Irregular Periods

Menstruation, or periods, is the monthly shedding of the lining of the womb.

Periods are part of the female reproductive cycle. They start during puberty (between the ages of 10 and 16) and continue until the menopause (45 to 55). The average menstrual cycle lasts 28 days, but can vary between 24 and 35 days.

It can take up to two years for periods to settle into a regular cycle. After puberty, most women develop a regular menstrual cycle, with around the same length of time between periods.

Menstrual bleeding normally lasts between two and seven days, with the average being five days.

However, some women have an irregular menstrual cycle. This is where the time between periods, the amount of blood lost and the number of days bleeding lasts all vary widely.

Why are periods sometimes irregular?

The pattern of a woman's menstrual cycle can be disturbed by a change in contraception method. It could also be affected by an imbalance of the hormones oestrogen and progesterone, which regulate the menstrual cycle. Many factors can cause a hormone imbalance (see Causes).

Irregular periods are common during puberty or nearing menopause. Treatment during these times is usually not necessary.

Causes of irregular periods

The pattern of a woman's menstrual cycle can be disturbed by:

• changing the contraception method, or
• an imbalance of the hormones oestrogen and progesterone, which regulate the menstrual cycle.

There are several factors, outlined below, which can cause a hormone imbalance.

Polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) occurs when many cysts (small, fluid-filled sacs) develop in the ovaries. The usual symptoms of PCOS are irregular or light periods, or no periods at all.

This is because in PCOS, ovulation (the releasing of an egg) often does not take place. Also, the production of hormones may be unbalanced, and you could have higher levels of testosterone (a male hormone that women have a small amount of) than normal.

For more information, go to the polycystic ovarian syndrome page.

Lifestyle

The following factors can upset your balance of hormones and cause irregular bleeding:

• extreme weight loss or gain,
• heavy exercise, or
• stress.

Age

It is not unusual to have a hormone imbalance for a few years after puberty and before the menopause, which can cause irregular bleeding. The menstrual cycle may become longer or shorter and/or the periods may become lighter or heavier.

Another reason for irregular periods around puberty and the menopause is that the ovaries are not producing an egg every month.

Gynaecological problems

Irregular bleeding can also be due to unsuspected pregnancy (see box), early miscarriage or disorders (problems) of the womb or ovaries.

Thyroid disorders

A thyroid disorder is another possible cause of irregular periods (the thyroid gland produces hormones that maintain the body's metabolism). The doctor may test for a thyroid problem by checking the levels of thyroid hormones in the blood. For more information, go to the overactive throid page.

Contraceptives

An intrauterine device (IUD) or contraceptive pill may cause spotting between periods. An IUD can cause heavy bleeding.

Small bleeds, known as breakthrough bleeds, are common when the contraceptive pill is first used. They are normally lighter and shorter than normal periods, and usually stop within the first few months.

Cancer

Bleeding when you have sex or heavy bleeding between periods could be a symptom of cancer of the cervix or womb, although this is rare. This can be diagnosed by examination and biopsy. Tests may include colposcopy, direct examination of the vagina and cervix and a pelvic scan.

For more information, go to the page on cervical cancer and cancer of the womb.

Treating irregular periods

Irregular periods are common during puberty or nearing menopause and treatment is usually not necessary.

If treatment is necessary, the type of treatment will depend on the reason for your irregular periods.

Changing your method of contraception

If you have recently been fitted with an intrauterine device (IUD) and you are experiencing irregular bleeding that does not settle within a few months, discuss changing to another method of contraception with your GP or practice nurse.

If you have started taking a new contraceptive pill that is causing irregular bleeding, you may be advised to change to another type of pill.

Treating polycystic ovarian syndrome

For overweight women with polycystic ovarian syndrome (PCOS), the symptoms can be improved by losing weight, which will also help with irregular periods. If you lose weight, your body does not need to produce as much insulin, which reduces testosterone levels and improves the chance of ovulation (releasing of the egg each month).

Other treatments for PCOS include anti-male hormone drugs and other hormone treatment. For more information, see Treating polycystic ovarian syndrome.

Treating thyroid problems

Treatment for an overactive thyroid gland involves:

• medicines that slow down the production of thyroid hormones,

• radioactive iodine therapy, or

• surgery to remove part of the thyroid gland

The menstrual cycle should return to normal after these treatments. If it does not, go back to your GP.

Counselling and stress management

Stress or sudden weight loss may be diagnosed as a cause of irregular periods. Relaxation techniques, stress management or counselling (talking to a therapist) may be recommended.