Abstract: A device and method for monitoring cervical dilation, and descent of the presenting part, during labor. An extracorporeally located ultrasound transmitter transmits ultrasound signals into the body of the patient. Small ultrasound reflectors located on either side of the cervical os, and on the fetal presenting part, reflect the ultrasound signals back to extracorporeal ultrasound receivers. Spectral and acoustic characteristics of the received ultrasound signals are analyzed to identify the relative locations of the reflectors, and the trigonometric relationships between the reflectors and transmitters are used to calculate the degree of cervical dilation, and the descent of the fetal presenting part. In an alternative embodiment, passive ultrasound receivers are used instead of ultrasound reflectors.