title: Maternal-fetal urea concentration difference in man: metabolic significance.
mesh_terms: D005260:Female; D005333:Fetus / Q000378:metabolism*; D006801:Humans; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D013997:Time Factors; D014469:Umbilical Arteries; D014508:Urea / Q000097:blood* / Q000378:metabolism; D014680:Veins
chemical_list: D014508:Urea