My period every 15 days, then nothing: this is perimenopause

What you're living is documented, not imagined. More than 9 in 10 women have cycle changes (length, flow, frequency) during this transition ^[1]. You're in the overwhelming majority.

Menopause is a single point: twelve months in a row with no period. Perimenopause is the whole journey before it, when your ovaries start working in fits and starts ^[2]. The average age of menopause is 51, within a 45 to 55 range ^[2]. Perimenopause itself often begins in your early 40s.

Researchers have set clear markers. When the gap between your periods varies by 7 days or more from one cycle to the next, you're in early perimenopause ^[3]. When you start skipping more than 60 days with no period, you're nearing the finish line ^[3].

Good news: after 45, this can be diagnosed from your symptoms and cycle changes, with no routine blood test ^[4].

At the root: your ovaries hold fewer and fewer eggs, and respond less to the brain's signals ^[2]. To compensate, the brain sends more FSH. Sometimes an egg matures too fast, and your period arrives after just 15 to 20 days ^[2].

Other months, no egg matures: no ovulation, so no progesterone. That's the hormone that calms and stabilises the uterine lining ^[5]. Without it, estrogen thickens the lining unchecked. When it finally sheds, the bleed is longer and heavier, often after weeks of silence ^[5].

Against all expectation, estrogen doesn't drop in a straight line. It sometimes spikes very high, then crashes, on no visible logic. That instability, not a steady decline, is what makes your cycles unpredictable. Your body isn't betraying you: it's moving through a very real patch of turbulence.

The transition lasts 4 to 8 years on average, with a median around 4 years ^[2][3]. That's long, but there's a real end: menopause is only confirmed after 12 months in a row with no period ^[2].

One thing that matters day to day: ovulation can happen without warning. Pregnancy stays possible until you've gone 12 months with no period (24 months before age 50) ^[10]. If you don't want to conceive, you still need contraception.

You're not stuck just enduring this. Several options can regulate the cycle and calm the bleeding, to choose with your doctor based on your age and history:

• The hormonal IUD (levonorgestrel coil): it strongly reduces heavy bleeding, more effectively than oral treatments, and doubles as contraception ^[9].
• The combined pill: it regularises the cycle, for women without cardiovascular risk factors (non-smokers, no history of clots) ^[2].
• Progestogen-only therapy: it makes up for the progesterone this phase is missing ^[2].
• Tranexamic acid: a non-hormonal medicine, taken only on heavy-bleeding days, that cuts blood loss by 30 to 60% without changing your cycle ^[8].

Not all of it is "just the hormones," and checking is a move of control, not panic. Alongside the hormonal chaos, structural causes exist.

Doctors use a classification (PALM-COEIN) that separates physical causes from purely hormonal ones ^[6]. Physical causes include a polyp (a small growth inside the uterus) and a fibroid (a benign tumour of the uterine muscle). Adenomyosis is another one: lining tissue that grows into the wall of the uterus ^[6].

These are common and usually benign. Up to 8 in 10 women develop a fibroid before menopause, often without knowing ^[7]. But when bleeding is abnormal, it's worth checking.

A pelvic ultrasound (a simple, painless scan) can spot or rule out these causes ^[8]. If a doctor waves off your prolonged or very heavy bleeding, you're allowed to insist on an ultrasound.