Irregular periods in perimenopause: when your cycle stops making sense
Shorter, longer, heavier, skipped. Why periods change in perimenopause, what's typical, which bleeding needs checking, and what helps.
For years your period arrived like clockwork. Now it turns up after three weeks, then vanishes for two months, then arrives heavier than you've ever known. You're buying pads 'just in case' and wondering whether this is normal or something to worry about.
Irregular periods in perimenopause are often the very first sign that things are changing, sometimes years before hot flushes or other symptoms. This article explains why your cycle changes, what's typical, which bleeding patterns need checking, what helps, and what you need to know about contraception.
The short answer: in perimenopause, you stop ovulating every month, so the balance between oestrogen and progesterone becomes unpredictable. Periods may come closer together at first, then further apart, and can be heavier, lighter or skipped altogether. Very heavy bleeding, bleeding between periods or after sex, and any bleeding after your periods have stopped should always be checked.
Why periods change in perimenopause
Your cycle is run by a hormonal conversation between your brain and your ovaries. Each month, oestrogen builds up the lining of your womb, and after you ovulate, progesterone steadies it. When you don't get pregnant, both hormones drop and the lining sheds as your period.
In perimenopause, your ovaries start to run low on eggs and ovulation becomes less regular. In months when you don't ovulate, you make little progesterone, while oestrogen can swing high or low. The womb lining may build up more than usual and shed unpredictably, which is why periods can become heavier, longer or erratic.
Many women notice their cycles get shorter first, with periods coming every three weeks instead of four. Later, gaps between periods tend to get longer, with skipped months becoming more common as you get closer to menopause. Menopause itself is when you haven't had a period for 12 months in a row.
Your cycle isn't broken. It's changing gear, and knowing the difference between typical and unusual changes is what keeps you safe.
What's normal with irregular periods in perimenopause
Every woman's pattern is different, but these changes are common in perimenopause:
Shorter or longer cycles. Your cycle may shrink to three weeks, then stretch to six weeks or more.
Skipped periods. You might miss one or several months, then have a period again. This can go on for some time before your periods stop for good.
Heavier or lighter flow. Some periods may be much heavier than you're used to, with small clots, while others are light.
Worse premenstrual symptoms. Breast tenderness, bloating, mood swings and headaches before a period can become stronger. Our guide Perimenopause rage, tears, and everything in between covers the mood side.
Changes in your periods often come alongside other symptoms, such as hot flushes, broken sleep and brain fog. Our guides Perimenopause hot flushes: what's happening, and what actually helps and Why you're wide awake at 3am in perimenopause cover two of the most common.
When to see a doctor about perimenopause bleeding
Changing periods are expected, but some bleeding patterns need checking, whatever your age. Other conditions such as fibroids, polyps, thyroid problems and pregnancy can cause similar changes. Rarely, abnormal bleeding can be a sign of changes in the womb lining, including womb cancer, which is why it's important not to ignore it.
See your GP if you have:
Very heavy periods. For example, needing to change your pad or tampon every one to two hours, passing clots larger than about 2.5cm (the size of a 10p coin), bleeding for more than seven days, or bleeding through your clothes.
Bleeding between periods or after sex. This should always be checked, even if it's light.
Periods much closer together. Periods that come more often than every three weeks, or that change pattern suddenly, are worth discussing.
Signs of low iron. Feeling very tired, breathless, dizzy or looking pale can mean heavy bleeding has caused anaemia.
Any bleeding after menopause. If you bleed after 12 months without a period, see your GP promptly. If you're on HRT and have unexpected bleeding, especially after the first few months, tell your doctor.
Get urgent help from NHS 111, or call 999 in an emergency, if you're soaking through pads every hour for several hours, or you feel faint, very dizzy or short of breath.
If you're over 45 and have typical symptoms, you usually don't need a blood test to diagnose perimenopause. Your GP may suggest a blood test to check for anaemia or thyroid problems, a pregnancy test, or a pelvic ultrasound if bleeding is unusual.
What helps with irregular and heavy periods
Track your cycle. Note the first day of each period, how many days you bleed, how heavy it is and any other symptoms. After three months, you'll have a clear picture of your pattern, which is one of the most useful things you can take to an appointment.
Be prepared. Keep period products in your bag, at work and in the car. Period pants or a menstrual cup can give extra protection on heavy days, and darker clothes can take the worry out of a surprise bleed.
Look after your iron. If your periods are heavy, eat iron-rich foods such as red meat, beans, lentils and leafy greens. If you think you might be low, ask your GP for a blood test before taking iron tablets.
Treatments for heavy periods. Your GP can offer effective options, including a hormonal coil (IUS), which often makes periods much lighter and also works as contraception, tranexamic acid tablets taken during your period, anti-inflammatory painkillers, or hormonal tablets. If these don't help, there are specialist treatments too.
HRT. If you have other perimenopause symptoms, HRT can help. While you're still having periods, it's usually given in a form that gives you a regular, predictable monthly bleed. Irregular bleeding is common in the first few months of starting HRT. Our guide HRT for perimenopause in 2026: a calm look at the evidence sets out the benefits and risks.
Keep using contraception. You can still get pregnant in perimenopause, even with irregular periods. NHS advice is to keep using contraception until you've had no periods for two years if you're under 50, or for one year if you're over 50. HRT is not a contraceptive. Our guide How to talk to your doctor about perimenopause can help you raise all of this at one appointment.
Frequently asked questions
### 1. Is it normal to have irregular periods in perimenopause?
Yes. Irregular periods are one of the most common signs of perimenopause, often starting in your forties. Cycles may get shorter, then longer, and you may skip months. But bleeding between periods, after sex, very heavy bleeding or bleeding after menopause isn't a normal part of the change and should always be checked.
### 2. Can you get pregnant during perimenopause?
Yes. Even if your periods are irregular, you may still ovulate some months, so pregnancy is possible. NHS advice is to use contraception until you've gone two years without a period if you're under 50, or one year if you're over 50. HRT doesn't work as contraception, so you'll need a separate method.
### 3. Are heavy periods with clots normal in perimenopause?
Heavier periods and small clots are common in perimenopause. But see your GP if you're changing protection every one to two hours, passing clots bigger than a 10p coin, bleeding for more than a week, or feeling tired and breathless. Heavy bleeding can cause anaemia and is very treatable.
### 4. Can perimenopause cause spotting between periods?
Hormonal changes can cause light spotting, but bleeding between periods can also be caused by polyps, infection or changes in the womb lining. It's always worth getting spotting between periods or after sex checked by your GP, even if it's light and you feel well otherwise.
### 5. How long do irregular periods last before menopause?
It varies. For many women, irregular periods last a few years before they stop completely, but it can be shorter or longer. Periods usually become further apart as you approach menopause. You've reached menopause when you haven't had a period for 12 months in a row.
Your next step
Irregular periods in perimenopause are common, and most changes are part of the transition. The most useful thing you can do is track your cycle for the next three months: start date, length, flow and any bleeding between periods. It gives you peace of mind and gives your GP the facts if you need an appointment.
If you'd like to see whether your cycle changes are part of a bigger picture, take our three-minute symptom check-in. You'll get a summary to take to your GP. And for calm, practical guidance in your inbox, join our weekly email: one letter a week, nothing you didn't ask for.
This article is general information, not personal medical advice. If you're worried about changes in your periods or any bleeding, please speak to your GP.
Very heavy bleeding, bleeding between periods or after sex, and any bleeding after menopause should always be checked, whatever your age.
