Abstract: Preterm labor refers to the delivery between 28 weeks and less than 37 weeks of gestation. The immature development of multiple organ systems of premature infants and related complications are important causes of neonatal morbidities and mortalities. The difficulty of the prevention and treatment of preterm labor is mainly due to its multiple causes. Currently, the pathogenesis is still not clear. A few studies have shown that infection is the main factor, which will produce inflammatory mediators that induce uterine contraction through many ways, thus promoting preterm labor. In the past, fetal fibronectin(FFN), transvaginal cervical tube length and serum inflammatory mediators were widely used to predict the occurrence of late symptomatic preterm labor, while the application of mid-term prediction of preterm labor was limited. It has been confirmed that the related inflammatory mediators such as interleukin-6(IL-6), IL-16, C-reactive protein (CRP), adiponectin, antimicrobial peptide, etc. produced by gestational tissue in chorioamnionitis directly enter amniotic fluid and meanwhile amniocentesis is commonly used in the field of prenatal diagnosis. Therefore, further study on the inflammatory mediators in amniotic fluid in the second trimester of pregnancy is expected to provide a new method for the prediction of preterm labor in the second trimester.

Key words: Chorioamnionitis, Premature birth, Amniotic fluid, Inflammatory mediators