Severe maternal morbidity (SMM) refers to life-threatening complications of labor and delivery that result in significant short- or long-term health consequences. SMM data are derived from linking NYC birth certificates for births occurring at NYC facilities with the mother's delivery hospitalization record from the New York Statewide Planning and Research Cooperative System. SMM is identified using an established algorithm developed by the Centers for Disease Control and Prevention that comprises 21 indicators that represent diagnoses of serious complications of pregnancy or delivery or procedures used to manage serious conditions. Each record represents the aggregated number and rate of SMM events in the population group specified for the year specified.