INS and Infertility: PCOS is the leading cause of infertility and menstrual irregularities in women ofreproductive age and is characterised by chronic hyperandrogenic anovulation [90].This is thought to be due, in general, to hypothalamic-pituitary axisdysregulation causing elevated basal LH levels that overstimulate cells of thetheca interna [91].Insulin resistance also appears to contribute to the syndrome in many instances[92],as the pituitary responds to elevated plasma levels of insulin to augment LHrelease [91].