Perimenopause

By RRM Academy Reviewed by Dr. Naomi Whittaker, MD, Board-Certified OBGYN, MIGS, NFPMC, FCI Updated July 26, 2026

Perimenopause is the biological transition period preceding menopause, typically lasting several years with considerable variation between women, during which ovarian function declines progressively and menstrual cycle patterns become irregular. The staging criteria established by the Stages of Reproductive Aging Workshop (STRAW+10) define early perimenopause by variable cycle length and late perimenopause by cycles 60 or more days apart, extending through the first 12 months after the final menstrual period.¹ This transition follows biology, not a specific calendar age, though it most commonly begins in the mid-forties.

Hormonally, perimenopause brings volatility rather than simple decline. FSH rises irregularly, AMH falls progressively as the ovarian follicle pool depletes, estradiol fluctuates widely between cycles, and anovulatory cycles become more frequent.¹ This hormonal instability produces the vasomotor symptoms, sleep disruption, and mood changes commonly associated with the menopausal transition.

Fertility does not end at the onset of perimenopause. Ovulation still occurs, and conception remains possible, though the probability of successful pregnancy declines as anovulatory cycles increase and egg quality diminishes with advancing follicle depletion. Couples who do not wish to conceive should understand that contraceptive needs persist beyond a single missed cycle: guideline practice sets the threshold at 12 consecutive months of amenorrhea in women aged fifty and older, but 24 consecutive months in women younger than fifty, because ovarian activity can still resume during that longer window before true Menopause is confirmed. For couples pursuing pregnancy during perimenopause, the clinical evaluation differs from care in younger women, with particular attention to ovarian reserve, cycle quality, and the frequency of ovulatory cycles.

This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.