, particularly in the later trimesters. These changes include a reduction in lung capacity as the uterus expands and alterations to the immune system necessary to tolerate the fetus.
When a pregnant person contracts RSV, this can increase the risk of developing lower respiratory tract complications, such as pneumonia or respiratory failure. Severe illness may require hospitalization, and in rare cases, admission to an intensive care unit for mechanical ventilation. This heightened risk to the mother’s health is the primary concern, as severe maternal illness can create a stressful environment for the pregnancy.
Other Adverse Pregnancy Outcomes
While miscarriage risk is not strongly associated with RSV, severe maternal infection has been linked to other adverse pregnancy outcomes. The most commonly documented complication is an increased risk of preterm birth, defined as delivery before 37 weeks of gestation. Pregnant individuals with RSV infection have a significantly higher chance of delivering early compared to those without the virus.
This increased risk is generally considered a secondary consequence of the severe maternal illness, such as a high fever, inflammation, or oxygen deprivation (hypoxia), rather than direct damage to the fetus by the virus itself. Preterm birth and the associated risk of low birth weight can lead to subsequent complications for the newborn. There is also the potential for vertical transmission, where the virus is passed to the baby, increasing the risk of severe RSV in the newborn, especially if they are born prematurely.
Prevention and Management Strategies
Preventative measures offer the most effective way to protect both the pregnant person and the newborn from severe RSV. Good hygiene practices, such as frequent hand washing and avoiding close contact with people who are sick, are important steps. The most significant advancement in prevention is the availability of the maternal RSV vaccine, such as Pfizer’s Abrysvo.
A single dose of the maternal RSV vaccine is recommended for pregnant individuals, typically between 32 and 36 weeks of gestation, during the recommended seasonal window (September through January in most of the U.S.). This timing ensures that protective antibodies are developed and passed through the placenta to the baby, offering protection against severe RSV disease during the first few months of life.
If a pregnant person contracts RSV, supportive care is the standard management, including rest, hydration, and fever control using medications deemed safe during pregnancy. Any specific antiviral or symptom management plan should be discussed immediately with an obstetrician to ensure the best outcome for both mother and baby.