Sonar as a method of studying prenatal development.
D002508:Cephalometry; D000013:Congenital Abnormalities / Q000175:diagnosis; D005314:Embryonic and Fetal Development; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D014465:Ultrasonics