Periods can stop for all sorts of reasons. Most of the time there is no worrying cause. As long as you are sure you are not pregnant and you feel well in yourself there is no need for concern. If you don't have a period for 3-6 months, or have other symptoms then you should see a doctor. Sometimes periods in teenage girls start later than in others. If your periods haven't started by the time you are 16 (or 14 if you have not started developing in other ways such as getting pubic hair and breasts) then see your doctor.
Periods can also be infrequent, erratic or irregular. If you bleed between your periods or after sex, or after the menopause, then you should discuss this with your doctor.
What is normal?
Monthly bleeds (periods) normally start in girls aged around 12 and finish around the age of 50 when a woman starts her menopause. Periods can start from any age between 9 and 15. The last period in a woman is usually between the age of 45 and 55.
At first periods may not be very regular; however, once they have settled down most women bleed for a few days once a month. For most women, there are around 28 days between the first day of one period and the first day of the next. A gap between periods from 24 to 35 days is normal. Once one period has finished, it is normal not to have any bleeding at all until the next one. See separate leaflet called Periods and Some Period Problems for more details.
When is it normal not to have periods?
There are certain times when it is normal not to have periods. These include:
- Before puberty. Girls start to develop from around the age of 9 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 breast-feeding. If you are fully breast-feeding, 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 breast-feed much less.
- 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. See separate leaflet called Menopause and Hormone Replacement Therapy (HRT) for more details.
- If you are using certain types of contraception. Some types of contraception 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 progestogen-only contraceptive pill (POCP, or mini pill).
- A certain type of coil, called the intrauterine system (IUS).
- A progestogen contraceptive injection.
What are the causes of absent periods?
The medical word for absent periods is "amenorrhoea". If you have never had a period, this is called primary amenorrhoea. If you were having regular periods which have stopped, this is called secondary amenorrhoea. There are many possible causes for both primary and secondary amenorrhoea. Most causes can account for either type.
Often there is nothing to worry about when periods stop, and no serious cause.
Normal reasons for periods stopping are listed in the section above. Some causes of absent periods are discussed below.
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 separate leaflet called Polycystic Ovary Syndrome for more details.
A number of conditions which affect hormone levels may cause periods to stop. 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.
- 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.
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 inherited (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.
The average time for women's periods to stop 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. 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 which is sometimes done for heavy periods, called endometrial ablation, 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.
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 pill (COCP) 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 periods?
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).
- You have lost weight or have symptoms of anorexia nervosa. (See separate leaflet called Anorexia Nervosa for more details.)
- You feel unwell in yourself in any other way.
What should I do if I have had periods which have now stopped?
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 see 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 nine months but your periods have always been infrequent.
- You could be pregnant.
- You wish to become pregnant.
- You have hot flushes 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 breast-feeding.
- You feel unwell in yourself (eg, 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?
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 symptoms 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 hormone levels (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.
Are there any complications of absent periods?
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.
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 a treatment to help with this, so discuss it with your doctor if you want to become pregnant. See the separate leaflet called Infertility - a Summary of Treatments 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.
It is suspected that low oestrogen levels also put a woman at risk of heart disease. Also women with PCOS are at more risk of developing high blood pressure, high cholesterol levels, and diabetes. This combination of risks makes heart disease more of a risk. A healthy diet is particularly important for women with PCOS to reduce the risk.
Other patterns of periods which are different to normal may also occur, as follows.
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.
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 see your doctor. See separate leaflet called Heavy Periods (Menorrhagia) for more details.
Bleeding between periods
There are many causes for bleeding between periods. It is common in the first 2-3 months after starting the COCP. In all other circumstances see your doctor if you have bleeding between your periods or bleeding after sex. You will need an examination and possibly some tests to find out the cause. See separate leaflet called Vaginal Discharge and Vaginal Bleeding for more details.
Dr Mary Harding
Dr Mary Harding
Dr Hayley Willacy