Premature rupture of membranes (PROM), with a prevalence of 15.3% in China, frequently results in adverse pregnancy outcomes. In this study, we aimed to identify amino acid metabolites that were differentially expressed in PROM versus healthy controls (HC) using targeted metabolomics and further explored their mechanisms of action with in vitro models.Inclusion and exclusion criteria were established to recruit 50 PROM and 50 HC cases for targeted metabolomics analysis. Twenty-three amino acid metabolites were quantified in the secretions of the posterior vaginal fornix of pregnant women between 31 and 36 weeks of gestation. Glutamine (0.0216 vs. 0.037 μg/mg, P = 0.003, AUC = 72.1%) was identified as the most differentially expressed amino acid metabolite between PROM and HC groups, and had a negative correlation with the abundance of Gardnerella (r=-0.3868, P = 0.0055), Megasphaera (r=-0.3130, P = 0.0269), and Prevotella (r=-0.2944, P = 0.0380), respectively.In amniotic epithelial cell and macrophage co-culture model, Glutamine reduced inflammatory cytokines and chemokines expression and suppressed macrophage chemotaxis. In LPS stimulated RAW 264.7 inflammation model, Glutamine inhibited the expression of inflammatory proteins iNOS and COX-2, down-regulated mRNA transcription of TNF, IL-6, and IL-1β, and reduced the production of reactive oxygen species through inhibiting NF-κB signaling pathway, and therefore demonstrated its anti-inflammatory effect. Furthermore, Glutamine protected amniotic epithelial cell from autophagy and stimulated its proliferation, therefore may intensify fetal membrane and prevent PROM in vivo.Our results suggested that low Glutamine level in vaginal secretion can be used as an indicator for PROM, and local Glutamine supplementation is a potential intervention and prevention strategy for PROM.