The Measurement and Imaging Core will assist with measurements of perineal geometry during the late second stage of labor in 50 women, and of pelvic floor load-displacement behavior in 32 women using a posterior weighted speculum at the time of pelvic surgery. The Core will assist with clinical measurements and standardized data sets from magnetic resonance (MR) imaging to be made on the 175 and 150 women completing Projects 2 and 3, respectively. In Projects 2 &3, subject-specific pelvic floor model geometries will be developed from reconstructing the magnetic resonance (MR) images. Additionally, in Project 2 the post natal recovery of normal MR signal intensity will be tracked over time in the pubovisceral muscles. In Project 3, MR measurements of posterior vaginal wall geometry will be made. Lastly, the Core will provide bioengineering and technical support to each project. For Projects 2 &3 it will provide technical support for all urethral pressure measurements (MUCPR and MUCPMvc) to be made using 8F catheter, maintain the hardware and software of the instrumented speculum used to measure levator ani contractile properties (LAR and I_AMVC,), and analyze and provide cleaned data sets to Core A for statistical analysis.