Numerical simulation of labour and associated foetal brain loading

During vaginal labour the foetal head moulds to accommodate the geometric constraints of the birth canal and inevitably causes a change in the shape of the brain. Excessive stress during moulding can produce cranial birth injuries with possible long-term sequelae, while malpositioning and prolonged labour can cause pelvic floor damage leading to prolapse later in life. The magnitude of stress (loading) experienced by the foetal skull and brain during the second stage of labour (transit through the vaginal canal) is unknown. Predicting the stresses experienced by the foetal brain and maternal tissues during the second stage of labour and understanding the parameters for successful delivery would help create diagnostic tools for predicting the risk of injury during vaginal labour and therefore prevention. Predicting the risk of injury during vaginal labour could also open up the possibility of distinguishing between injuries sustained during pregnancy, labour, and post-partum.

Previous attempts at estimating the stress and strain experienced by the maternal tissues during labour, have predominantly been with rigid unmoulding foetal heads. A key mechanism for a 'successful' labour is the ability of the foetal skull to mould and so the interaction between moulding skull and maternal tissues is key for predicting both the maternal and foetal loading. Two studies have simulated the first stage of labour (contractions of the uterus before descent into the vaginal canal) with a mouldable foetal skull but these studies have not investigated the loading experience by the foetal brain during labour. Therefore successfully predicting the foetal brain loading during labour alongside the loading on the maternal tissues during the second stage of labour would be significant progress in the field. Additionally, parameterising the model would be the beginning of building a patient specific diagnostic tool for planning when medical intervention is needed.

This study aims to predict the loading of the foetal head and the maternal tissues associated with labour and understand the parameters that most greatly influence the risk of injury, through in silico simulation. This study proposes to build a finite element (FE) model of the maternal anatomy using the geometry of a late stage pregnancy through collaboration with Columbia University, NY (Professor Kristin Myers). The foetal anatomy will be represented by a foetal head FE model, of a 7-day-old infant, supplied by Cardiff university (Prof Mike D. Jones). Existing material response data of the associated tissues will be used to characterise the model. The second stage of labour will be simulated by imposing a trajectory on the foetal head. The model will then be parameterised and existing knowledge on the risk factors associated with vaginal labour will be used to determine which parameters of the model to vary.

This project falls within the EPSRC 'Healthcare technologies' research area and specifically the grand challenge of 'Optimising Treatment'.