The menstrual cycle and the impact of menstrual disorders

The normal menstrual cycle length does not vary by more than 7 to 9 days between cycles, within a range of 24 to 38 days¹; bleeding lasts up to 8 days and is less than 80 mL.

The cycle is divided into follicular and luteal phases. The follicular phase extends from the first day of menstruation until ovulation; this can vary in length. The endometrium proliferates during this time under the influence of estrogen. The luteal phase has a duration of around 14 days following ovulation. During this phase, the corpus luteum secretes progesterone, inducing secretory change in the endometrium. Anovulation causes excessive endometrial proliferation, which contributes to heavy bleeding when the next menstruation occurs. To manage anovulatory cycles resulting in amenorrhoea (absent bleeding for more than 3 months following previously regular cycles, or more than 6 months following previously irregular cycles) or oligomenorrhoea (fewer than 9 cycles per year), see advice on secondary amenorrhoea.

Menstrual disorders are common during the reproductive years and can have a disabling impact on study, work and social life. They include heavy menstrual bleeding in up to 30% of individuals, dysmenorrhoea in 50 to 90% of individuals and mood disorders in up to 40% of individuals.