Irregular cycles (chaos, skips, floods)

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.

Three overlapping shifts, in roughly this order, over several years.

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.

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.

Estrogen swings high, low, and back — often on the same cycle. Perimenopause isn't 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.

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.

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.

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 doesn't rule peri out. Both major menopause societies (NAMS/Menopause Society, IMS) explicitly say diagnosis in people 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 MHT progestogen. Endometrial ablation, myomectomy or (rarely) hysterectomy are further along the same shelf. See the heavy bleeding guide for the full menu — you don't have to just cope.

For long dragging bleeds, iron matters. Chronic slow bleeding is the classic route to iron-deficiency anaemia in midlife people, 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.

For unpredictable timing, plan for surprise, not for schedule. A period-kit in your bag, in the car, at your desk, at your parents'. Menstrual underwear for the days you don't quite trust yourself. Dark bedding for a while. Not glamorous, quietly effective.

MHT can regulate the picture, especially with a Mirena. For people in perimenopause who are still cycling erratically, a low-dose estrogen patch or gel paired with a Mirena (or cyclical oral progesterone) often calms both the bleeding chaos and the surrounding symptoms. This is a conversation for a menopause-trained doctor, not a rushed 8-minute GP slot.

Check the thyroid and PCOS/PMOS picture at least once. Both thyroid disease and PCOS/PMOS can mimic or overlap with peri cycle chaos, and both are common in midlife people. A TSH + free T4, and a testosterone/SHBG if the PCOS picture fits, is a cheap, one-time ask.