The Menstrual Cycle and Period Problems

A period, or menstruation, marks the beginning of the process by which the uterus, or womb, prepares itself for pregnancy. Sarah has a look at the process and what can go wrong...
04 January 2006


A period, or menstruation, marks the beginning of the process by which the uterus, or womb, prepares itself for pregnancy. Each month the lining of the uterus, called the endometrium, is shed from the body, producing a period, and a new lining is grown to replace it.

Whilst it's convenient to think of the menstrual cycle as a monthly event, indeed we get the word menstruation from the 28 day cycle of the moon, only about 12% of women actually have a period every 28 days. Most women with regular periods have a cycle lasting 21 to 35 days, with 'day 1' traditionally used to denote the first day on which bleeding begins.

Menstrual_cycle_hormones_graphThe process of menstruation is controlled by 4 key hormones including oestrogen and progesterone, which come from the ovaries, and FSH and LH, which are released by the pituitary gland in the brain.

At the beginning of each monthly cycle the levels of FSH (which stands for follicle stimulating hormone) begin to rise, triggering egg-containing follicles in the ovaries to grow and produce oestrogen. As the oestrogen levels climb, the lining of the uterus responds by thickening, developing a rich blood supply and preparing itself to receive a fertilised egg, or embryo. Other oestrogen-sensitive tissues in the body respond too; the vagina secretes sugars which are converted by local 'healthy' bacteria into lactic acid, helping to reduce the risk of infection, and the mucus from the cervix becomes thinner and more copious, which helps sperm to pass into the uterus more easily.

When oestrogen levels peak, usually around day 14, the pituitary releases a surge of FSH and LH (luteinising hormone) which together trigger ovulation, the process by which an egg is released from one of the follicles in the ovary. After the egg is released, the ovary starts producing the other key hormone, progesterone, which helps to prepare the endometrium to receive and nourish a growing embryo.

If a baby does begin to grow, the placenta, which forms the lifeline connecting the developing baby to the mother, takes over the production of oestrogen and progesterone from the ovary. Together these two hormones help to keep the endometrium in good condition until the baby is born.

But if no embryo implants in the uterus, after day 21 the ovary stops producing oestrogen and progesterone. Without their nourishing effects the endometrium begins to break down, resetting the cycle, and triggering a period by day 28.


Although it closely resembles blood, menstrual fluid actually comprises a mixture of tissues and secretions from inside the uterus including water and mucus from the uterine glands, blood from capillaries feeding the endometrium, and the glandular tissue of the endometrium itself. Most women menstruate for 2 to 7 days, lose between 20 and 80 millilitres of blood, and report the heaviest bleeding at the beginning. Once the period is over, the endometrium begins to replenish itself from a layer of stem cells in the wall of the uterus.


This is the term used to describe the time when a woman starts her periods. For most girls this occurs around 12 years of age, although it is very variable and ranges from 8 to 16 years.

The age at which periods begin is affected by both genetic and environmental factors. Early or late menarche can run in families, although girls are now starting their periods at a younger age than they did 100 years ago, probably because they are healthier and better nourished.


Problems related to periods are a common reason for a woman to see a doctor. A 1990 survey conducted by MORI (Market Opinion and Research), involving women of reproductive age, found that one in four (25%) of those questioned reported a recent painful period, one in five (20%) reported a recent heavy period, and one woman in every two (50%) said she had experienced both a recent heavy and painful period.

Period problems are also becoming more common. This probably reflects the fact that family sizes have shrunk over the last 50 years to an average of fewer than two children per couple. Since menstruation ceases temporarily during pregnancy, and whilst a mother breast feeds, fewer pregnancies mean more periods in total and hence a greater likelihood of a woman experiencing problems.


Dysmenorrhoea is the medical term for painful periods. Most women experience period pains at some time, but the severity of the symptoms varies from woman to woman and ranges from mild discomfort to excruciating pain together with nausea and vomiting.

What causes period pains?

The uterus is a muscular organ shaped like an upside-down pear. During labour the uterine muscles (called the myometrium) produce the contractions which push a baby out. The uterus also produces small contractions during a period, which help to cut off the blood supply to the endometrium (the lining of the womb), to reduce blood loss, and to push the menstrual fluid into the vagina. It is these small contractions which cause period pain. They are triggered by chemicals called prostaglandins, the action of which can be blocked by simple pain killing drugs like aspirin and mefenamic acid.

Period pains usually improve with age, and it has been suggested that exercise can help by releasing endorphins, the body's natural pain-killers. Worsening period pains and uncomfortable menstruation can sometimes be a sign of depression and anxiety. If you think that this might be the case you should see your doctor because when depression is treated, any associated menstrual symptoms usually resolve themselves.


Throughout their fertile life, for reasons we don't understand, some women never establish a regular menstrual cycle. This can be socially inconvenient, because irregular periods can make it more difficult to plan holidays or other activities, and since ovulation is more difficult to predict it can sometimes cause problems related to becoming pregnant.

Irregular periods are also common during the first 2 or 3 years after the menarche (the onset of menstruation), for a few months after giving birth or following a miscarriage or termination, and during the peri-menopause or climacteric, the time just before your periods finally stop, called the menopause (see above).

Causes of irregular periods

  • Stress
  • Contraceptive started recently or a recent change in contraceptive
  • Pregnancy/miscarriage/ectopic pregnancy (where the baby grows in the fallopian tube or elsewhere outside the uterus - usually causes pain and bleeding in early pregnancy)
  • Polycystic Ovarian Syndrome - small harmless ovarian cysts, causes one or more of the following symptoms - irregular periods, hairiness, acne, weight gain or infertility.
  • Dietary change with sudden gain or loss of weight
  • Hormonal imbalances.

If your periods are irregular, make sure you eat well and exercise regularly. Stress from a variety of sources including exams, work, relationship problems and worrying that you might be pregnant, can also affect the timing of your period. But if you are sexually active, and there is a chance that you could be pregnant, always do a pregnancy test and see your doctor. Sometimes bleeding between periods (often noticed as spotting) can be mistaken for irregular periods, but might be a sign of a more serious underlying disorder such as cervical cancer. Always ensure that your cervical pap smears are up to date, and if you have any doubts, see your doctor for a check up.


Amenorrhoea falls into two categories. Primary amenorrhoea occurs when a girl does not start her periods at all. More common is secondary amenorrhoea, where your periods have started but then abruptly stop for more than 6 months. There are a number of reasons why menstruation should fail to start, or stop suddenly.

  • Pregnancy
  • Delayed puberty - this can run in families.
  • Intact hymen - the hymen is a membrane in the vagina which is torn when your lose your virginity. The periods may have started but the blood cannot escape if the hymen is intact. This is easily rectified by a gynaecologist who can make a hole in the hymen.
  • Weighing too little - in order to menstruate, fat must make up at least 15% of your body weight. Excessive exercise, malnutrition, and eating disorders such as anorexia or bulimia, can reduce total body fat below this critical level and cause menstruation to stop. This also increases your risk of developing the bone-thinning disease osteoporosis. However, once the fat is replaced, normal menstruation resumes.
  • Hormonal problems - as a result of stress, excessive body weight, or an abnormality with the signaling between the hypothalamus and pituitary gland in the brain and the ovaries.
  • Polycystic ovarian syndrome - this causes small harmless cysts on the ovaries and can result in irregular or no periods, hairiness and acne, weight gain and sometimes infertility.
  • Ovarian or pituitary tumours (although these are rare)
  • Premature menopause due to ovarian failure.

Your doctor will advise you on the correct treatment once the cause of your amenorrhoea has been identified.


Menorrhagia (heavy periods) is the commonest reason for a woman to be referred to a gynaecologist by a GP. On average, women lose 20 to 80 mls blood with each period. Different people perceive their period volume in different ways - what is heavy bleeding for one woman may be judged as light by another. But more than 80mls is considered excessive. One way to gauge the heaviness of a period is to count the number of tampons or sanitary towels used per day. Clearly a woman who is experiencing flooding of blood onto the floor, or someone who is having to use both a tampon and a towel, and change them hourly, is having a heavy period. Using more than 10 tampons or sanitary towels per day usually indicates a heavy period. Such excessive bleeding can lead to anaemia and the symptoms of looking pale, feeling tired and weak, and shortness of breath.

Causes of Heavy Periods

  • Dysfunctional uterine bleeding - this is the term used to describe heavy periods which generally occur shortly after starting your periods or close to the menopause. These heavy periods usually occur during a cycle when you do not ovulate.
  • Miscarriage/ectopic pregnancy - always do a pregnancy test if you have heavy bleeding out of the blue. ALWAYS SEE A DOCTOR IF YOU HAVE BLEEDING AND/OR PAIN IN PREGNANCY.
  • Hypothyroidism - this is an underactive thyroid gland and one of the symptoms of this is heavier periods.

    Copper Coil - can cause heavier periods in some women.

  • Fibroids - these are benign (harmless) growths coming from the muscle wall of the uterus that range from the size of a pea to the size of a melon. Because fibroids increase the surface area of the womb they also increase the amount of blood lost during a period. They are also more common in Afro-Caribbean women. Large fibroids occasionally press on the bladder or bowel, causing frequent urination or constipation. Your doctor may be able to feel a fibroid when they examine your abdomen, or they can organise an ultrasound scan of you pelvis to check for them.
  • Endometriosis - this occurs when pieces of the lining of the womb grow where they shouldn't - outside the womb on the ovary, fallopian tube, outside of the bowel, or inside the wall of the pelvis. During menstruation these spots of endometriosis bleed too but, because the blood can't get out of the pelvis, and it can cause pain. Women with this condition can have problems with heavy periods and commonly complain of pain for up to a week prior to their period and then during their period also. You will need to see a gynaecologist if your doctor suspects this as endometriosis can only be seen during a laparoscopy (a keyhole operation where a camera is passed into the abdomen through your umbilicus or belly button. This camera can look down onto the uterus, tubes and ovaries as well as around the pelvis walls and outside of the bowels to look for the red-brown spots of Endometriosis). Once a diagnosis has been made, your gynaecologist will then advise you on medicines to help, or may be able to cauterise (burn) the spots to get rid of them.

  • Pelvic infections - these can sometimes cause heavy periods. Your doctor can take swabs from the vagina to check for a number of infections including gonorrhoea, trichomonas vaginalis, bacterial vaginosis (BV for short), thrush, and chlamydia. Chlamydia can also be diagnosed with a new type of urine test. It is important to pick up these infections as Gonorrhoea and Chlamydia can both cause infertility by scarring and narrowing the fallopian tubes. They are easily treated with antibiotics. It is important to use a condom during sex to avoid these infections and have regular check-ups particularly if you have had unprotected sex, or you have changed your partner.
  • Polyps - these are small mushroom-shaped outgrowths from the lining of the uterus. Like fibroids they cause an increase in the surface area of the womb and heavier periods. These may be seen on an ultrasound if they are large, but more commonly a hysteroscopy is needed to see these.
  • Blood disorders - sometimes problems with the ability of the blood to clot can trigger heavy periods - your doctor will be able to do a simple blood test to check. You may be sent to a haematologist (a blood disease specialist) if you doctor finds any abnormalities on the simple blood tests.


If you are having problems with your periods, or if your periods have changed in any way by becoming heavier, more painful, irregular for more than 4-6 months, you have noticed spotting between periods (called inter-menstrual bleeding), bleeding after sex, or bleeding whilst pregnant, you should see your doctor.

It is helpful for your doctor or gynaecologist if you can keep a "menstrual diary", or a record of your period dates, length of periods, and how heavy they are, as well as the times and dates of any spotting or bleeding after sex. This will help them to decide on the tests needed.

Tests your GP or gynaecologist may do:

  • Blood tests - blood count, thyroid function, blood clotting.
  • Pap smear test - to take a sample of cells from your cervix to look for abnormalities or signs of cervical cancer.
  • Swabs for infections.
  • Ultrasound scan - to look for fibroids, polyps, ovarian cysts etc.
  • Pipelle (a womb lining biopsy - where a small plastic tube is passed into the uterus to obtain a small sample of the endometrium)
  • Hysteroscopy - a test done under general anaesthetic or Sedation/Local anaesthetic by your gynaecologist. A camera is passed into the womb through the vagina and cervix to look at the lining of the womb.
  • Laparoscopy - an keyhole operation done under general anaesthetic to look inside your abdomen with a camera to view the uterus, tubes, ovaries, pelvis wall and bowel.
  • Laparotomy - a bikini line operation, to view the inside of the pelvis, uterus, tubes and ovaries. This is usually only done if a keyhole operation is not possible. Your gynaecologist will explain to you why this surgery may be needed.


Your GP or gynaecologist can discuss which options are best for your case.

  • Pain killers - Panadol, Ibuprofen, Aspirin, Mefenamic acid.
  • Medicines to reduce the amount of blood loss - eg. Tranexamic acid, Mefenamic acid, or Norethisterone.
  • Oral contraceptive pills - better for younger women with irregular, painful or heavy periods. These can regulate your cycle, reduce pain, and make your bleed lighter. Care should be exercised if you are aged over 35, a smoker, or you have a family history of breast cancer, DVT (deep vein thrombosis) or a PE (pulmonary embolism), or stroke in a family member at a young age.
  • Antibiotics for sexually transmitted infections.
  • If you have a copper coil (intra-uterine device) this can cause heavier and more painful periods. You could have the coil removed, and discuss alternative contraception with your doctor.
  • Mirena coil (intra-uterine system) - this coil contains a progesterone-like hormone which thins the lining of the womb and makes your period lighter. It can cause slightly irregular bleeding for the first 3-6 months, but is an excellent treatment for heavy periods particularly if your have completed your family, or are near the menopause. It is also one of the most reliable contraceptives available.
  • D&C - "dilatation and curettage" / polypectomy - the cervix is dilated in an operation under general anaesthetic, and the uterus lining is scraped using a special instrument called a curette to remove polyps or small fibroids. Another operation called a myomectomy is sometimes done to remove fibroids. This is an abdominal operation done via a bikini line incision under general anaesthetic.
  • Hysterectomy - the uterus can be removed via the vagina (if there are no large fibroids or polyps, and no ovarian problems such as cysts), or abdominally with a bikini line incision if you have large fibroids or enlarged ovaries.
  • Colposcopy - If there is a problem with abnormal cells or cervical cancer on your Pap smear, you will be sent to your local colposcopy clinic. At this clinic the cervix is visualized using a special microscope called a colposcope, and any abnormal cells can be treated or removed under local anaesthetic.


This is also known as PMT (pre-menstrual tension). Most women are aware of some of the symptoms of PMS around the time of their period. Common complaints include breast tenderness, headache, backache, abdominal bloating or food cravings (often carbohydrates or chocolate!). For many women these are not particularly problematic, but in others they can be severe. Other PMS symptoms include acne, anxiety, fatigue, insomnia, faints, altered sex drive, swelling of fingers or feet and ankles, depression and mood swings. In the worst cases these mood swings can lead to anger, aggressive behaviour or suicidal thoughts.

The symptoms of PMS can also be very variable from one month to the next. Underlying depression and stress can often make the symptoms of PMS much worse.

Self-help measures to reduce PMS problems

  • Good diet
  • Plenty of water
  • Reduce smoking and alcohol intake
  • Exercise
  • Self-relaxation techniques / reduce stress
  • Self-help groups
  • Sage and fennel are thought to reduce irritability
  • Evening Primrose oil (Gamolenic acid)

If the above things fail to help, talk to your GP about referral to a gynaecologist.


This is the time when periods stop. The average age at which this occurs is 50, but ranges from 45 to 55 years. Around 20% of women seek medical help around this time for symptoms related to the menopause including irregular cycles, heavy periods, hot flushes, palpitations, vaginal dryness, irritability, depression, memory difficulties and problems caused by thin bones (osteoporosis).

Simple measures including lubricants like KY jelly, or even vaginal oestrogen creams, can help with problems related to dryness. A Mirena coil can help to lighten heavy bleeding and is also a reliable contraceptive. This coil contains a progesterone-like hormone which thins the endometrium so periods become lighter and may even stop. It can often be used in place of more drastic measures such as a hysterectomy.

HRT (hormone replacement therapy) in recent studies has been shown to increase the risk of breast cancer and may not be as protective against cardiovascular disease such as heart attacks and strokes as it was first thought. But HRT is very effective at reducing menopausal symptoms, particularly if a woman is struggling with severe symptoms affecting her lifestyle and relationships. However, HRT should not be used in women who have had breast cancer, and care should be taken in women with high blood pressure or a history of deep vein thrombosis (DVT), pulmonary embolism, or stroke. Your doctor will be able to guide you towards the right decision for you.

It is also important to see your doctor if you have any post-menopausal bleeding as this is not normal and needs further investigation.


Great article Sarah,

I’m so glad you’re raising awareness to the link between hormones and acne. Hormonal factors are particularly linked to acne around the mouth for women. Sometimes the acne is connected to conditions like Polycystic Ovary Syndrome (as you mention in the article) and Congenital Adrenal Hyperplasia.

Thanks again for the great info,


I'm 23 with two little boys. One born in 2015 by C-section, and the other in 2017 by C-section also. Then probably 2 weeks following the last C-section I had my tubes removed because I had severe preeclampsia both pregnancies. My period came the first month or two but I got suddenly ill before they came like I had a stomach bug or a bad flu. Sudden nausea, vomiting, diarrhea, body aches, chills, very irritable, anxiety, etc. Now I haven't had an actual period for two months. Just spotting. At times I'll only notice it when I wipe, or some spot on a pad. I still feel a little unwell the day it comes. Any thoughts on what my problem could be?

My period was not proper for last two months.i consulted gyno and had Julian a tablet but after consuming dat I m not getting my period I feel uncomfortable in my upper worried .

I've had unsettled periods all my life and heavy all my life and they have gotten heavyer as I've got older in the past it was due to anirexia and Belima I've been recovered now for 13 years evern tho I never knew when I was going to have them I've always had intence pain week before due in and after but not as bad as I've just turned 30 and my periods are like a severed vain I'm dizzy fainting so much pain it's worse than laber and I was in laber for 2 weeks so it's really painful and I'm bedridden I. Wearing the thickest pads on market 4 of them and I'm going through in half a hour with a swimming pool on top I've never been so much pain and it's not pregnancy because my husband had op so we can't have more children due to my nearly death dieing laber what's wrong with me why only now it's so bad

My monthly flows , flowed only for 2days instead of 4days. But still on my normal cycle. What is the cause of that flow for only 2days? Is it normal?

I did my ultrasound for cyst. Now my report is normal.. but period i am not getting bleedind properly.. just dry.. not even there is need to take pad.. wat will be my problem

This may be you age. How old are you?

I always have heavy flow on day 4 of my menstruation, and I've been menstruating for over 2 decades now. Should I be worried ?

My periods are never regular, but this time I can't tell what's going periods. Just mucus-ish mixed with blood that can't stain my pads maybe till I wipe.

What would be the problem?

I was pregnant for three month and the baby die in my stomach so the doctor took the baby off and clean my the womb (EOU). And since then I have not exprience my mense for four mouth. Do I have any problem in my womb.

Having sharp pain on my tummy and on my fallopian cube even whenn I'm breathing I can feel it all the even I'm eating

Have you done a pregnancy test? When was your last period? It would be best to make an appointment with your doctor asap to have your tummy checked. Take a urine sample with you and they can do a pregnancy test if you haven't done one yet and dipstick the urine to check for infection.
If your pregnancy test is positive it would be best to see a doctor straight away to check this is not an ectopic pregnancy.
Best wishes.

After birth of my first baby my mensus were regular for about 7-8 months but after that the periods are very painful and with little bleeding...plz suggest what can i do .....

I would see your GP to discuss your periods. They can advise you on painkillers to help, and arrange an ultrasound of the pelvis if necessary to investigate the cause for the pain. Best wishes and hope everything settles down.

Respected madam/sir
I have a thyroid problem and I am exposed to irregular menstrual cycles....from the last two months I was not having periods...and the 3rd month I experienced a little bit of mucous blood(which indicates my menstrual cycle has begun)but,the bleeding is not occurring...I experience a drop of mucous blood daily but the heavy bleeding is not occurring...what might be the reason?

Your thyroid problem may be causing the problem, but it is important that you do a pregnancy test, and see your doctor. They will be able to arrange relevant blood tests/ultrasound scan/smear test to investigate this further to make sure there is no underlying more serious cause. Best wishes.

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