Disorders of ovulation

A regular ovulatory menstrual cycle requires a functional and integrated feedback system involving the hypothalamus, the anterior pituitary and the ovary (Figure 1). In the normal menstrual cycle, periods occur at regular intervals of 21-35 days and bleeding lasts for up to 7 days. Disorders of ovulation usually cause menstrual disturbance and present with irregular periods (oligomenorrhoea) or absent periods (amenorrhoea). Irregular periods with anovulatory cycles are commonest under age 20 and over age 40. Ovulatory disorders account for one-quarter of couples presenting with infertility. Anovulation may be classified by the anatomical location of the defect in the hypothalamo-pituitary-ovarian axis (Figure 2). By focusing on ovarian, hypothalamic and endocrine defects, this article offers an overview of the disorders of ovulation.