Effects of Fetal Position on the Loading of the Fetal Brain During the Onset of the Second Stage of Labor.

During vaginal delivery, the delivery requires the fetal head to mold to accommodate the geometric constraints of the birth canal. Excessive molding can produce brain injuries and long-term sequelae. Understanding the loading of the fetal brain during the second stage of labor (fully dilated cervix, active pushing, and expulsion of fetus) could thus help predict the safety of the newborn during vaginal delivery. To this end, this study proposes a finite element model of the fetal head and maternal canal environment that is capable of predicting the stresses experienced by the fetal brain at the onset of the second phase of labor. Both fetal and maternal models were adapted from existing studies to represent the geometry of full-term pregnancy. Two fetal positions were compared: left-occiput-anterior and left-occiput-posterior. The results demonstrate that left-occiput-anterior position reduces the maternal tissue deformation, at the cost of higher stress in the fetal brain. In both cases, stress is concentrated underneath the sutures, though the location varies depending on the presentation. In summary, this study provides a patient-specific simulation platform for the study of vaginal delivery and its effect on both the fetal brain and maternal anatomy. Finally, it is suggested that such an approach has the potential to be used by obstetricians to support their decision-making processes through the simulation of various delivery scenarios.

A coupled physical-computational methodology for the investigation of short fall related infant head impact injury.

Head injury in childhood is the most common cause of death or permanent disability from injury. However, insufficient understanding exists of the response of a child's head to injurious loading scenarios to establish cause and effect relationships to assist forensic and safetly investigations. Largely as a result of a lack of availability of paediatric clinical and Post-Mortem-Human-Surrogate (PMHS) experimental data, a new approach to infant head injury experimentation has been developed. A coupled-methodology, combining a physical infant head surrogate, producing "real world" global, regional and localised impact response data and a computational Finite-Element (FE-head) model was created and validated against available PMHS and physical model global impact response data. Experimental impact simulations were performed to investigate regional and localised injury vulnerability. Different regions of the head produced accelerations significantly greater than those calculated using the currently available method of measuring the global, whole head response. The majority of material strain was produced within the relatively elastic suture and fontanelle regions, rather than the skull bones. A subsequent parametric analysis was conducted to provide a correlation between fall height and areas of maximum-stress-response and fracture-risk-probability. The FE-head was further applied to investigating fracture risk, simulating injurious PMHS impacts and a good qualitative match was observed. The FE-head shows significant potential for the study of infant head injury and is anticipated to be a motivating tool for the improvement of head injury understanding across a range of potentially injurious head loading scenarios.