In India Duphaston is approved and widely used for the treatment of progesterone deficiencies such as for management of dysmenorrhea, endometriosis, secondary amenorrhea, irregular cycles, dysfunctional uterine bleeding, pre-menstrual syndrome, threatened and habitual abortion, infertility due to luteal insufficiency, as well as part of hormone replacement therapy. One Indian study reported normalization of the cycle in 91.6% of women with menstrual problems after three cycles of therapy with dydrogesterone 10 mg given from 11th to the 25th day of the menstrual cycle. The mean cycle duration during dydrogesterone therapy in this study was noted to be 28.8 days, in contrast to 17.9 days (in the polymenorrhea group) and 50.6 days (in the oligomenorrhea group) before therapy. Furthermore, dydrogesterone also decreased the amount and duration of menstrual bleeding in this study.

However, there are limited data regarding Duphaston's role in achieving cycle regularization from post-marketing settings. Moreover, it is not well-known if the effect of Duphaston therapy persists after cessation of treatment and whether the persistent effect, if any, is related to the duration of Duphaston therapy.

Hence, in this observational study, given that (based on previous clinical studies as mentioned above) Duphaston plays a role in menstrual irregularities treatment, the goal is to tease out the possible implications of such treatment in terms of treatment length and response pattern.

Primary objective:

• To determine percentage of patients reporting a regular cycle (defined as cycle duration between 21 to 35 days, inclusive) at the end of treatment period.

Secondary objectives:

A. For all patients:

• To describe evolution of cycle duration from baseline to end of treatment by assessing mean cycle duration (in days) at baseline, separately in polymenorrhea, (i.e., cycle duration < 21 days) and oligomenorrhea (i.e., cycle duration > 35 days) groups, and at the end of treatment.
• To describe evolution of duration of menstrual bleeding from baseline to end of treatment by assessing mean duration of menstrual bleeding (in days) at baseline and at the end of treatment.
• To describe evolution of amount of menstrual bleeding from baseline to end of treatment, by assessing average number of pads changed per day at baseline and at the end of treatment.
• To describe evolution of pain during menstruation (on a 11 point Likert Scale where 0 means no pain and 10 means worst pain) ) from baseline to end of treatment, by assessing mean and standard deviation of pain scores at baseline and at the end of treatment.
• To describe overall patient satisfaction (on a 5 point Clinical Global Impression of Severity scale, where 1 = very dissatisfied, 2 = dissatisfied, 3 = somewhat satisfied, 4 = satisfied, 5 = very satisfied) at the end of treatment, by assessing percentages of patients in each category at the end of treatment.
• To describe overall clinical response (on a 7 point Clinical Global Impression of Severity scale, where 1 = Normal, not at all ill, 2 = Borderline mentally ill, 3 = Mildly ill, 4 = Moderately ill, 5 = Markedly ill, 6 = Severely ill, 7 = Most extremely ill) ) at the end of treatment by assessing percentages of patients in each category at the end of treatment.

B. For patients who had achieved regular cycle at the end of treatment:

• To determine the percentage of patients still experiencing regular cycle (i.e., duration 21-35 days, inclusive) at the end of follow up period, out of total number of patients who had achieved cycle regularization at the end of treatment period.
• To determine median time to relapse (defined as cycle duration < 21 days or > 35 days) during the follow up period, for patients who had achieved regular cycle at the end of treatment, using Kaplan Meier's method to graphically plot time after cessation of treatment versus percentage of patients still having regular cycles.
• To determine any correlation between treatment duration (number of cycles of Duphaston treatment received) and persistence of effect (number of months until when regular cycles are maintained after cessation of Duphaston therapy), using linear regression analysis model.
• To describe evolution of duration of menstrual bleeding from cessation of treatment to end follow up, by assessing mean duration of menstrual bleeding (in days) at end of treatment and at the end of follow up.
• To describe evolution of amount of menstrual bleeding from cessation of treatment to end follow up, by assessing average number of pads changed per day at end of treatment and at the end of follow up.
• To describe evolution of pain during menstruation (on a 11 point Likert Scale where 0 means no pain and 10 means worst pain) from cessation of treatment to end follow up, by assessing mean and standard deviation of pain scores at end of treatment and at the end of follow up.

Inclusion Criteria

• Women aged 18 years or older
• Suffering from irregular menstrual cycle for at least 3 months and for whom the physician decides to prescribe Duphaston, in accordance with locally approved package insert
• Patients willing to sign written authorization to provide data for the study

Exclusion Criteria

• Patients having known hypersensitivity to the active ingredient or excipients
• Patients having known or suspected progesterone-dependent neoplasms
• Patients having vaginal bleeding of unknown etiology
• Patients taking oral contraceptives
• Pregnant and lactating patients
• Any other condition that precludes use of Duphaston in a particular patient, in accordance with the contraindication, precautions and special warnings listed in the locally approve package insert (for example, patients with history of liver disease, porphyria or depression)
• Patients not willing to sign written authorization for data release consent form

Subjects with irregular menstrual cycle