HealthInfo Aoraki South Canterbury
Irregular periods
Mate marama whakahipahipa
Irregular periods means that the length of time between your periods keeps changing. A period is counted from the start of your last period (the first day you saw blood) to the start of your next one.
A normal menstrual cycle may have bleeding for 3 to 8 days and happen every 25 to 35 days. Most of the blood loss happens in the first 3 days.
Your monthly cycle is affected by the levels of the hormones estrogen and progesterone in your body. That is why it is common to have irregular periods during puberty and just before menopause.
Causes of irregular periods
Changes in your cycle are usually caused by a hormone imbalance that causes your periods to stop or become irregular. These include:
- puberty – periods are often irregular for the first year or 2
- being pregnant – periods usually stop. You should take a pregnancy test to rule this out
- menopause – periods often become irregular when menopause starts
- losing too much weight or doing too much physical activity
- stress
- breastfeeding, which may cause periods to stop
- using an oral contraceptive or a intrauterine device. This can cause no periods or very light periods
- a medical condition, such as polycystic ovary syndrome (PCOS).
Important
If you have bleeding after menopause or after sex, this might indicate a serious problem. It is important to see your general practice team straight away rather than waiting to see if the bleeding happens again.
Diagnosing irregular periods
It can be helpful to complete a period (menstrual) diary, which is a record of your periods. You can also download a period tracker app.
Make an appointment with your general practice team if you are worried about any aspect of your periods or if:
- your periods suddenly become irregular
- you could be pregnant
- you have lost weight or you or someone close to you is concerned about your weight
- you wish to get pregnant.
Bring your diary along to your appointment to discuss with your general practice team.
At your appointment, you can expect them to ask you about:
- your periods, such as when they started, how often they occur and how long they last
- your weight, levels of physical activity, lifestyle, general health and any medications you are on
- whether you could be pregnant
- your family history.
Your doctor may check your height and weight and give you a pelvic examination.
You may also need to have some blood tests to check your hormone and thyroid levels. In some cases, you may need an ultrasound. You may have to pay for the ultrasound or use your health insurance, but you should talk to your doctor about this.
Treating irregular periods
You might not need any treatment for irregular periods. You may need treatment if you are trying to get pregnant. Or if you have a condition causing your irregular periods such as polycystic ovary syndrome (PCOS). Your doctor may suggest that you see a specialist doctor in hormones (endocrinologist) or in women's health (gynaecologist).
You may also wish to pay to see an endocrinologist or gynaecologist privately. You can find a private gynaecologist on Healthpoint.
HealthInfo recommends the following pages
- NHS – Irregular periods
More information about irregular periods, including trying to get pregnant with irregular periods.
- Patient.info – Periods and period problems
More detailed information about periods and problems you can have with them.
Written by HealthInfo clinical advisers. Last reviewed January 2025.
SourcesReview key: HIPER-53354
