Symptom · Cycle changes
Your period doing whatever it wants. Length, flow, timing — pick any three.
A 21-day cycle, then a 45-day one, then two weeks of spotting, then a flood, then nothing for three months, then a week-long soak that feels like your twenties on a bad month. The shape you built a life around for thirty years has quietly gone off-piste, and nobody told you this is the shape of perimenopause, not a warning sign.
Educational · not medical advice
Cycle chaos is often the very first thing that shifts. Ovulation stops being predictable; estrogen swings higher and drops steeper; progesterone (which only shows up after ovulation) becomes patchy. The result is a cycle that shortens first, then starts to skip, then can flood or drag on, all within the same year. This is the STRAW+10 map of perimenopause working exactly as described — not a personal failure and not usually a sign of anything wrong. The job on this page is to help you tell 'this is peri' from 'this is peri plus something else' (fibroids, polyps, thyroid, PCOS/PMOS, a bleeding disorder, or, after twelve months of no period, postmenopausal bleeding — which is always worth a workup).
Why this is happening now
Three overlapping shifts, in roughly this order, over several years.
- 01
Cycles shorten first
In early perimenopause the follicular phase (day 1 to ovulation) usually shortens, so cycles run 21–24 days instead of 28. Same amount of period, arriving faster. This is the STRAW+10 'early transition' stage — the earliest and most reliable signal that peri has started, often years before flashes.
- 02
Then cycles start to skip, and flow gets unpredictable
As ovulation becomes patchy, cycles start to skip — 45 days, then 60, then a normal one, then another skip. When you don't ovulate, progesterone doesn't rise, so the endometrium can build unopposed by estrogen and shed as a heavier or longer period when it finally goes.
- 03
Estrogen swings high, low, and back — often on the same cycle
Perimenopause is not a slow slide down. Estrogen often spikes above premenopausal levels, then drops steeply — the same rollercoaster that drives migraine, breast tenderness, and mood shifts on top of the bleeding chaos. This is why 'my hormones are declining' is the wrong picture; 'my hormones are unpredictable' is closer.
- 04
The 12-month rule for menopause
Menopause is defined as twelve full months with no bleed of any kind. Any bleeding before that clock resets it. Any bleeding after that clock is postmenopausal bleeding (PMB) and always warrants a workup — usually benign, but always investigated.
- 05
You can still get pregnant
Ovulation is patchy but not absent — pregnancy is possible until you've had twelve months with no period (or 24 months if you're under 50 in some guidelines). If pregnancy is not the plan, contraception still matters. The Mirena, in particular, doubles as HRT progestogen and contraception, which is why it's so useful in this window.
What tends to help
You can't smooth the underlying chaos, but you can make it manageable and know when to push.
Track it — badly is fine
Any period-tracking app or a paper calendar. Two data points a day: is there bleeding, and how heavy (spotting / normal / heavy / flooding). Three to six months of light notes tells a doctor more than any single blood test and makes conversations far more concrete.
Skip the FSH test to 'confirm perimenopause'
FSH swings from cycle to cycle in perimenopause and a normal result does not rule peri out. Both major menopause societies (NAMS/Menopause Society, IMS) explicitly say diagnosis in women over 45 is clinical, not biochemical. Save the bloods for ruling out other things — thyroid, iron, prolactin — where they actually change the plan.
For heavy or flooding bleeds, name the tools
Tranexamic acid (taken only on heavy days) reliably cuts flow by 30–50%. The Mirena IUS reduces bleeding dramatically over 3–6 months and doubles as HRT progestogen. Endometrial ablation, myomectomy or (rarely) hysterectomy are further along the same shelf. See the heavy bleeding guide for the full menu — you do not have to just cope.
For long dragging bleeds, iron matters
Chronic slow bleeding is the classic route to iron-deficiency anaemia in midlife women, and low ferritin is often what's actually behind the exhaustion, hair thinning and restless legs. Ask for a ferritin, not just haemoglobin. Aim for ferritin above 50; below 30 warrants supplementation and often an infusion.
3 more practices, plus podcasts, books and research, live in Go deeper below.
03When to get help nowWhen it's not just peri
Emergency red flags, same-week signs, and where to find a menopause-trained practitioner.
When it's not just peri
5 more signs it needs a doctor this week
Flooding — soaking a pad or tampon an hour, for several hours
This is heavy menstrual bleeding by definition and warrants a proper workup: ultrasound, blood count, ferritin, and a conversation about tranexamic acid or Mirena. See the heavy bleeding and fibroids guides.
Bleeding between periods, or after sex
Intermenstrual bleeding and postcoital bleeding both deserve a proper look — usually polyps, cervical friability from GSM, or fibroids, occasionally something more. Not a 'wait and see'.
Any bleeding after twelve months of no periods
Postmenopausal bleeding is always investigated. Ultrasound of the endometrial lining plus (usually) a biopsy is the standard first pass. Overwhelming majority is benign; the reason we investigate every single episode is that when it's endometrial cancer, catching it early changes everything.
Cycles that shortened dramatically before age 40
Menstrual changes before 40 can be early perimenopause — normal for many women — but also warrant an FSH and estradiol at day 2–5 of a cycle, twice, four weeks apart, to check for premature ovarian insufficiency (POI). Not the standard peri workup; the POI conversation is different and needs bone/cardiovascular protection sooner.
Cycles have been chaotic for years and you feel dismissed
'It's just your age' is not a plan. A menopause-trained doctor plus, if needed, a gynaecologist, is the room for it. The bar for a proper conversation about symptoms + MHT + IUS + contraception is not high, and you should not be normalising something you're miserable about.
Go deeper
One place for everything else.
Practices to try this week, voices worth hearing, books worth your bedside table, rooms where members are talking, the candid tips Nila would share over a cup of tea, and the research the editorial team is watching.
Cycle length, one line per bleed
First day of bleed to first day of the next. Three months of data usually shows the shortening/skipping pattern clearly.
Heaviness on the heaviest day
Rough categories are fine: 'a normal day', 'through clothes/sheets', 'soaking a pad or tampon every hour or less'. That last one is the flooding threshold that changes the medical conversation.
Any bleed after twelve full months without one
This is the single most important line on the page. Any bleeding at all after twelve months of no period is postmenopausal bleeding and needs a workup — usually benign (atrophic endometrium, polyps, GSM), but always investigated. Do not wait it out.