The invention provides compositions and methods for reducing the volume of menstrual blood loss in a patient, such as a human patient, for instance, that has uterine fibroids, by administration of a gonadotropin-releasing hormone (GnRH) antagonist. Suitable GnRH antagonists useful in conjunction with the compositions and methods described herein include thieno[3,4d]pyrimidine derivatives, such as 3-[2-fluoro-5-(2,3-difluoro-6-methoxybenzyloxy)-4-methoxypheny I]-2,4-dioxo-1,2,3,4-tetrahydrothieno[3,4d]pyrimidine-5-carboxylic acid and the choline salt thereof.