PFM.37 Cyclic tensile strain increases PGE2 release leading to weakening of the human term amniotic membrane

Introduction Uterine contractions, blood and infection may weaken the amniotic membrane (AM) leading to loss in biomechanical properties mediated by PGE 2 release. We investigated AM mechanical properties and the effect of cyclic tensile strain (CTS) on PGE 2 release and tissue composition in term AM. Methods AM from the cervix ( C AM) and placental regions ( P AM) from elective term Caesarean section births were stained with India ink to identify fibre orientation either parallel ( II ) or perpendicular ( ⟂ C ) to the direction of applied strain and specimens strained to failure to calculate Tangent Modulus (TM). In separate experiments, dumb-bell shaped specimens underwent CTS (2%) and were analysed for collagen, elastin, GAG and PGE 2 release. Results Mechanical properties were dependent on fibre orientation with greater TM values for C AM/ P AM II compared to C AM/ P AM ⟂ (all p P AM II (7.5MPa) vs C AM II (4.9 MPa; p In C AM II and P AM II , CTS significantly increased PGE 2 values when compared to unstrained control samples (all p Conclusion CTS of the AM mimicking labour increased PGE2 release that reduced tissue composition leading to membrane softening. AM biomechanical properties are influenced by fibre orientation with relation to the direction of strain.