Classification of amenorrhoea
Primary amenorrhoea is defined as the absence of menarche (onset of menstruation) in individuals presumed female at birth by:
- age 13 years in a female without breast development (see Delayed puberty in females)
- age 15 years in a female with normal growth and breast development
- 5 years after breast development that occurred before age 10 years.
Secondary amenorrhoea is defined as the absence of menstruation for:
- more than 3 months in females with previously regular menstrual cycles
- more than 6 months in females with previously irregular menstrual cycles.
Menstrual cycles are often irregular for the first 2 years after menarche. After this stage, oligomenorrhoea (fewer than 9 cycles in 1 year) requires assessment.
Primary and secondary amenorrhoea commonly result from a lack of ovarian hormonal function (female hypogonadism) and may be accompanied by infertility. For advice on infertility aspects of female hypogonadism, see Anovulatory Infertility. Female hypogonadism may be:
- hypogonadotrophic: caused by a secondary (hypothalamic or pituitary) disorder that reduces production of gonadotrophins (luteinising hormone [LH] and follicle stimulating hormone [FSH]). This diminishes stimuli to the ovaries to produce hormones and oocytes.
- hypergonadotrophic: caused by a primary (ovarian) disorder that reduces hormone (estrogen, progesterone and testosterone) and oocyte production; this reduces negative feedback on production of LH and FSH, causing LH and FSH concentrations to rise.
Patient information on normal menstruation and causes of amenorrhoea is available from: