A monitor for the continuous recording of fetal head-to-cervix force

The importance of soft tissue resistance to the progress of labour has been known for some time. The means to quantify and compare this property between different labours has however not been available. We have developed a system to produce a real-time recording of fetal head-to-cervix force (HCF) and intrauterine pressure (IUP). A study involving 31 patients demonstrated a good correlation between 50th percentile of active force (AF) and mode of delivery. A further study of 18 patients of differing parities confirmed this relationship, and analysis of the data by parity and cervical dilatation rate also suggested that a ratio of) mean active force to mean active pressure gives a quantitative indication of cervical compliance. HCF and IUP are displayed in real-time and calculations are performed "off-line". A new system is being developed which will display mean AF, mean active pressure (AP), mean AF / mean AP ratio and the linear relationship between AF and AP. This information obtained should allow evaluation and improvement of treatments for slow labour.