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.

However, you shouldsee your GPif:

  • you have bleeding or spotting between periods or after sex
  • you have very heavy periods ,where you need to change your tampon or pad every hour or two, or you have to wear both a pad and a tampon
  • you experience heavy bleeding that floods into your bed or through your clothes
  • your periods last longer than seven days
  • your periods are more frequent than once a month

You may need a different contraceptive, or further investigations may be needed to find out whether you have an underlying health condition.

After puberty, most women develop a regular menstrual cycle, with around the samelength of time between periods.

Menstrual bleeding usually lasts two to seven days, with the average beingfive days.

Periods and period problems

  • heavy periods
  • absent periods
  • painful periods
  • Content supplied by the NHS Website

    Medically Reviewed by a doctor on 2 Jun 2016