A Study to Test if Fremanezumab is Effective in Preventing Chronic Migraine in Participants 6 to 17 Years of Age

Inclusion Criteria: * The participant has a clinical history of recurrent headache consistent with the diagnosis of migraine for at least 6 months before screening, consistent with ICHD-3 criteria (Headache Classification Committee of the IHS 2013), and a history of ≥15 headache days per month on average during the 3 months prior to screening (visit 1). * The participant or parent/caregiver maintain a prospectively collected headache diary NOTE: Additional criteria apply; please contact the investigator for more information. Exclusion Criteria: * The participant is using medications containing opioids (including codeine) or barbiturates (including Fiorinal®, Fioricet®, or any other combination containing butalbital) for the treatment of migraine during the 3 months prior to the day of the screening visit. * The participant has used an intervention/device (eg, scheduled nerve block or transcranial magnetic stimulation) for the treatment of migraine or in the head or neck area for any condition during the 2 months prior to the day of the screening visit. * The participant has a current history of a clinically significant psychiatric condition, at the discretion of the investigator. Any prior history of a suicide attempt, or a history of suicidal ideation with a specific plan within the past 2 years must be excluded. * The participant has an ongoing infection or a known history of human immunodeficiency virus infection, tuberculosis, Lyme disease, or chronic hepatitis B or C…