The following factors have been identified that lead to Abnormal Uterine Bleeding (AUB): 

1. Hormonal imbalances: Fluctuations in estrogen and progesterone levels can affect the growth and shedding of the uterine lining, leading to abnormal bleeding patterns. Conditions such as polycystic ovary syndrome (PCOS), thyroid disorders, and hormonal contraceptive use can contribute to hormonal imbalances and AUB.
2. Anovulation: A common cause of AUB is anovulation, where the ovaries fail to release an egg during the menstrual cycle. In anovulatory cycles, the endometrium (uterine lining) may become thicker and unstable, leading to prolonged or heavy bleeding.
3. Structural abnormalities: Structural abnormalities of the uterus or cervix can cause AUB. Conditions such as uterine fibroids, polyps, adenomyosis, uterine and cervix malignancies and other cervical abnormalities can disrupt the normal menstrual flow and lead to abnormal bleeding. 
4. Blood clotting disorders: Some individuals with AUB may have underlying blood clotting disorders, such as von Willebrand disease or platelet dysfunction. 
5. Systemic diseases and medications: Certain systemic diseases, such as liver or kidney disease, and certain medications, such as anticoagulants or hormone medications, can contribute to AUB. 
Diagnosing the underlying cause of AUB requires a thorough evaluation by a Gynaecologist, including medical history, physical examination, and often additional tests such as blood work, imaging, or endometrial sampling. Treatment options for AUB depend on the underlying cause and may include hormonal therapies, non-hormonal medications, minimally invasive procedures, or, in some cases, surgery.