Abstract: The fetal inflammatory response syndrome (FIRS) is a subclinical state in which the fetal immune system is activated. It is a special situation of systemic inflammatory response syndrome (SIRS) in the fetal period. Intrauterine infection and chronic hypoxia are two important reasons of FIRS. The "Uncontrolled" systemic inflammatory response due to infection or hypoxia is the main mechanism of FIRS. FIRS is closely related to adverse neonatal outcome such as premature delivery, bronchopulmonary dysplasia, neonatal early-onset sepsis, neonatal brain injury, and neonatal necrotizing enterocolitis. The clinical performance of FIRS is often atypical and easily overlooked, but may result in serious outcomes in the neonatal period, such as cerebral palsy, multiple organ failure, and even death. This article summarizes the research progress in the clinical diagnosis, pathogenesis and adverse neonatal outcome of FIRS in recent years.

Key words: Fetal inflammatory response syndrome, Systemic inflammatory response syndrome, Fetal diseases, Premature birth, Bronchopulmonary dysplasia, Neonatal early-onset sepsis, Neonatal brain injury, Neonatal necrotizing enterocolitis, Adverse neonatal outcome