title: Study on the influence of the fetus head molding on the biomechanical behavior of the pelvic floor muscles, during vaginal delivery.
abstract: Pelvic floor injuries during vaginal delivery are considered a significant risk factor to develop pelvic floor dysfunction. The molding of the fetus head during vaginal delivery facilitates the labor progress, since it adjusts to the birth canal geometry. In this work, a finite element model was used to represent the effects induced by the passage of the fetus head on the pelvic floor. The numerical model used for this simulation included the pelvic floor muscles attached to the bones, and a fetus body. The model of the fetus head included the skin and soft tissues, the skull with sutures and fontanelles, and the brain. The fetus head movements during birth in vertex position were simulated: descent, internal rotation and extension. Two models of the fetus head were compared: a rigid and a deformable one, with the inclusion of the cranial sutures. The influence of the fetus head molding on the pelvic floor muscles was analyzed by evaluating their reaction forces, stretch, and stress and strain fields. Additionally, anatomical indices for the molding of the fetal skull were obtained and compared with clinical data. The passage of the deformable fetus head through the birth canal leads to a reduction of 17.3% on the reaction forces on the pelvic floor muscles when compared to the ones of a rigid head. Furthermore, the fetus head molding implies inferior resistance to rotation resulting in a reduction of 1.86% in muscle stretching. Quantitative evaluation of the fetus head molding showed good agreement with clinical experiments.
authors.affiliation: INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: M E T
authors.initials: ME
authors.lastname: Silva
authors.affiliation: INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: D A
authors.initials: DA
authors.lastname: Oliveira
authors.affiliation: INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: T H
authors.initials: TH
authors.lastname: Roza
authors.affiliation: Department of Gynecology and Obstetrics, Centro Hospitalar de São João-EPE, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal.
authors.forename: S
authors.initials: S
authors.lastname: Brandão
authors.affiliation: INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal. Electronic address: mparente@fe.up.pt.
authors.forename: M P L
authors.initials: MP
authors.lastname: Parente
authors.affiliation: Department of Gynecology and Obstetrics, Centro Hospitalar de São João-EPE, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal; INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: T
authors.initials: T
authors.lastname: Mascarenhas
authors.affiliation: INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: R M
authors.initials: RM
authors.lastname: Natal Jorge
mesh_terms: D001696:Biomechanical Phenomena; D003198:Computer Simulation; D005260:Female; D005333:Fetus / Q000033:anatomy & histology*; D020342:Finite Element Analysis; D006257:Head / Q000033:anatomy & histology; D006801:Humans; D021621:Imaging, Three-Dimensional; D008954:Models, Biological; D009126:Muscle Relaxation; D018482:Muscle, Skeletal / Q000502:physiology*; D036801:Parturition; D017773:Pelvic Floor / Q000502:physiology*; D011247:Pregnancy
keywords: Constitutive model; Fetus head molding; Finite element method; Material parameters; Pelvic floor disorders