title: An ultrasonic pulsed Doppler instrument for monitoring human fetal breathing in utero.
mesh_terms: D004301:Doppler Effect; D005260:Female; D005323:Fetal Monitoring / Q000295:instrumentation*; D005333:Fetus / Q000502:physiology; D006801:Humans; D011247:Pregnancy; D012119:Respiration; D014463:Ultrasonography