Neutrophils at the Maternal-Fetal Interface: Agents of Protection or Destruction?

Neutrophils, traditionally recognized for their role in innate immunity, have emerged as a key cell population at the maternal-fetal interface, during both uncomplicated and pathological pregnancies. Neutrophil effector functions, including phagocytosis, neutrophil extracellular trap formation, and degranulation, can play protective roles, such as preventing infection and facilitating tissue remodeling during pregnancy. However, these effector functions may also contribute to excessive inflammation, tissue damage, and adverse pregnancy outcomes in the context of sterile inflammation or maternal infection, underscoring the dual nature of neutrophils at the maternal-fetal interface. In this review, we examine the paradoxical nature of neutrophils at the maternal-fetal interface. Further, the protective and deleterious roles of neutrophils during pregnancy are evaluated in the context of bacterial, viral, and parasitic infections. Insights from this review are anticipated to inform basic and clinical research aimed at identifying neutrophils or neutrophil components as biomarkers and therapeutic targets in obstetric conditions and infectious diseases during pregnancy.