- Objective The aim of this study was to identify differential expression of microRNAs (miRNAs) in chorioamniotic membranes with advancing gestation, labor, and inflammation. Study Design Expression profiles of 157 miRNAs in the chorioamniotic membranes were obtained from patients in the following groups: 1) term not in labor (n = 10); 2) term in labor (n = 10); 3) preterm labor with histologic chorioamionitis (n = 9); and 4) without histologic chorioamnionitis (n = 10). Results More than 95% of the miRNAs screened were expressed. Gestational age-dependent changes in expression were observed for 13 miRNAs. No differences in miRNA expression were observed between women without labor and women in labor. Membranes with chorioamnionitis displayed increased expression of miR-223 and miR-338. Gene Ontology analysis of genes targeted by differentially expressed miRNAs revealed enrichment for specific biological process categories. Conclusion Chorioamniotic membranes with advancing gestational age and chorioamnionitis are associated with the differential expression of a subset of miRNAs.