Elastic properties and yield stress of fetal membranes

This is a presentation of a biomechanics project from almost 30 years ago, that, despite the long delay, is both relevant today and may be interesting from a historical perspective. Premature rupture of the amniotic sac membranes enclosing the fetus is, as yet, a not fully understood process, but may related to the mechanical properties of those membranes. The late biomechanics pioneer Tom McMahon and I developed a method for testing the yield stress of fetal membranes and found it to be homogeneous throughout individual samples. The method was: 1. insensitive to initial stretch, 2. avoided damaging contact with the membrane during stress-testing, and 3. modeled the mechanical properties using a power-law relationship. Because the clinical samples were from normal deliveries, clinical correlation remains as an unfinished aim of this project.