Missed Periods

Why have I missed a period?

There are certain times when it is normal not to have periods. These include:

Before puberty

Girls start to go through puberty from around the age of 9 years and their periods start a year or two later. Up until that point girls do not have periods.

During pregnancy

If you are pregnant, your periods will normally stop until after the baby is born.

During breastfeeding

If you are fully breastfeeding, you will normally not have a period until you stop. You may find you have a bleed if you drop a feed, or start to breastfeed less.

Not having periods due to breastfeeding is called 'lactational amenorrhoea'. It can sometimes be used as a 'natural' contraceptive method, but only works under certain circumstances. See the contraception after having a baby leaflet for more.

After menopause

The menopause is the time in your life when your ovaries stop producing eggs and you stop having periods. The average menopause is around the age of 51. You will be classed as having gone through the menopause a year after your last period. However, it is extremely common for your periods to become less regular in the years leading up to the menopause. See the separate leaflet called Menopause (including HRT) for more details.

There are also lots of other situations where periods can stop, such as:

If you are using certain types of contraception

Some types of contraception (birth control) may stop periods. They do not do so in all women; however, it is normal not to have periods (or to have very light periods) if you are using:

• The contraceptive progestogen-only pill (POP, or mini-pill).
• The intrauterine system (IUS) - sometimes called a coil.
• A progestogen contraceptive injection.
• A progestogen contraceptive implant.
• The combined oral contraceptive pill (COCP), if you are taking it continuously (without any breaks).
• The traditional way to take the COCP is to take it for 21 days, then have a 7 day break, with a period during the break. However, it's also possible to skip the break, which avoids the period. This is safe and may be more effective than the traditional method.

Stress

Stress affects the chemical messengers called hormones which are released from your brain. These hormones then go on to affect other hormones released from your ovaries which normally trigger your periods. Stress or a sudden shock can stop your periods in this way. Usually if this is the case, they resume naturally over some time.

Low body weight

Losing weight may result in periods stopping. This can occur if your body mass index (BMI) goes below 19. If you have an eating disorder called anorexia nervosa, losing too much weight can result in your periods stopping. It may also happen to athletes, gymnasts, long-distance runners and people who do an excessive amount of exercise.

Polycystic ovary syndrome (PCOS)

PCOS is a common condition which can cause periods to be very infrequent or sometimes stop altogether. Women with PCOS may have other symptoms such as difficulty losing weight, spots (acne) and too much body hair. See the separate leaflet called Polycystic Ovary Syndrome for more details.

Hormone problems

A number of health conditions which affect hormone levels may cause missed periods. This includes:

• A condition where a hormone called prolactin is too high. This is called hyperprolactinaemia. The most common cause of this is a non-cancerous (benign) growth in the brain, called a prolactinoma.
• Conditions affecting a gland in your neck, called the thyroid gland. The thyroid gland produces hormones which may affect periods. If you are producing either too much hormone (hyperthyroidism) or too little (hypothyroidism), your periods may be affected.
• Congenital adrenal hyperplasia. This is a rare inherited condition where steroid hormones of the adrenal glands are not produced normally. There are different forms of this condition but some can lead to absent or infrequent periods.
• Another disorder of the steroid hormones, called Cushing's syndrome.

Genetic problems

Genes are the building blocks of our cells and give us our individual characteristics. Genetic conditions are those which are inherited from our parents or due to abnormal genes. In rare cases, abnormal genes can be a cause of not having periods. In most of these, there will be primary amenorrhoea (ie periods never start).

One example of this is Turner syndrome. In this condition, girls tend to be short, have particular features and have ovaries which do not work properly. They often do not start periods when other girls of their age do. See the separate leaflet called Turner Syndrome for more details.

Other genetic conditions may cause differences in genitals and female organs. For example, in a condition called androgen resistance syndrome, the child has female genitals outside but no female organs on the inside. With no ovaries or womb (uterus), these children will not have periods.

Occasionally babies do not develop normally in the womb before birth and may be born with problems which will prevent periods. For example, rarely a girl may be born without a vagina, or with a blockage in the vagina. Sometimes the first time this is apparent is when she does not start to have periods as expected.

Early menopause

The average time for women's periods to stop in the UK is at the age of 51. However, there is quite a wide range. If periods stop before the age of 40, this is very early and is said to be premature menopause. If periods stop between 40 and 45 years of age, it is called early menopause. At the menopause, periods stop and there are usually other symptoms of menopause such as hot flushes.

Medicines and medical treatment

As discussed above, a number of contraceptive treatments can stop you having periods. Other medicines can affect periods too. Examples are some medicines for schizophrenia (antipsychotic medicines), an anti-sickness medicine called metoclopramide and strong painkillers called opiates.

A number of operations may result in absent periods. For example, after a hysterectomy you will not have periods. A hysterectomy is an operation where the womb is removed. As the blood during a period comes from the womb, you will never have periods again afterwards.

Another operation (called endometrial ablation), which is sometimes done for heavy periods, also causes periods to stop. In this operation the lining of the womb is removed. This is not usually permanent and periods start again in time.

Treatments for cancer, such as radiotherapy or chemotherapy, can also damage the ovaries and result in absent periods. Recreational drugs such as heroin may also cause periods to stop.

Getting back to normal after stopping contraception

When you have been on the combined oral contraceptive (COC) pill or an injection form of contraception, it can take a while for your periods to restart once you stop the contraception. It can take a few months for your body's own cycle to restart and it can take several months before you have a period.

What should I do if I have not started my period?

Girls start their periods at a very variable age. So it may be that your friends have been having periods for a while but you have not. Usually this will be normal variation and nothing to worry about.

Ask your doctor's advice if:

• You are 16 years old or older and still have no periods.
• You are 14 years old or older and have not developed breasts or pubic hair and do not have periods.
• You have a pain in your tummy every month but no bleeding.
• You can feel a lump in the lower part of your tummy.
• You have had sex without using contraception (ie if there is any chance you could be pregnant). It's very helpful to do a pregnancy test first.
• You have lost weight or have symptoms of anorexia nervosa. (See the separate leaflet called Anorexia Nervosa for more details.)
• You feel unwell in yourself in any other way.

Should I see a doctor about a missed period?

Don't panic! In most cases there is nothing serious going on. The most important thing to do is to do a pregnancy test if there is any chance at all you could be pregnant. If you otherwise feel well in yourself, and you are not pregnant, then the chances are your periods will start up again in due course.

You should consult a doctor if:

• You have not had a period for three months and your periods were previously regular.
• You have not had a period for 6-9 months but your periods have always been infrequent.
• You could be pregnant.
• You wish to become pregnant.
• You have hot flushes or night sweats and are under the age of 45.
• You have lost weight or your BMI is 19 or less.
• You or someone close to you is concerned about your eating or weight.
• You have milk leaking from your breasts and are not breastfeeding.
• You feel unwell in yourself (for example, headaches, changes in your vision, have lost or gained weight).
• You have not had a period for six months after stopping the contraceptive pill (or 12 months after the last contraceptive injection).
• You are worried about your lack of periods.

Will I need any tests for a missed period?

If you go to see a doctor about your periods stopping, first of all the doctor will ask you some questions. For example, the doctor will want to know:

• If you have ever had periods and whether they were regular.
• How long you have not had periods for.
• If you have recently been using any contraception.
• If you are on any medication or have any other medical conditions.
• If you have recently lost weight.
• If you are under any stress.
• If there is any chance you could be pregnant.
• If you have any other symptoms, such as hot flushes or milk leaking from your breasts. (Hot flushes may suggest an early menopause; milk leaking from your breasts suggests high levels of the hormone prolactin, discussed above.) The doctor may also ask about signs of pregnancy such as morning sickness or tender breasts.

Your doctor may then wish to examine you. The doctor may want to check your weight and height and then work out your BMI. They may also want to feel your tummy. They may want to look for signs of possible causes. (For example, excess body hair suggesting PCOS, or a lump in the neck suggesting a problem with the thyroid gland.) In some cases an internal examination may be needed.

Whether further tests are needed will depend on what has been discovered from talking to you and examining you. You may not need any tests at all. Tests which may be needed include:

• A pregnancy test (usually checked from a sample of urine).
• Blood tests. These are done to check out a number of possible causes. They may be done to check hormonal imbalances (such as thyroid hormones and prolactin as discussed above, or the levels of hormones coming from the ovary). Occasionally tests for gene abnormalities may be needed.
• An ultrasound scan. (This may be needed to check your internal organs are normal, especially if you and your doctor wish to avoid an internal examination. This might be the case, for example, in young girls who have not started their periods.)

How are absent periods treated?

This depends on the cause. In many cases no treatment is needed. See the specific leaflets about the various causes for information on how each is treated.

Is it dangerous to miss a period?

In the short term, there are no complications of missing a few periods. However, if it goes on for a longer time, it may cause some problems.

Infertility

Women who are not having periods may not be producing eggs from their ovaries (ovulating). This would mean they would not be able to become pregnant naturally. For some women this may be an issue. However, for many causes, there is treatment to help with this, so discuss it with your doctor if you want to become pregnant. See the separate leaflet called Infertility for more details.

Weak bones (osteoporosis)

When the absent periods are combined with low levels of the female hormone oestrogen, there may be a risk of bones weakening. Oestrogen helps keep bones strong, and they start to weaken after menopause. If they become excessively weak and break (fracture) easily, this is called osteoporosis.

This only applies to women who have not had a period for a long time (a year or more). It is particularly a risk for women whose periods have stopped due to early menopause, weight loss, anorexia nervosa or excessive exercise.

Heart disease

It is suspected that low oestrogen levels also put a woman at risk of heart disease. Also women with PCOS are more likely to develop risk factors for heart disease, such as high blood pressure, high cholesterol levels, and diabetes. A healthy diet is particularly important for women with PCOS to reduce the risk.

Thickening of the lining of the womb

Women with PCOS may have irregular, or no, periods, despite having high levels of oestrogen. This combination can cause the lining of the womb to thicken (called endometrial hyperplasia). Over the long-term, having a thickened womb lining can increase the risk of developing cancer of the womb.

Therefore, women with PCOS who have fewer than four periods a year (ie longer than 3 months between periods) are usually offered medicines to produce a period every 3 to 4 months, to stop the womb lining from becoming too thick.

Irregular periods

Other patterns of periods which are different to normal may also occur, as follows.

Infrequent periods

Having periods less often than normal is called oligomenorrhoea. The causes of this are much the same as the causes of absent periods discussed above. The most common cause is PCOS.

Erratic periods

For some women, periods don't happen regularly but seem to come at unexpected times. Some months the gap between periods may be shorter than 28 days and other months it may be longer. This is common in teenage girls starting their periods and may go on for a few years as hormones settle down. It is also common in women as they approach the menopause.

Often no cause is found and doctors put it down to a condition called 'dysfunctional uterine bleeding'. This means no abnormality has been found to account for it and there is nothing to worry about. If bleeding is heavy, or the erratic cycle is a problem, there are treatments which can help, so contact your doctor.

Bleeding between periods

There are many causes for bleeding between periods. It is common in the first 2-3 months after starting the combined oral contraceptive (COC) pill.