Direct sensing of heart rate and uterine pressures is done immediately before delivery,
when direct access to the fetal scalp is achieved. Fetal-scalp electrodes sense the electrical
activity of the heart, and intrauterine pressure transducers measure uterine pressure.
To aid in the determination of the physiological status of the fetus and the mother, monitoring
of the fetal and maternal arterial blood oxygen saturation is performed (see Figure
93-3).