Respiratory Viruses During Pregnancy: A Growing Threat to Maternal and Child Health
Table of Contents
Pregnancy uniquely alters the immune system, leaving expectant mothers vulnerable to severe complications from respiratory viral infections and potentially impacting the long-term health of their children. A new review, published in Immunological Reviews in January 2026, underscores the complex interplay between maternal immunity, viral infections, and fetal development, highlighting the urgent need for improved preventative measures and a deeper understanding of underlying mechanisms.
The Immunological Shift of Pregnancy
Pregnancy induces significant physiological adaptations to support fetal growth, including substantial changes to the maternal immune system. These changes, while essential for preventing rejection of the fetus, can paradoxically increase susceptibility to severe illness from infections like influenza and respiratory syncytial virus (RSV). As one expert noted, “The immune system is deliberately modulated during pregnancy, creating a window of vulnerability that viruses can exploit.”
Respiratory viral infections during pregnancy pose a dual threat. They can increase maternal morbidity – the severity of illness – and, critically, contribute to long-lasting neurodevelopmental consequences in offspring. Emerging research suggests a link between maternal viral infections and an increased risk of autism spectrum disorder, schizophrenia, and other behavioral conditions, particularly in male children.
The mechanisms driving these adverse outcomes are varied. Some viruses can directly infect reproductive tissues, the placenta, and even the fetus, leading to detrimental pregnancy outcomes. Others, while remaining confined to the respiratory tract, can trigger systemic maternal immune activation (MIA). MIA, even without direct fetal infection, can disrupt fetal brain development.
The Challenge of Maternal Immune Activation
MIA represents a significant challenge in managing respiratory viral infections during pregnancy. While antiviral medications can mitigate severe disease in the mother, they are often insufficient to prevent MIA and its associated adverse effects on the developing fetus. This highlights the critical need for a more nuanced understanding of the immunological processes at play.
Vaccination: A Protective Strategy with Barriers
Maternal vaccination offers a promising avenue for protecting both mother and child from viral diseases. Vaccination boosts the mother’s immune response, providing passive immunity to the fetus through antibody transfer. However, the effectiveness of this strategy is hampered by several factors. Concerns surrounding vaccine and drug safety during pregnancy, coupled with limited access to care and reliable information, contribute to vaccine hesitancy and reduced uptake.
The Role of Progesterone and Future Research
The review emphasizes the importance of understanding the role of hormones, particularly progesterone, in modulating the maternal immune response to respiratory viruses. Research suggests progesterone may influence the severity of infection and its impact on fetal development. Further investigation into these hormonal interactions could reveal novel therapeutic targets.
“Addressing these challenges and advancing mechanistic understanding are essential for improving maternal and fetal outcomes,” the authors conclude. Future research should focus on identifying biomarkers for predicting adverse outcomes, developing targeted therapies to mitigate MIA, and improving access to vaccination and antiviral treatments for pregnant women.
Keywords: RSV; antibody transfer; influenza; maternal immune activation; progesterone.
© 2026 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
