Knowing what’s normal: irregular bleeding and perimenopause

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Perimenopause is the period of time leading up to the menopause, when the ovaries start to produce less oestrogen. This occurs at variable times in different women. In general, it often starts in women during their 40s, but very occasionally it can start before the age of 30. Perimenopause can last from a few months to 10 years, and lasts an average of 4 years, ending when the menopause occurs – when the ovaries have stopped releasing eggs completely and when a women has gone a year without any menstruation.

During perimenopause there is a rapid decline in oestrogen production, especially in the last two years. The ovaries function erratically and unpredictably, sometimes releasing eggs and sometimes not. It is at this stage that many women experience the uncomfortable symptoms associated with perimenopause such as hot flushes, breast tenderness, low sex drive, fatigue, vaginal dryness, and mood changes. These symptoms happen because of the haphazard fluctuation in oestrogen and fall in progesterone. Not all women will experience symptoms, however, because some women have a gradual decline in hormones rather than the erratic fluctuations.

Menstrual bleeding during perimenopause – what can it be like?

During perimenopause, irregular periods are common. This is often normal and is rarely any cause for concern. It occurs because the regular pattern in the rise and fall of oestrogen and progesterone is disrupted and there is now an unpredictable fluctuation in hormones during the menstrual cycle. As a result there are a variety of different menstrual changes that may occur. Cycles may be shorter than usual or bleeding can be days to weeks late. Periods can be heavier, or lighter, or vary a lot between each cycle.

Short menstrual cycles occur when there is a very low oestrogen level compared with progesterone. This is because oestrogen helps cause the womb lining to thicken, so when the levels are low, there is less lining to shed, hence the periods become short or scant. When there are more fluctuations in oestrogen and progesterone levels with lots of peaks and troughs, periods may be more frequent.

When menstrual cycles are prolonged, this is due to high oestrogen levels compared to progesterone levels. If ovulation does not occur, progesterone is not produced, so there is subsequently no sharp drop in progesterone, the trigger for the womb lining to be shed. Therefore you may experience a missed period, only for your period to be particularly heavy when it does arrive.

Towards the end of perimenopause, your periods may be very late and then you may have several skipped periods before they stop altogether. This is due to the gradual decline in oestrogen production by the ovaries. During perimenopause, then, periods may be very unpredictable, and this is very normal.

When may irregular bleeding during perimenopause be due to something else?

The quantity and frequency of periods can vary so widely during perimenopause that it may be difficult to know if there is anything else underlying. If your irregular periods, which may be heavy, are accompanied by tummy pain in the pelvis or lower abdomen, discomfort during sex that’s felt deep inside the lower tummy, stinging pain on passing urine, or unusual yellow or green vaginal discharge, then this could be due to a pelvic infection known as pelvic inflammatory disease (PID). This condition is caused by bacteria such as chlamydia or gonorrhoea, spread from the vagina or cervix. PID may respond to treatment with antibiotics and so if you experience any of these symptoms in addition to irregular periods then it is important to seek advice from your GP.

Any bleeding after menopause, even if it’s spotting, is abnormal and you should see your GP or gynaecologist. One common cause of spotting after menopause is endometrial atrophy. The levels of oestrogen are very low after menopause and, as a result, the womb lining becomes very thin. As the lining thins, abnormal bleeding occurs.

Another common cause of heavy bleeding after menopause is endometrial hyperplasia, although it can occur during perimenopause. The menstrual cycle may be longer or shorter than usual, and a change in menstruation may be the only symptom of endometrial hyperplasia. This condition occurs when the womb lining is too thick because there is an excess of oestrogen without progesterone. Although it is not cancerous, endometrial hyperplasia can lead to cancer of the uterus in some cases. This is because there is so much rapid growth of the endometrial lining, so some of the cells may become abnormal. If this condition is suspected your GP may refer you for an ultrasound and a tissue sample to be taken of the womb lining. Therefore seek advice from GP if your periods become very heavy, especially if occurring after menopause.

Sometimes small non-cancerous growths in the womb lining, called polyps, may cause abnormal bleeding during perimenopause and after menopause. This bleeding may be excessively heavy, or take the form of bleeding between periods, or after sex. There are no other associated symptoms. This bleeding occurs because the polyps are very prone to bleeding.

Heavy or painful periods associated with lower tummy pain, back pain, frequent peeing, constipation, or pain during sex may be due to fibroids, although many women may have fibroids without any symptoms at all. Fibroids are non-cancerous growths made up of muscle and fibrous tissue found in or around the uterus, and the exact cause is unknown. Fibroids tend to be less of a problem after menopause because fibroids shrink when oestrogen levels are low.

These are just a few common conditions that may cause abnormal bleeding during perimenopause. Always seek advice from your GP if you are particularly concerned about abnormal menstrual bleeding during perimenopause, because it can be difficult to know if it is all due to normal changes. In particular, it is important to seek medical advice if the bleeding is very heavy, or lasts longer or shorter than normal, and especially if there is bleeding after sex or between periods.

Dr. Diana Chiu MBChB (Hons), MRCP, PGCERT (Med Ed), PhD

Diana received her medical degree, with honours, from the University of Manchester. She then went on to receive basic and specialist medical training within the north west of England. She carried out in-depth research in medicine and was awarded a PhD in 2016. Currently, she is finishing her medical training at a large teaching hospital, and one of her greatest interests is medical education. She is an advanced life support instructor and writes regularly for post-graduate examination websites, and also holds a PGCERT in medical education with distinction.

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