Study of Oral Atogepant to Assess Adverse Events and Change in Disease Activity in Adult Participants With Menstrual Migraine

Inclusion Criteria: * History and eDiary confirmation have regular menstrual cycles within the range of 21 to 35 days in length (Note: menstrual cycle length is calculated as onset of menses until the day before the next onset of menses). * History of migraine (with or without aura) according to the International Classification of Headache Disorders, 3rd Edition (ICHD-3) for \>= 12 months prior to Visit 1/Screening. * Migraine onset before age 50 years. * By history at Visit 1/Screening, participant meets ICHD-3 criteria for pure menstrual migraine with or without aura, or menstrually-related migraine with or without aura, i.e., in at least 2 out of 3 cycles, experiences migraine attacks starting during the PMP (Day -2 to Day +3 relative to menses onset) in the opinion of the investigator. * Participant records 3 perimenstrual periods (PMP) in the eDiary during the screening period, and in at least 2 of 3 PMPs the participant experiences and records a migraine attack in the eDiary with at least 1 migraine day. Exclusion Criteria: * History of an average of 15 or more headache days per month during the 3 months prior to Visit 1/Screening per the investigator's judgment, or a current diagnosis of chronic migraine as defined by International Classification of Headache Disorders, 3rd Edition (ICHD-3). * An average of 15 or more headache days per month recorded in the eDiary during the screening period. * History of migraine with brainstem aura, hemiplegic migraine, or retinal migraine as defined by ICHD-3. * Current diagnosis of new persistent daily headache, trigeminal autonomic cephalalgia (e.g., cluster headache), or painful cranial neuropathy as defined by ICHD-3. * Required hospital/emergency room treatment for migraine attacks 3 or more times within 6 months prior to Visit 1/Screening. * Presence of other confounding pain syndromes, confounding psychiatric conditions, dementia, epilepsy, or significant neurological disorders other than migraine per investigator judgment. * Has a condition or situation, which the investigator feels will compromise the safety of the participant or the quality of the data and renders the subject an unsuitable candidate for the study.