Modeling the second stage of labor.

Vaginal delivery is the primary cause of levator ani muscle injury, which is in turn the leading factor contributing to pelvic floor disorders including pelvic organ prolapse and urinary stress incontinence. Existing biomechanical models of childbirth have provided some understanding of pelvic floor function during delivery and have helped in the investigation of preventative strategies. The modeling frameworks for childbirth simulation are described with emphasis on (1) the recent advances in medical imaging quality and computational power; (2) improvements in the anatomical representation of the pelvic floor and fetal head; (3) more realistic boundary conditions for delivery; and (4) mechanical properties determined from experiments. Researchers have used these models to analyze childbirth mechanics and identify anatomical and mechanical features of the maternal pelvic floor, shape of the fetal head, and delivery techniques that potentially contribute to a difficult labor and higher risk of levator ani muscle injuries. The challenges to be addressed for these frameworks to be clinically useful are also discussed, including: (1) the improvements required to more accurately simulate the second stage of labor; (2) automatic segmentation of medical images and creation of customized computer models; (3) acquisition of individual specific pelvic floor mechanical properties; and (4) construction of statistical models for rapidly predicting the indices of childbirth mechanics. Within the next decade, it is likely that biomechanical models of childbirth will be sufficiently well informed and functional for personalized birth planning, and as educational tools for clinicians. WIREs Syst Biol Med 2016, 8:506-516. doi: 10.1002/wsbm.1351 For further resources related to this article, please visit the WIREs website.