Increased Apoptosis in Chorionic Trophoblasts of Human Fetal Membranes with Labor at Term

To determine the association of apoptosis in the layers of human fetal membranes with labor at term.

Human fetal membranes were collected from elective cesarean sections (n = 8) and spontaneous vaginal deliveries (n = 8) at term. The extent of apoptosis within the layers of fetal membranes was determined using terminal deoxynucleotidyl transferase deoxy-UTP-nick end labeling (TUNEL) immunohistochemical assay and western blots. For TUNEL assays, 5-μm sections of formalin fixed membranes were used and the apoptotic index (number of apoptotic nuclei per total nuclei ×100) was determined in 5 independent microscopic fields. For Western blotting, proteins isolated from the amnion and choriodecidua layers were blotted against pro-apoptotic active caspase-3 and anti-apoptotic and Bcl-2. Data were expressed as the means ± SD and Student's t-test was used for statistical analysis.

There was no statistical difference in maternal age, gestational age, gravidity, parity, race, and smoking between patients who delivered at term via either elective cesarean or vaginally. Apoptotic index in chorionic trophoblasts of membranes obtained after vaginal delivery was higher than those obtained from elective cesarean (11.57 ± 4.98 % and 4.05 ± 2.4 % respectively, p = 0.012). The choriodecidua layers after vaginal deliveries had higher expression of the pro-apoptotic active caspase-3 and less expression of the anti-apoptotic BcL-2 than those obtained from elective cesarean sections.

Labor at term is associated with increased apoptosis in chorionic trophoblast cells of human fetal membranes. The cause-effect relation between apoptosis in fetal membranes and labor warrants further investigations.