title: A continuous wave Doppler ultrasound method of recording fetal breathing in utero.
mesh_terms: D005260:Female; D005318:Fetal Heart / Q000502:physiology; D005323:Fetal Monitoring; D005333:Fetus / Q000502:physiology*; D006339:Heart Rate; D006801:Humans; D011247:Pregnancy; D012119:Respiration; D013057:Spectrum Analysis; D014465:Ultrasonics / Q000295:instrumentation; D014463:Ultrasonography