Summary
Read the full fact sheet- Periods usually happen every month.
- Amenorrhoea is the absence of menstrual periods.
- It's normal to miss periods sometimes.
- Disrupted hormones is the most common cause of absent periods.
On this page
What is a period?
A period is when you bleed from your vagina every month. Periods are part of your body's menstrual cycle.
The menstrual cycle
The menstrual cycle prepares your body for pregnancy. If you're not pregnant, your hormones send a signal to your uterus to shed its lining. This is your period. Once your period starts, the cycle begins again.
A menstrual cycle is measured from the first day of your period (day one of your cycle) to the day before your next period. The average length of a menstrual cycle is 28 days, but every woman’s cycle is different.
Menstrual cycles can change over time. For example, an adolescent's cycle may last for about 45 days, while people in their 20s and 30s may have a cycle that lasts between 21 and 38 days. The average length of a menstrual cycle is 28 days.
Is it normal to miss one or more periods?
It’s normal to miss periods at different times in your life. For example:
- when you first start getting your periods
- while pregnant
- while breastfeeding
- in the lead-up to menopause (your final menstrual period).
Absent periods (amenorrhoea)
When you don't get your period at all it's called 'amenorrhoea'. This can be short-term or long-term. If your period is late or stops, it's important to check if you're pregnant.
Primary amenorrhoea is when menstrual periods haven't started by the age of 16 but you have other signs of puberty such as pubic hair and breasts.
Secondary amenorrhoea is when periods stop for 3 months or more in a row after you've previously had regular periods.
What causes absent periods?
Hormonal imbalance is the most common cause of absent periods. This can be caused by:
- polycystic ovarian syndrome (PCOS)
- pituitary or thyroid disease
- excessive exercise
- low body weight and poor nutrition (i.e. eating disorders such as anorexia nervosa)
- weight gain
- severe anxiety and stress
- travel
- menopause
- Asherman's syndrome (a rare genetic condition where scar tissue forms inside the uterus).
Treatment options
Treating absent periods depends on the cause. If another condition is causing amenorrhoea, your doctor will usually treat that first. Treatments include:
- hormone therapy
- medication
- lifestyle changes
- surgery
- nutritional advice
- specialist care (in the case of an eating disorder).
When to see your doctor
See your doctor if:
- your periods have not started by the age of 16 to 17
- you have missed 3 or more periods in a row
- you have had fewer than 9 periods in a year
- you have noticed changes in the pattern of your periods.
It's a good idea to record information about your periods to discuss with your doctor. For example, when you get your period, the length and heaviness of your period and how your periods impact your life.
More information
For more detailed information, related resources, articles and podcasts, visit Jean Hailes for Women’s Health.
Where to get help
- Klein D, Paradise, SL, Reeder, R 2019, ‘Amenorrhea: A systematic approach to diagnosis and management’, Am Fam Physician, vol. 100, no.1, pp. 39-48.
- Reed BG, Carr BR. The Normal Menstrual Cycle and the Control of Ovulation. [Updated 2018 Aug 5]. In: Feingold KR, Anawalt B, Blackman MR, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000
- Tejpal C, Poudel I, Jahan N. Is Metformin the Answer for Distressed Females with Menstrual Irregularities?. Cureus. 2019;11(8):e5460. Published 2019 Aug 22. doi:10.7759/cureus.5460
- Healthy periods, Royal Women’s Hospital
- Asherman Syndrome, The Royal Australian and New Zealand College of Obstetricians and Gynaecologists
- Amenorrhoea, Queensland Health
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