Northwestern, Centegra push forward on merger May 8, 2018 | HNI Stories, Hospitals, Top Stories Northwestern Memorial HealthCare and Centegra Health System are asking state officials to approve a merger they first announced more than two years ago.To access this content, you must purchase 1 Year Health News Illinois Subscription or 1 Year Group Subscription - Up to 5 Users, or log in if you are a member.