Increased apoptosis in human amnion is associated with labor at term

PROBLEM: To characterize whether increased apoptosis in human amnion was associated with labor at term. METHOD OF STUDY: Human amnion were obtained from term patients with vaginal delivery (n = 5) or who underwent elective Cesarean section (C/S) without labor (n = 5). Apoptosis was performed by the TUNEL (Terminal dUTP Nuclear End Labeling) assay. All nucleated cells stained with propidium iodide in the amnion epithelial cells were identified in red fluorescence. TUNEL positive apoptotic nuclei were identified in green fluorescence. Five random fields of each specimen were blindly counted by investigators. The percentage of apoptotic nuclei of total nuclei (apoptotic index) was calculated and compared between the two groups (25 microscopic fields for each group, respectively). RESULTS: Patients with term labor had a significantly higher mean apoptotic index in amnion epithelial cells than that with elective C/S without labor (27.3 +/- 4.1% versus 3.6 +/- 1.6%, P < 0.001). CONCLUSIONS: Our data indicate that apoptosis in human amnion is significantly increased and associated with labor at term.