Due to reduced rate of egg production and several disorders caused by hormonal imbalances
Explanation:
Women lose their fertility at the age of 45 while men are able to produce sperm throughout their life. The reasons however for this are not very clear but it has been found that the rate of production of egg decreases with the advancement of age of females. Also the quality of egg degrades thereby reducing the likelihood of an egg being genetically normal. A woman along with faces several disorders due to the hormonal imbalances and one of these disorders is PCOS, ovarian insufficiency etc., which lead to distorted pattern of menstrual cycle.
