title: Plasma progestagens and oestrogens in fetus and mother in late pregnancy.
abstract: Normal Thoroughbred and catheterized Pony mares and their fetuses were used. Fetal oestrogen and progestagen concentrations in late gestation were much higher than maternal values. A major feature of the umbilical steroid concentrations was a large venous-arterial difference in progestagens and total oestrogens throughout late gestation which may indicate a metabolic cycle in the fetus between progesterone and other steroid metabolites. Metabolites of 20alpha-dihydroprogesterone were present in high concentrations in maternal and fetal plasma. In Thoroughbreds, and to a lesser extent in Pony mares, plasma progestagens rose towards parturition while total plasma oestrogen fell. The only oestrogen which showed a rise in concentration near term was oestradiol-17beta. In one Pony mare and fetus, fetal plasma progestagen fell 24 to 36 hr before parturition when maternal peripheral progestagen concentrations remained high.
mesh_terms: D000818:Animals; D004967:Estrogens / Q000097:blood*; D005260:Female; D005312:Fetal Blood / Q000032:analysis; D005313:Fetal Death / Q000097:blood; D005865:Gestational Age; D006736:Horses / Q000097:blood*; D011247:Pregnancy; D011270:Pregnancy, Animal; D011374:Progesterone / Q000097:blood; D011372:Progestins / Q000097:blood*; D014469:Umbilical Arteries; D014471:Umbilical Veins
chemical_list: D004967:Estrogens; D011372:Progestins; D011374:Progesterone