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Periods - the facts

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Having a period (or menstruating) is a normal and natural part of being a woman. Girls usually have their first period about a year after the first signs of puberty (when they start to get taller and breasts start to grow), but the time this happens can vary a lot.


The menstrual cycle and menstrual periods

Having the first period tells a girl that her body has changed, and she is becoming a woman who will be able to have a baby, if and when she want to. The period (the days that she loses blood through the vagina) is part of a 'cycle' of hormone and body changes.

  • During each cycle, the lining of the inside of the uterus (womb) gets thicker, so that if the egg (ovum), which is released from the ovary each cycle, is fertilised by a sperm, the uterus is ready to provide a place for the baby to grow.
  • A period is when the lining separates from the rest of the uterus because it is not needed for this egg to grow. The old lining is 'lost' and the uterus gets ready to make a new lining for the next egg.
  • The 'loss' is mostly blood, which can be bright red, dark red or dark brown, and sometimes has some clots (dark lumps of blood) in it.
  • How long a period lasts and the time between periods varies for different women.

The menstrual cycle

When do periods start?

The first period happens for many girls between the ages of 12 to 14 years, but quite often it is earlier (from as early as 9 years old) or later (up to 16 years).

  • Girls start having periods at different times depending on how quickly they are developing.
  • If a girl has not had her first period by the time she is 16, this is still probably normal, but it would be worth checking with a doctor.
  • Once she gets her period, it may take quite a long time for her body to settle into a regular pattern – maybe up to a year – but most women eventually do get into a regular cycle.
  • It is a good idea for her to keep track of when her period is due, maybe on a calendar or in her diary.
  • If the pattern changes and she has been sexually active, it may mean she is pregnant. It could also mean there are other reasons - such as losing too much weight or exercising too much.

What happens in the monthly menstrual cycle?

  • On average, a cycle lasts about 28 days, but it’s quite normal to have a shorter or longer cycle. So her cycle will probably be normal for her even if it is 21 days long, or 35 days!
  • ‘Day 1’ of a cycle is the first day of bleeding, the first day of a period. This bleeding is called menstruation.
    • On average, when periods have become regular, this bleeding lasts for about 5 days.
    • For many young women in the first year or so of having periods, the bleeding can last for longer (7 to 10 days is fairly common).
    • Usually bleeding is heaviest on the first or second days.
    • Many young women get quite a lot of crampy pain in their lower tummy just before and during the first day of their period.
  • As soon as one period finishes, the lining of the uterus starts to grow again and becomes thicker ready for another egg (ovum). It continues to get thicker until a couple of days before the next period starts (unless the ovum has been fertilised and the woman is pregnant).
  • About 12-16 days before the next period, an egg is released from the ovary. This is called ovulation. (A few women feel a sharp pain in the side of their tummy at this time.)
  • This egg travels along the fallopian tube from the ovary to the uterus. An egg survives for only about 24 hours if it is not fertilised by a sperm.
  • If fertilisation does not happen, hormone levels drop, and she has a period. And then the whole cycle continues.

How much blood is lost?

  • The loss is mostly blood, but also contains some mucus and other tissues from the lining of the uterus.
  • Sometimes it seems like a lot of blood, but it is usually less than 100ml. If she weighs 50kg she will have about 3.5 litres of blood in her body, so losing 100ml with a period will not cause health problems. The blood that she loses will be quickly replaced by the blood-forming cells in her bone marrow.
  • Sometimes a woman will have very heavy periods, and lose a lot of blood. She may have a lot of clots in the blood that is lost. If too much blood is lost she can become anaemic (not enough red blood cells). She may need to have extra iron in her diet (eg. from foods or iron tablets) to help her blood form cells to replace all that lost blood.

Symptoms before a period

Many women experience some symptoms before a period (called pre-menstrual symptoms) due to all the hormone changes that are happening. They can include:

  • Feeling bloated and heavy.
  • Cramping pains around the lower abdomen, in the legs or sometimes in the lower back.
  • Getting more pimples than usual.
  • Feeling tense, irritable, sensitive, emotional, tired.
  • Breasts becoming a little bigger and tender.
  • Hair becoming more greasy.

Will other people know she has her period?

No way! Despite sometimes feeling like someone can see a pad, or notice that she is ‘different’ at this time of the month, people will not notice that she is having a period. At any one time about 20% of all young adult women will be having a period. Can you pick which other students are having a period? Or which teachers are having their period? Do you know when your mother is having her period, unless she tells you?

Only she will know, unless she tells someone herself.

Painful periods

Many young women, and some older ones, get a lot of pain when their period starts. This pain (called dysmenorrhoea) comes from the muscles in the uterus contracting (tightening). This is sometimes called 'cramps'.

  • If the pain is not too bad, simple things like a hot water bottle on her tummy, some exercise, and perhaps medicine for pain (such as paracetamol or ibuprofen) could help.
  • If she is having a lot of pain, get her to see a doctor, because there are some safe medicines which can make a lot of difference.
  • It will be useful to mark when periods are coming on a calendar, because some of the medicines work best if they are taken just before the period pain starts.
  • Sometimes the doctor will recommend that she starts taking a contraceptive pill (The Pill), but there are other treatments which can help a lot too.
  • Painful periods are a common reason why young women need to take time off school or work, but almost always there is a treatment which can reduce the pain a lot so that she doesn't have to take that time off.
  • Recent research shows that young women who smoke are more at risk of having premenstrual tension and heavy painful periods. The symptoms increased with the number of cigarettes smoked.

Pre-Menstrual Syndrome

For some women, the changes in the week or so before a period comes can be distressing both emotionally and physically. This is sometimes called pre-menstrual tension or pre-menstrual syndrome (PMS). If she notices symptoms every month before her period is due, then it may be due to PMS.

Some of the symptoms that can come with PMS are:

  • migraines
  • irritability, depression or mood swings
  • tiredness or much more energy than usual
  • feeling bloated
  • food cravings (sweet foods usually, such as chocolate!)
  • constipation or diarrhoea
  • difficulty concentrating
  • decreased efficiency
  • back aches
  • sleeplessness
  • tension.

Sometimes some lifestyle changes can make these symptoms less of a problem. She could try a few of these ideas:

  • eating a healthy diet
  • increasing exercise level
  • getting plenty of sleep
  • yoga, massage or meditation
  • swimming or dancing
  • eating foods high in Vitamins B6, B1, B-complex, and C, and in calcium and iron (if her diet does not adequately supply her with these)
  • avoiding smoking.

Some women find that vitamin B6 supplements or some herbal medicines are useful.

If PMS is a problem, get her to see her doctor.

Blood on your clothes

When a girl gets her period and she isn't ready for it, she may get some blood on her clothes. This kind of thing actually happens a lot.

  • She can go to someone and ask for some help. For example if she is at school, a teacher could get a tampon or pad and let her change clothes (remember all female teachers have periods and they know what this is like!)
  • As for the stain, it is nothing that cold water and soap can't fix.
  • Usually periods start slowly so she will get a bit of a warning before there is a lot of blood. Some young women keep tampons or pads at school or work just in case.
  • Remember too that about one in five of her friends will probably have a period at the same time, and the friend may be able to help if she needs a pad.

When periods stop!

For normal periods to occur, many parts of her body need to be working well, including her ovaries, uterus, pituitary gland (part of the brain) and hypothalamus (another part of your brain). There are lots of (rare) ways for something to go wrong, but the three common causes for periods to stop are:

  • getting pregnant (this only happens if she has sex)
  • losing too much weight
  • exercising too much.

If periods stop, then it is important to have a doctor check what is going on.

All about tampons and pads

She can choose herself whether she would like to wear tampons or pads (sanitary napkins). She will probably make this decision based on what feels most comfortable for her.

  • Most young women start with pads, but tampons can be used (she does not need to have been sexually active to use a tampon). Keep both forms of protection wrapped up and clean until used.

Sanitary Napkins

  • Most pads (or sanitary napkins) are made to stick to the inside of pants (knickers) and absorb the blood.
  • They have a plastic lining underneath to prevent any leakage, and crystals inside to absorb the fluid.
  • Change them several times a day. To dispose of them, wrap them up (you could use toilet paper, newspaper or a plastic bag) and place them in the rubbish bin.
  • Do not flush pads down the toilet or there will be big blockage problems ahead.
  • Pads are a common choice when she has just begun menstruating - they are easy to use, and they fit everyone.
  • There are extra large ones for overnight, or when the period is very heavy, and small ones (mini's) for ‘light’ days when the blood loss is getting less.


  • Tampons are placed inside the vagina and also absorb the blood. Tampons will not get lost inside the body.
  • Some women find that using an applicator is easier, but most women don’t use one. Make sure hands are clean before inserting a tampon.
  • Tampons have a string on the end, which you pull on to remove it.
  • Tampons should be replaced about 4 or 5 times a day. Inside a tampon box there is a piece of paper telling step-by-step how to use them.
  • Tampons should be disposed of in the same way as pads - "wrap 'em, don't flush 'em"!
  • It is probably better to use a pad overnight, because leaving a tampon in all the time can dry out the lining of the vagina, and there is a small risk of getting an infection in the vagina. If there is a smelly or itchy rash, pain or tenderness, or feel unwell, stop using tampons and see a doctor.
  • There are several myths that say that there are chemicals inside tampons which can poison a woman or cause other harms. These myths are not true.

Playing sport

  • Women can play any sport while she has a period.
  • Some elite sportswomen report that they can perform even better than usual around the beginning of their period. They seem to have extra energy and maybe a bit more aggression than usual.
  • Playing sport seems to help relieve some premenstrual symptoms too.
  • Shorts will hide her knickers, so that no one will notice she is wearing a pad.

Swimming and having a bath

  • She can swim and have baths while she has her period. The water will quickly wash out any blood in the vagina and after the first few minutes the loss will be so small no-one else will see it.
  • Bathwater, pool water or sea water cannot get inside her body when she has a period (just as it cannot get inside when she is not having a period).
  • Going to the toilet before going swimming could help her feel more confident about this.
  • Women who swim a lot usually use a tampon. They need to remove the tampon as soon as they get out of the water, and put in a dry one.

More to read

Raising Children Network 

Better Health Channel (Victorian Government) 

There is a lot of information on the TeensHealth.org website - search 'periods'. 

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The information on this site should not be used as an alternative to professional care. If you have a particular problem, see a doctor, or ring the Parent Helpline on 1300 364 100 (local call cost from anywhere in South Australia).

This topic may use 'he' and 'she' in turn - please change to suit your child's sex.

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