When Does Perimenopause Start?
Perimenopause typically begins in a woman's mid-40s, though symptoms and hormonal changes can start as early as the mid-30s in some women, and the transition lasts approximately 5 years until menopause is confirmed at a median age of 51 years. 1, 2
Age of Onset
The median age of menopause in the United States is 51 years (range 41-59 years), but ovarian estrogen and progestin production begins declining years before complete cessation of menses 1
The average duration of perimenopause is approximately 5 years, characterized by wide hormone fluctuations and irregular menstrual cycles preceding menopause 3, 2
Hormonal changes can begin in regularly menstruating women in their mid-30s, with the earliest detectable change being a fall in ovarian inhibin B secretion, followed by rising follicle-stimulating hormone levels 2, 4
Symptoms may occur as early as age 35, with significant differences in symptom frequency and severity appearing between age groups in women aged 30-50 5
Clinical Recognition
Diagnosis should be based on menstrual history and age without relying on laboratory test results, as single hormone measurements provide little useful information during this highly variable transition 6, 2
Self-assessment of going through the transition has moderate accuracy (positive likelihood ratio 1.53-2.13), while hot flashes (LR+ 2.15-4.06) and night sweats (LR+ 1.90) are the most predictive symptoms 6
No single symptom or test is accurate enough by itself to definitively rule in or rule out perimenopause 6
Important Clinical Considerations
Contraception should continue until menopause is confirmed (12 months of amenorrhea) or age 50-55 years, as the median age of definitive loss of natural fertility is 41 years but can extend to age 51 7, 8, 3
Approximately 5% of women experience early menopause before age 45, and about 3.6% of women experience premature menopause before age 40 1, 7
Blood pressure and lipid monitoring during the menopausal transition is warranted, as LDL levels generally rise and HDL levels decline during estradiol decline 1
Common Pitfall to Avoid
Do not order FSH or inhibin B levels to predict menopause proximity or confirm perimenopausal status – these tests are documented to be ineffective due to the erratic hormone fluctuations characteristic of this transition 2, 4. Clinical history remains the gold standard for assessment.