Menstruation is different for every woman. This information will help you understand the menstrual cycle.
What is menstruation?
Menstruation is bleeding from the vagina that happens about once a month, as a normal part of the menstrual cycle. It is also known as having a period.
During this cycle, the hormones make the lining of the uterus become thicker, getting ready in case of pregnancy. Hormones also cause an egg to be released from an ovary, which is known as ovulation.
If a woman doesn’t become pregnant, then her periods starts about 2 weeks after ovulation. The lining of the uterus falls away and, along with some blood, flows out through the vagina. Periods can be light or heavy, and the blood can range from bright red to dark brown. There might also be small clots.
Some women get symptoms leading up to and during menstruation, such as:
- cramps or pains low in the abdomen (tummy)
- bloating or swelling in the abdomen
- constipation before the period
- diarrhoea when the period starts
- mood changes
When do periods typically start?
Girls have their first period during puberty. Most often that is around the age 12 or 13 years old, but girls can start menstruating as young as 9, or as late as 16.
What problems can women have with their periods?
Problems with periods can include:
- heavy bleeding
- period pain (also called dysmenorrhoea)
- unpredictable or irregular periods
- premenstrual syndrome, or PMS, which makes some women feel irritable and sad and can cause bloating, tender breasts and aching
When might periods stop?
Periods stop during pregnancy, and often during breastfeeding.
Some women find their periods stop for a time because of long-term illness, low body weight, stress, lots of strenuous exercise and hormone problems.
Some medications, such as contraceptives, might stop periods. This can be helpful for some women, especially if their periods are heavy or painful.
Sometimes after stopping the pill or other contraceptive, it can take a while for periods to come back.
Periods stop altogether when women reach menopause – the average age is 51-52.
When should I see a doctor?
You should talk to your doctor if:
- you are 16 years or older and haven't started to have periods
- your periods are getting heavier
- your periods last for more than 8 days
- your periods are less than 3 weeks apart
- the pattern of your periods changes
- your periods have stopped and you’re not sure why
- you are bleeding in between periods or after sex
- you are bleeding after menopause
- you have severe period pain
You can also talk to your doctor if, for any reason, your periods are affecting your wellbeing or enjoyment of life.
Learn more about the menstrual cycle on the Jean Hailes for Women’s Health website.
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Last reviewed: June 2020