Is it possible to monitor fetal movements with a wearable device? A review of novel technologies

Stillbirth is often preceded by reduced fetal movements and obstetric intervention is necessitated for stillbirth prevention. Yet, despite fetal movements being one of the few tangible ways a pregnant woman and the clinical team can assess the wellbeing of her baby, there are few validated, objective means for pregnant women to quantify the frequency and nature of an unborn baby's movements. Traditional methods of assessing fetal wellbeing such as cardiotocography and fetal movement charts have a lack of diagnostic accuracy, and often lead to false positive intervention. The need for fetal movement counting has led to the development of objective methods to attempt to quantify movements. Some are based on electrocardiography, others on the principles of accelerometery, phonography and optical fibre technology. This review paper not only explores these technologies and evaluates the state-of the-art fetal movement monitoring, but this review uniquely explains the engineering principles underpinning the various technologies, and explores the importance and practice of fetal movement monitoring. To this end, we conclude that there is still a need for the continued development of innovations which will enable a pregnant woman to carry out everyday activities, whilst confident in the knowledge that her unborn child's wellbeing is being accurately monitored, and that feedback from the monitoring device is readily accessible to her.