The extent to which external transdermal light sources illuminate the uterine environment is unknown. Recent experimental work indicates that the human fetus responds to external visual stimuli such as laser diodes, and initial modelling work suggests the fetus may not develop in a completely dark environment as previously assumed. Development of the human visual system begins within the womb, and there is motivation in fields such as developmental psychology, transabdominal oximetry, and photoacoustics to explore the extent to which light penetrates maternal abdominal tissue. In this study, we develop and adapt a Monte Carlo model that uses third trimester histological properties of maternal tissue in simulating transdermal monochromatic point light sources. We use the results of this modelling to determine approximate levels of third trimester uterine illumination from such stimuli, discuss the scope for multiple stimuli to be visibly distinct in utero, and suggest improvements for future experimental work.

The extent to which external light sources illuminate the uterine environment is not completely known. Recent experimental work has indicated that the human fetus will respond to external visual stimuli, and initial modelling work has suggested that the fetus may not develop in a completely dark environment as previously thought. The development of the human visual system begins within the womb, and there is experimental motivation to explore the extent to which light penetrates maternal abdominal tissue. In this study, we develop and adapt a Monte Carlo model that simulates third trimester histological properties of maternal tissue in order to understand the extent to which the womb is illuminated by external point light sources. We next use the results of this mathematical modelling to determine approximate levels of third trimester uterine illumination and suggest improvements for future experimental work.