title: Evaluation of first-trimester pregnancy by ultrasound.
mesh_terms: D000650:Amnion / Q000033:anatomy & histology; D002823:Chorion / Q000033:anatomy & histology; D004622:Embryo, Mammalian / Q000033:anatomy & histology / Q000502:physiology; D005069:Evaluation Studies as Topic; D005260:Female; D005318:Fetal Heart / Q000502:physiology; D005333:Fetus / Q000033:anatomy & histology; D005865:Gestational Age; D006339:Heart Rate; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D014465:Ultrasonics