Some women find their menstrual cycle isn't always regular. Their periods may be early or late, and may vary in how long they last or how heavy they are each time.
Your normal menstrual cycle can be disturbed if you change your method of contraception, or if you have an imbalance of the reproductive hormones oestrogen and progesterone.
Many factors can cause a hormone imbalance, from polycystic ovary syndrome (PCOS) to extreme weight loss and excessive exercise.
Treating irregular periods
Treatment for irregular periods may not always be necessary. However, you should see your GP if:
You may need a different contraceptive, or further investigations may be needed to find out whether you have an underlying health condition.
The average menstrual cycle:
- On average, a woman's menstrual cycle lasts 28 days, but cycles can vary from 24 to 35 days.
- After puberty, most women develop a regular menstrual cycle, with around the same length of time between periods.
- Menstrual bleeding usually lasts two to seven days, with the average being five days.