Effects in vitro of progesterone and two 5 alpha-reduced progestins, 5 alpha-pregnane-3,20-dione and 5 alpha-pregnane-3 alpha-ol-20-one, on contracting human myometrium at term - Lofgren,M.; Holst,J.; Backstrom,T. (Acta Obstet Gynecol Scand, 1992)