Mechanical Environment Pregnancy With Short Cervix

The objective of this study is to quantify the mechanical environment of pregnancies complicated by a short cervix and randomized in the Trial of Pessary in Singleton Pregnancies with a Short Cervix study with ultrasound imaging and aspiration. Aim 1: To determine the biomechanical properties of a prematurely remodeled cervix. Aim 2: To determine the impact of pessary placement on the biomechanical properties of a prematurely remodeled cervix and establish if the pessary reduces the mechanical load on the cervix through computer modeling informed by ultrasonographic measurement and cervical stiffness measurements. Aim 3: To determine if the differences in the cervical biomechanical properties after pessary placement lead to improved birth outcomes as compared to the progesterone only group.