What is a period?
A period is when you bleed from your vagina every month. Periods are a natural part of your body’s menstrual cycle. During your menstrual cycle, female hormones cause your uterus lining to shed and flow out of your vagina. Your period contains blood, mucus and some cells from the lining of your uterus.
Your first period
Your first period is called ‘menarche’. In Western countries, the average age to have your first period is 12 to 13, but it can start as early as nine and as late as 16. See your doctor if your periods have not started by the age of 16 to 17.
Your last period
Your last period is called ‘menopause’. In Australia, the average age for women to reach menopause is 51 to 52. Some women might reach menopause as late as 60.
Why do you have a menstrual cycle?
Your menstrual cycle prepares your body for pregnancy. If you are not pregnant, your hormones send a signal to your uterus to shed its lining – this becomes your period. Once you start your period, your cycle starts again.
How long is a normal menstrual cycle?
A menstrual cycle is measured from the first day of your period to the first day of your next period. Every woman’s cycle is different. Cycles can also vary at different life stages. For example, teenagers might have cycles that last 45 days, whereas women in their 20s to 30s might have cycles that last 21 to 38 days.
What to expect during your period
Your period might last from four to eight days. Most women lose less than 80 mL of blood in total. Bleeding can vary from a small amount to a heavy loss. Your period flow may be heavier for the first three days and lighter towards the end.
The colour of your period can change from dark brown to bright red.
Some small blood clots are normal. If clots become frequent or larger than a 50-cent coin, talk to your doctor.
Periods can have a distinct smell. If you are worried about the smell, talk to your doctor.
Premenstrual syndrome (PMS)
Some women have symptoms such as irritability, bloating, pimples and tiredness one to two weeks before their period. This is commonly known as PMS. These symptoms can be annoying, but they don’t usually stop women from doing daily activities.
About two-thirds of women experience some breast pain during their cycle and most have one or two premenstrual symptoms. Symptoms usually stop after your period starts. Symptoms can be worse in teenage years and in the lead-up to menopause, possibly due to changes in hormone levels.
Premenstrual dysphoric disorder (PMDD) is a more serious form of PMS, which involves severe symptoms that stop you from doing things you normally do.
Heavy menstrual bleeding
Around one in four women have heavy menstrual bleeding (or heavy periods). A heavy period is when you lose lots of blood each period. The amount of bleeding can change at different life stages, for example, in teenage years or before menopause. Heavy periods are common in women aged 30 to 50.
Period pain is when your uterus muscles tighten. Pain might include cramping and heaviness in the pelvic area, and pain in the lower back, stomach or legs.
Period pain is normal if:
it happens on the first two days of your period
it goes away when you take pain-relief medicines
it doesn’t affect your daily life.
When to see your doctor
You should see your doctor if you are worried about your period. For example, if your period patterns change or your symptoms are so painful they stop you from doing things you normally do.
For more information, resources and references, visit the
Jean Hailes periods web page.
Updated May 2023
Disclaimer: This information does not replace medical advice. If you are worried about your health, talk to your doctor or healthcare team.
We write health information for people with diverse backgrounds, experiences and identities. We use the term 'women', but we acknowledge that this term is not inclusive of all people who may use our content.
© Jean Hailes for Women’s Health 2023
Jean Hailes for Women’s Health gratefully acknowledges the support of the Australian Government.