Changes in the levels of progesterone, corticosteroids, estrone, estradiol-17 beta, luteinizing hormone, and prolactin in the peripheral plasma of the ewe during late pregnancy and at parturition. - Chamley WA; Buckmaster JM; Cerini ME; Cumming IA; Goding JR; Obst JM; Williams A; Winfield C (Biology of reproduction, 1973)