Uterine activity is sensed by passing light through the patient's abdominal wall and detecting the light reflected from abdominal tissues. The intensity of the reflected light varies with the state of contraction of the patient's uterus. The use of light for monitoring uterine activity ...http://www.google.es/patents/US6169913?utm_source=gb-gplus-sharePatente US6169913 - Non-invasive uterine activity sensor
