Observational Study of Dydrogesterone in Cycle Regularization

Inclusion Criteria: * Women aged 16 years or above with menses * Patient who is suffering from irregular menstrual cycle for at least 3 months and has been diagnosed as AUB-O (irregular cycle is defined as cycle duration \< 21days or \>35 days) * Physicians have decided to prescribe dydrogesterone 10mg for cycle regulation treatment, orally taking dydrogesterone 10mg twice daily, from day16 to day 25 of each cycle, being consecutive at least 3 cycles * Patient who is willing to sign written authorization Exclusion Criteria: * Hyperprolactinemia and thyroid dysfunction. * Patient took cycle regulation treatment including oral contraceptives, sex hormone or glucocorticoid in the past 1 month * Women with estrogen deficiency related symptom * Patient who meets the contraindications listed in Chinese label of dydrogesterone * Pregnant and lactating patients * Patient who is not suitable for the study according to physician's discretion