title: The efficiency of Doppler-technique in the first trimester of pregnancy.
mesh_terms: D000029:Abortion, Legal; D005260:Female; D005313:Fetal Death / Q000175:diagnosis; D005318:Fetal Heart; D005865:Gestational Age; D006326:Heart Auscultation; D006801:Humans; D008722:Methods; D011247:Pregnancy; D011555:Pseudopregnancy; D014463:Ultrasonography