Most women experience vaginal bleeding in the form of their period each month. However, there are other types of vaginal bleeding too, including abnormal uterine bleeding (AUB) and bleeding between periods, which you may be a little more concerned about. Below, you can find out more about vaginal bleeding, including some of the causes and how to treat them.


Causes of vaginal bleeding


A period

A period is one of the main causes of vaginal bleeding, and most women will get their period every 28 days or so, though cycle length can vary from 21 days up to 40 days, and this is still considered normal.

A period is the endometrial lining of the uterus shedding when a fertilised egg hasn’t been implanted in the uterine wall (i.e. you’re not pregnant). The bleeding can last on average between three to seven days and in this time, a woman will lose around 75 millilitres of blood. Between the ages of 12 and 52, the average woman could have around 480 periods.

While your period can sometimes be hard to track, particularly if you have irregular periods, this type of bleeding isn’t anything to worry about.

You may, however, have particularly heavy periods. A very heavy period is one that lasts for more than seven days, results in bleeding through tampons and pads or causes clots that are bigger than three centimetres in diameter. You may also be showing signs of anaemia, including fatigue and light-headedness. When this is the case, a heavy period is known as menorrhagia. This can sometimes be caused by polyps or fibroids, both of which we cover separately below.


Hormonal contraceptives

Hormonal changes and hormonal imbalances can lead to AUB. There can be a whole host of reasons as to why your hormones have changed or become unbalanced.

If you have recently switched to a new form of hormonal contraception, then it’s fairly common for you to experience some sort of bleeding between your periods. This is particularly the case if you use the combined pill, progestogen-only pill, contraceptive patch, implant, injection or intrauterine system (IUS). It’s likely that your body is adjusting to the change and the symptoms should settle down within a few months. If bleeding is frequent, heavy or prolonged or if you are worried about any changes to your periods you should seek medical advice. A doctor may suggest you try another form of contraception.

You can also experience bleeding between periods if you’ve missed a pill, have had sickness and/or diarrhoea while on the pill or have problems with your patch/vaginal ring.

Interestingly, birth control can sometimes be used to treat AUB, depending on the cause.


Polycystic ovary syndrome (PCOS)

PCOS is a condition that impacts how your ovaries work and affects approximately one in 10 women in the UK. The syndrome can result in fluid-filled sacs that surround the eggs in the ovaries, preventing ovulation from taking place, and it can also cause increased levels of male sex hormones. This is why some women with PCOS have increased facial and body hair. Other symptoms of the syndrome are irregular periods or no periods at all.

There is currently no cure for PCOS, and even some confusion around what causes it, but the symptoms can be treated.  For instance, the contraceptive pill can be taken to regulate periods and prescription creams can slow the hair growth on your face and other areas.



Polyps are small benign growths that can develop on the cervix or in the uterus. Cervical polyps are most common in women who have birthed children vaginally, and most may not even know they have them. There are very few symptoms, but occasionally they can cause AUB.

The removal of polyps can be quite straightforward with little pain, particularly if they’re small. Local anaesthetic may be required for larger polyps, though the recovery period is still relatively painless.



Occasionally, unexpected bleeding or spotting can be a potential sign of pregnancy. If you’ve missed a period recently or have reason to believe you might be pregnant, it could be worth taking a test.

Vaginal bleeding is thought to occur in around one in three pregnancies. Light bleeding at the start of a pregnancy could be caused by the fertilised egg implanting into the uterus lining (known as implantation bleeding), but heavier bleeding could also be a sign of a spontaneous miscarriage or an ectopic pregnancy. When it occurs in the second and third trimesters, it could be caused by placenta previa or placental abruption. If you are pregnant or think you could be pregnant and you experience any vaginal bleeding you should urgently talk to your midwife or doctor.


Sexually transmitted infections (STIs) 

Not all STIs have the same symptoms, but some, such as chlamydia, can cause unusual vaginal bleeding. The bleeding can come in the form of spotting between periods, but you may also find that you’re bleeding during or after sex.

Chlamydia can usually be treated with antibiotics, and you’ll likely find that your symptoms clear up quite quickly once you’ve started the treatment. Your sexual partners may also need to seek treatment.



The menopause is something nearly all women go through. As we age and our oestrogen levels begin to drop, we can experience symptoms like hot flushes, mood swings and brain fog. Irregular periods can also be a common symptom.

A woman is thought to have been through the menopause when she hasn’t had a period for a full 12 months. The time period before this, though, when symptoms like the above occur but she still has some periods, is known as the perimenopause. This starts for most women between the ages of 45 and 55, and can last as long as 10 years, though for many people, it doesn’t last as long as this.

For women going through the perimenopause, the vaginal bleeding that occurs is part of your normal menstruation, but you may find it difficult to track your cycle.


Cancers of the reproductive system

While it may be unlikely, there are certain cancers of the reproductive system that could be causing unusual vaginal bleeding. If the bleeding is caused by cancer, it could be due to cervical, uterus or vaginal cancer.

If you are aged 25 to 64, you should go for regular cervical cancer screenings. Currently, these are offered every three years until you reach the age of 50, when they are offered every five years. The test can show up any abnormal cells, which can then be investigated further. The screening helps to ensure that cervical cancer is found earlier rather than later.

Womb or uterus cancer is more common in post-menopausal women, and endometrial cancer is more common in women aged 50 and over.  


If you’re concerned about AUB, bleeding between your periods or very heavy periods, you should seek medical advice. A healthcare professional may perform some tests, depending on what they think the reason for the bleeding is. These tests could include an STI screening, a pregnancy test, a cervix examination, a pelvic ultrasound scan or a cervical cancer screening.




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