RT Book, Section A1 Wells, Barbara G. A1 DiPiro, Joseph T. A1 Schwinghammer, Terry L. A1 DiPiro, Cecily V. SR Print(0) ID 1144734719 T1 Menopausal, Perimenopausal, and Postmenopausal Hormone Therapy T2 Pharmacotherapy Quick Guide YR 2017 FD 2017 PB McGraw-Hill Education PP New York, NY SN 9781259586439 LK accesspharmacy.mhmedical.com/content.aspx?aid=1144734719 RD 2024/04/19 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.