Micro-haemodynamics at the maternal–fetal interface: Experimental, theoretical and clinical perspectives

The placenta is a vital interface between the mother and her developing fetus. Micro-haemodynamics of the placenta, where the particulate nature of blood flow cannot be ignored, mediates the relationship between the organ's structure and its function. However, the placenta's complex architecture and its relation to pregnancy pathologies remain poorly understood. This review covers current challenges in characterising placental micro-haemodynamics. Recent progress in three-dimensional multiscale imaging has stimulated the development of image-based theoretical models, but existing approaches do not fully harness the available data, and new tools are needed for the assimilation of complex imaging datasets. Although the placenta at term is available for in vivo imaging or ex vivo experimentation, insight into placental micro-rheology is limited, necessitating the use of biomimetic models. Microfluidic approaches offer opportunities for well-controlled characterisation of micro-rheology in complex geometries, but challenges remain in the robust fabrication of these systems. Recent advances in high-performance simulations for suspension flows enable parametrisation of key physical processes at the micro-scale. Future progress can be made by optimising computational architecture and integrating micro-haemodynamics with solute transport. Both experimental and computational approaches require translation to the organ scale. New upscaling approaches will need to accommodate non-local interactions in microvascular network flows and address the lack of clear scale separation across the placental architecture. Together, recent advances in cross-disciplinary imaging and modelling over the last ten years have opened a pathway for an in silico human placenta, accelerating the development of precision obstetrics medicine in the next decade.