Description

• Natural menopause: 12 consecutive months of amenorrhea in a nonpregnant woman ≥40 years of age; mean age of 51 years; resulting from loss of ovarian activity
• Perimenopause/menopausal transition (MT): the period from the onset of irregular menses to the final menstrual cycle. Begins on average 4 years before menopause; starts at mean age of 47 years
• Postmenopause: usually >1/3 of a woman’s life
• Primary ovarian insufficiency: irregularity or cessation of ovulatory cycles before age 40 years
• Surgical menopause: removal of functioning ovaries leading to immediate menopause

Epidemiology

• The median age of menopause is 51 years.
• 5% of women undergo menopause after age 55 years; another 5% between ages 40 and 45 years
• Occurs earlier in Hispanic women and later in Japanese American women as compared with Caucasians

Incidence
In the United States, 1.3 million women reach menopause annually.

Etiology and Pathophysiology

• As women age, the number of ovarian follicles decreases: Ovarian production of estrogen varies and then decreases. Follicle-stimulating hormone (FSH) production varies and then increases.
• Insufficient estradiol production leads to the absence of the luteinizing hormone (LH) surge, resulting in anovulation. Anovulation causes lack of progesterone production.
• Failure to produce estradiol leads to thinning of endometrial lining and eventually menstruation ceases.
• Estrone (produced by adipose tissue) becomes the dominant form of estrogen during menopause.

Risk Factors

• Aging
• Oophorectomy/hysterectomy
• Sex chromosome abnormalities (e.g., Turner syndrome and fragile X syndrome)
• Family history of early menopause
• Smoking (earlier age of onset by 2 years)
• Chemotherapy and/or pelvic radiation
• Low body mass index

General Prevention

Menopause is a physiologic event and cannot be prevented. It is associated with increased risk of long-term medical issues, including cardiovascular disease (CVD) and osteoporotic fractures.

• Decrease risk of CVD by:
  • Increasing exercise
  • Maintaining healthy diet and a healthy weight
  • Avoiding tobacco use
  • Treating hypertension, hyperlipidemia, and diabetes mellitus
• Decrease risk of osteoporotic fractures with:
  • Weight-bearing exercise and fall prevention
  • Avoidance of smoking and excessive alcohol intake
  • Dietary calcium of 1,200 mg/day
  • Adequate vitamin D intake (800 to 1,200 IU daily)