title: Doppler ultrasonocardiography of twins.
mesh_terms: D004562:Electrocardiography / Q000295:instrumentation; D005260:Female; D005318:Fetal Heart; D006801:Humans; D011247:Pregnancy; D011272:Pregnancy, Multiple; D011296:Prenatal Diagnosis; D014427:Twins; D014463:Ultrasonography