The history of ultrasonography in obstetrics.
D005060:Europe; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis; D005324:Fetal Movement; D049673:History, 20th Century; D006801:Humans; D011247:Pregnancy; D011296:Prenatal Diagnosis; D014463:Ultrasonography / Q000266:history*; D014481:United States