Your cycle through life

Your cycle is not a fixed setting. It changes with your life stage, just like your skin or your sleep. Knowing what is typical at each stage can help you tell "this is just my age" from "this is worth a check".

Teens: finding a rhythm

The NHS says periods usually begin around 12 and most people have regular periods by 16 to 18. ACOG says cycles of 21 to 45 days are normal for teens and it can take several years to settle. Heavy or very painful periods are still not something to put up with.

20s and 30s: your own pattern

In a study of over 600,000 cycles, average cycle length got slightly shorter with age (about 3 days shorter between the youngest and oldest groups), and the spread between one person's own cycles also got smaller as age rose through the late 20s and 30s. Hormonal contraception, pregnancy, breastfeeding, stress and medical conditions can all rearrange things in this stage of life.

Perimenopause: the shake-up

The NHS says menopause and perimenopause usually affect people between 45 and 55, and the UK average age of menopause is 51. Periods usually do not just stop suddenly. They tend to get less frequent over months or years. Some people notice shorter cycles or heavier bleeding first, then longer gaps.

• Menopause is a point in time: 12 months with no periods (NICE uses this if you are 45 or over and not on hormonal contraception).
• Perimenopause is the run-up, when hormone levels fluctuate.
• After menopause, any vaginal bleeding needs checking by a GP.