RT Book, Section A1 Schwinghammer, Terry L. A1 DiPiro, Joseph T. A1 Ellingrod, Vicki L. A1 DiPiro, Cecily V. SR Print(0) ID 1178896899 T1 Hormone Therapy in Women T2 Pharmacotherapy Handbook, 11e YR 2021 FD 2021 PB McGraw Hill PP New York, NY SN 9781260116694 LK accesspharmacy.mhmedical.com/content.aspx?aid=1178896899 RD 2024/03/29 AB Perimenopause begins with the onset of menstrual irregularity and ends 12 months after the last menstrual period, which marks the beginning of menopause. Menopause is the permanent cessation of menses caused by the loss of ovarian follicular activity. Women spend about 40% of their lives in postmenopause.