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How can I Tell I am in Perimenopause?

What's going on? Why can't I sleep normally, why am I so grumpy or suddenly anxious, why am I abruptly hot and sweaty? Could I be in perimenopause?

CeMCOR believes that if:

--our experiences have changed (see the Table of characteristic changes)

--our hormone levels have changed (scientific evidence says that perimenopausal estrogen levels are higher1, more variable and unpredictable2; ovulation is less frequent and progesterone levels are lower3)

THEN, it is the start of perimenopause, even if cycles are regular and normal in length. In saying this we differ from the official, current consensus4.

Whatever changes you experience—everything about perimenopause is variable. It is variable within one woman. It is even more variable between different women (even if those women are sisters or relatives). Look forward to change—resilience is needed!

Knowing when normal perimenopause starts

The Centre for Menstrual Cycle and Ovulation Research believes that women begin perimenopause when their menstrual cycles are still regular and of normal lengths Other current  literature says that only women with irregular cycles (cycle lengths varying from one to the next by 7 or more days)4 can be in the “menopause transition” (the official name) for perimenopause.

To help make the changes we experience something on which a diagnosis of “Very Early Perimenopause” can be based5, we created a table of common experience changes (see Table).

Table: Women in midlife with regular menstrual cycles of normal lengths (21-35 days apart) may make a diagnosis of “Very Early Perimenopause” if they experience any 3 of these:


Shorter cycles, mid-sleep wakening and heavier or longer flow occur at some time for most women. Almost 80% of perimenopausal women experience hot flushes/flashes and night sweats6, but not all women start experiencing them when cycles are still regular7. Those that do, often notice night sweats first that cluster around menstrual flow7. Fewer of all perimenopausal women seem to experience increased breast tenderness/lumpiness, more than usual cramps or the start of or severe worsening of migraine headaches.

The start of perimenopause, the “milestone” phases and approximate timeline for the perimenopausal journey are outlined in the Figure8 below. The very early perimenopause phase may last from two to five years; it probably lasts longer in those who start it in their 30s than those beginning changes in their 50s.


The onset of irregular cycles (varying by 6-7 days from the start of one flow to the next) means the beginning of early perimenopause (officially called “Early Menopause Transition”). The onset of Late Perimenopause occurs when one cycle is skipped or it is 60 days from the start of one flow to the start of the next4. A year after the last menstrual flow is needed before we are no longer perimenopausal. This last count-down year is called “Very Late Perimenopause.” 

How long will I have irregular cycles in perimenopause?  

No one really knows the answer. The best guidance we have is from a large study of randomly chosen women ages 45-55 from Massachusetts in the USA. In this study9, it was about three years from irregular menstruation until the final menstruation.

How long from my first skipped cycle until my final period?

Again there are no answers based on studies of women’s experiences. Although previously, gynecological physicians considered “menopause” to literally be the last menstrual flow, menopause doesn’t start until a year after that final menstruation.

How long from my last period until I’m officially menopausal?

Even the standard one year of “Very Late Perimenopause” can become longer if we get another period, as 10-20% of us normally do10. The younger we are, the more likely it is that we will experience a further flow. Then, the “last year clock” starts again!

Is progress regular through the phases of perimenopause?

In looking at the Figure it seems that a perimenopausal woman would make straightforward progress from one phase to the next. The truth is much more complex! A study in women over age 45 from Manitoba in Canada showed that there were 100 different menstrual cycle patterns among 324 menstruating women who were asked about their cycles every 6 months over three years11. Women could go without flow for six months and then have regular flow again for six months11! This extreme variability in perimenopause was later confirmed in a group of American women observed over 3-12 years12

How can I keep track of what’s happening for me?

No matter what the variety of unpredictable experiences perimenopause presents, the best way to understand our own experiences (and to communicate these with health care providers), is to keep the Daily Perimenopause Diary. This tool takes only about two minutes at bedtime each day. By recording your own experiences you can see progress over time. My diary showed me relief from sore and swollen breasts—that were worst when my cycles were regular—as I started skipping cycles; a good study from Australia has proven this pattern13

In summary, there is much about perimenopause that is variable and confusing. The table of early changes and the diagram of phases will help you figure out when you’ve started and what experiences are ahead. For those who have a difficult time, it is a relief to graduate into menopause!   

Reference List

       (1)    Prior JC. Perimenopause: The complex endocrinology of the menopausal transition. Endocr Rev 1998; 19:397-428.

       (2)    Hale GE, Hughes CL, Burger HG, Robertson DM, Fraser IS. Atypical estradiol secretion and ovulation patterns caused by luteal out-of-phase (LOOP) events underlying irregular ovulatory menstrual cycles in the menopausal transition. Menopause 2009; 16(1):50-59.

       (3)    Santoro N, Rosenberg J, Adel T, Skurnick JH. Characterization  of reproductive hormonal dynamics in the perimenopause. J Clin Endocrinol Metab 1996; 81:4,1495-1501.

       (4)    Harlow SD, Gass M, Hall JE, Lobo R, Maki P, Rebar RW et al. Executive summary of the Stages of Reproductive Aging Workshop +10: addressing the unfinished agenda of staging reproductive aging. Climacteric 2012; 15(2):105-114.

       (5)    Prior JC. Clearing confusion about perimenopause. BC Med J 2005; 47(10):534-538.

       (6)    Williams RE, Kalilani L, DiBenedetti DB, Zhou X, Granger AL, Fehnel SE et al. Frequency and severity of vasomotor symptoms among peri- and postmenopausal women in the United States. Climacteric 2008; 11(1):32-43.

       (7)    Hale GE, Hitchcock CL, Williams LA, Vigna YM, Prior JC. Cyclicity of breast tenderness and night-time vasomotor symptoms in mid-life women: information collected using the Daily Perimenopause Diary. Climacteric 2003; 6(2):128-139.

       (8)    Prior JC, Seifert-Klauss VR, Hale G. The Endocrinology of perimenopause - new definitions and understandings of hormonal and bone changes. In: Dvoryk V, editor. Current Topics in Menopause. Bentham Science Publishers Ltd; 2012. 54-83.

       (9)    Brambilla DJ, McKinlay SM, Johannes CB, Burger HG, Green A, Hopper J et al. Defining the perimenopause for application in epidemiologic investigations. American Journal Epidemiology 1994; 140:10:1091-1095.

    (10)    Wallace RB, Sherman BM, Bean JA, Treloar AE, Schlabaugh L. Probability of menopause with increasing duration of amenorrhea in middle-aged women. Am J Obstet Gynecol 1979; 135(8):1021-1024.

    (11)    Kaufert PA, Gilbert P, Tate R. Defining menopausal status: the impact of longitudinal data. Maturitas 1987; 9:217-226.

    (12)    Mansfield PK, Carey M, Anderson A, Barsom SH, Koch PB. Staging the menopausal transition: data from the TREMIN Research Program on Women's Health. Womens Health Issues 2004; 14(6):220-226.

    (13)    Dennerstein L, Dudley EC, Hopper JL, Guthrie JR, Burger HG. A prospective population-based study of menopausal symptoms. Obstet Gynecol 2000; 96:351-358.


Life Phase: 
Updated Date: 
April 14, 2017

Estrogen’s Storm Season: Stories of Perimenopause

Estrogen's Storm Season

by Dr. Jerilynn C Prior

New second edition available

Estrogen’s Storm Season is now available in BOTH print and eBook (Mobi and ePUB) versions!

All royalties are recieved in our Endowment fund (overseen by UBC) and support CeMCOR's research and future.

It is full of lively, realistic stories with which women can relate and evidence-based, empowering perimenopause information. It was a finalist in 2006 for the Independent Publisher Book Award in Health.

Purchase your ebook copy via our Amazon Kindle or
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Paperback copies (with updated insert) still available here.

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