Objectives: To gain insight into the process of labor and the effects of labor on placental gene expression, we performed a microarray analysis to identify the differentially expressed transcripts that may participate in labor onset and progression.
Methods: We compared expression profiles in placentas from 16 women who underwent elective non-labored cesarean section and from seven women who underwent vaginal delivery. Oligonucleotide probes representing 55,000 genes were used to measure gene expression. Differential gene expression was evaluated using the Student's t-test and fold change assessment and reverse transcription PCR was used to validate the differentially expressed genes.
Results: A total of 351 genes were found to be differentially expressed between the two groups. Among these differentially expressed genes, 344 genes were up-regulated and seven were down-regulated. These differentially expressed genes involved 15 categories including genes involved in stress response, immune response, cell death, coagulation, and blood vessel development which are considered to be most closely associated with the inflammatory response that characterizes labor.
Conclusion: A total of 351 differentially expressed genes of 15 categories were found in the placentas of the vaginal delivery group, indicating a diversity of gene expression alteration and complexity in the labor process. These gene expression changes could be a cause of labor onset and progress or simply an effect of labor.