Ovulation is the release of an ovum (egg) from a woman’s ovary. This occurs monthly, about 14 days before the next menstrual period, and continues regularly from puberty to menopause.
Ovulation is stimulated by changes in the levels of follicle stimulating hormone and luteinising hormone, both of which are produced in the pituitary gland.
Ovulation may cease with the use of contraceptive pill or other hormonal contraceptives, and a wide range of medical and lifestyle conditions. These include:
- pregnancy (so obvious, but sometimes forgotten to the embarrassment of both doctor and patient);
- emotional trauma (e.g. loss of job, death in family);
- physical stress (e.g. vigorous athletic training);
- serious illness (e.g. major infection);
- poor nutrition (e.g. lack of food, vomiting and diarrhoea);
- significant weight loss as a result of deliberate dieting,
- disease (e.g. cancer),
- psychiatric disturbance (e.g. anorexia nervosa);
- tumours, cysts or cancer in an ovary that affect the regular cyclical production of oestrogen;
- pituitary gland disorders;
- a lack of thyroxine (hypothyroidism);
- Asherman syndrome;
- Addison’s disease;
- the Stein-Leventhal syndrome;
- Turner syndrome
- congenital adrenal hyperplasia (adrenogenital syndrome) which affects the adrenal glands that sit on top of each kidney and stimulates them to produce abnormal steroids in the body, affecting sexual development.
If the menstrual periods cease it may be due to a failure of ovulation or pregnancy.