title: A second means of identifying fetal breathing movements using Doppler ultrasound.
abstract: A new low-frequency Doppler shift signal associated with fetal breathing has been observed. This signal is out of phase with the previously described signal from the inferior vena cava and originates from the umbilical vein.
mesh_terms: D004301:Doppler Effect; D005260:Female; D005323:Fetal Monitoring; D005333:Fetus / Q000502:physiology*; D006801:Humans; D011247:Pregnancy; D012119:Respiration; D014463:Ultrasonography