- Females are considered to be of non-childbearing potential if they have documented tubal ligation or hysterectomy; or are postmenopausal, defined as 12 months of spontaneous amenorrhea [in questionable cases a blood sample with simultaneous follicle stimulating hormone (FSH) > 40 MlU/ml and estradiol < 40 pg/ml (<147 pmol/L) is confirmatory]