This multicenter prospective cohort study evaluates the clinical efficacy and safety of dydrogesterone versus drospirenone and ethinylestradiol in adolescents aged 10-19 years with abnormal uterine bleeding-ovulatory dysfunction (AUB-O). Patients who meet the FIGO PALM-COEIN criteria for AUB-O, have complete baseline clinical data, and provide guardian consent with adolescent assent are enrolled. Participants are allocated to receive either dydrogesterone or drospirenone and ethinylestradiol according to routine clinical practice. The primary outcome is the 6-month menstrual normalization rate (cycle length 21-35 days). Secondary outcomes include breakthrough bleeding, recurrence, adverse events, and quality-of-life improvements. Follow-up is conducted during treatment and for 6 months after treatment cessation, during which menstrual normalization is evaluated based on changes in menstrual cycle patterns and examination findings. The findings may help clarify the comparative effectiveness and safety of these two hormonal regimens for long-term cycle management in adolescents with AUB-O.

This multicenter prospective cohort study evaluates the clinical efficacy and safety of dydrogesterone versus drospirenone and ethinylestradiol in adolescents aged 10-19 years with abnormal uterine bleeding-ovulatory dysfunction (AUB-O). Patients are included if they meet the International Federation of Gynecology and Obstetrics (FIGO) PALM-COEIN criteria for AUB-O, have complete baseline clinical data (complete blood count, serum ferritin, thyroid function, sex hormone panel, coagulation profile, and pelvic ultrasonography), and provide guardian consent with adolescent assent. Patients with uncontrolled coagulation disorders, unstable endocrine conditions (e.g., untreated thyroid dysfunction or hyperprolactinemia), significant hepatic or renal impairment, or known hypersensitivity to progestins are excluded. Eligible participants are allocated to receive either dydrogesterone or drospirenone and ethinylestradiol according to routine clinical practice. The primary objective is to compare the 6-month menstrual normalization rate (cycle length 21-35 days) between the two groups. Secondary objectives include changes in menstrual blood loss, hemoglobin and ferritin levels, recurrence after treatment discontinuation, time to hemostasis, quality-of-life improvements (assessed by the adolescent-version menstrual bleeding questionnaire), and safety outcomes (adverse events and laboratory monitoring). Follow-up at 6 months focuses on menstrual normalization and quality-of-life improvement. Clinical, demographic, and disease-related characteristics (age, age at menarche, body mass index, baseline bleeding severity, anemia and iron status, endocrine/metabolic factors, adherence, and family support) are collected from medical records and visit data. Because this is an observational cohort study, no intervention is randomly assigned; treatment decisions are based on standard clinical practice. The study aims to assess the comparative effectiveness and safety of the two hormonal regimens for long-term cycle regulation in adolescents with AUB-O. Multivariable regression and propensity score weighting will be used to adjust for potential confounders and center effects, with subgroup and sensitivity analyses, and multiple imputation for missing data. The results are expected to provide real-world evidence to guide hormonal management in this population.

Inclusion Criteria:

• Female patient between 10-19 years old, already experiencing menarche and at least 6 months away from menarche
• According with the criteria of Abnormal Uterine Bleeding of Ovulatory Disorders: irregular menstrual cycles (cycle interval<21 days or>45 days, or adjacent menstrual intervals>90 days), prolonged menstrual periods (>7 days), excessive menstrual flow, poor bleeding control (score>100 on the menstrual bleeding assessment scale, or a significant increase in the frequency of changing hygiene products) within the past 3 months, and has ruled out pregnancy related and obvious structural causes.
• The guardian of the subject signs the informed consent and obtains the consent of the subject.
• With complete baseline clinical data: complete blood count, serum ferritin, Six types of sex hormones(FSH, LH, E2, P, T, PRL), Gynecological Sonography.

Exclusion Criteria:

• Coagulation disorder
• Requiring long-term anticoagulant and antiplatelet therapy
• Secondary Abnormal Uterine Bleeding caused by uncontrolled hyperthyroidism, hypothyroidism, hyperprolactinemia, or other endocrine diseases.
• Dysfunction of kidney and liver, or a history of severe intolerance or allergy to dydrogesterone, medroxyprogesterone, or other progestogens.

Female participants aged 10 to 19 years old with Abnormal Uterine Bleeding of Ovulatory Disorders will be enrolled.