Postural position and neurocardiogenic syncope in late pregnancy.

A 23-year-old woman at 34 weeks' gestation developed recurrent syncope due to profound sinus arrest captured on electrocardiography. Syncopal events occurred in the same sitting position. An echocardiogram revealed severe collapse of the inferior vena cava each time the patient changed her posture from a supine to a sitting position, which was related to the syncope.