RecruitingPhase 4Drug trialA Study to Measure Mirikizumab Levels in Breast Milk of Lactating Participants Receiving Mirikizumab Therapeutically for an Approved IndicationThe main purpose of this study is to assess the amount of mirikizumab in breast milk in women who are breastfeeding who are receiving stable maintenance doses of mirikizumab for an approved indication. Participation in this study could last up to 94 days, including screening and follow-up period.