There are several things that could cause bleeding between periods, such as changes to your hormonal levels, use of hormonal contraception or contraceptive devices, an infection, or an injury, for example.

Bleeding between periods should be checked out by your doctor. You should also go to your doctor if you bleed after sex.

Changes to your hormonal levels

Young women often spot, or bleed very slightly, when they ovulate (release an egg from the ovary). It happens about 10-14 days after their period and is usually caused by a temporary drop in levels of the hormone oestrogen. This is quite normal.

As well as reduced oestrogen levels, you may also experience other hormonal imbalances, which are completely harmless. This could be as a result of stress, or a recent change of diet. Your doctor will be able to diagnose this by talking to you, and possibly taking a blood sample, and also advising you about possible treatments.

Girls who have just started their periods and women going through menopause are more likely to have irregular periods.

Use of hormonal contraception

If you have recently started taking hormonal contraceptives it is not uncommon to experience bleeding between periods due to the drop in hormone levels. This will usually happen around two weeks after your last period, and is often referred to as breakthrough bleeding.

Your periods will usually become more regular within six months, and the bleeding between your periods should stop after a month or two. Bleeding between periods can also occur if you forget to take one of your oral contraceptives.

However, if bleeding occurs at other points during your menstrual cycle, you should consult your doctor in order to rule out the possibility of other conditions.

If you have other hormonal contraceptives such as hormone containing intra-uterine devices (IUDs) contraceptive injections or rods you may have some changes to your bleeding pattern. Many women have heavier, longer and more painful periods. This may improve over time.

If you have prolonged bleeding it may be possible for your doctor to give you additional medicine that can help control the bleeding. They may also check the bleeding is not due to other causes such as infection.

Fertility treatments

Vaginal bleeding may occur during certain fertility procedures - for example, during the egg collection stage of IVF treatment. Usually it is mild to moderate bleeding with some cramping. However, if you experience heavy bleeding, you should contact your fertility clinic or doctor for advice.

Other causes

Bleeding between periods can also be caused by other conditions including:

• endometriosis
• polyps (growths) in your uterus or cervix
• inflammation of your cervix
• abnormalities in the cervix or uterus
• fibroids
• an ectopic pregnancy or the start of a miscarriage
• cancer

When to seek help

If you are bleeding very heavily or you feel faint or that you might pass out, call triple zero (000) immediately and ask for an ambulance. If calling triple zero (000) does not work on your mobile phone, try calling 112.