The present invention relates to the use of antagonists of oxytocin, antagonists of oxytocin and vasopressin, or antagonists of vasopressin, or their pharmaceutically accepted salts, or their combinations with other drugs for the manufacture of a medicament which main profile of action is inhibition of oxytocin and/or vasopressin receptors in non-pregnant uterus of mammals, that results in improvement of uterine receptivity in embryo transfer. It further relates to the application of these substances for the manufacture of a medicament for regulating the uterine contractile activity in cases of artificial insemination.