Sonar BPD and fetal age. Definition of the relationship.
D002508:Cephalometry; D005314:Embryonic and Fetal Development; D005260:Female; D005865:Gestational Age; D006801:Humans; D008433:Mathematics; D008722:Methods; D010294:Parietal Bone / Q000033:anatomy & histology*; D011247:Pregnancy; D011336:Probability; D013223:Statistics as Topic; D013997:Time Factors; D014465:Ultrasonics