We read with interest the recent report of Jolies and Hoehn-Velasco 1 concerning the value of The Joint Commission breastfeeding exclusivity perinatal core measure and Baby-Friendly certification, as an effective quality strategy and associated "lever" driving performance improvement and enhanced population health.The authors focus their analysis on the incidence of breastfeeding persistence at 6 and 12 months after discharge and breastfeeding exclusivity in the first 2 days of life, using publicly reported data from the National Immunization Survey and the Centers for Disease Control and Prevention (CDC) Breastfeeding Report Cards. As a measure of success, they report that between 2008 and 2014, there was an increase in the percentage of births in certified (ie, designated) Baby-Friendly hospitals in the United States from 2.4% to 7.0%, with associated increases in breastfeeding rates at 6 to 12 months, which they imply resulted from the increase in Baby-Friendly designated hospitals.Given the demographic and cultural heterogeneity of the United States and its territories, as well as the varied approaches to supporting breastfeeding of state and hospital programs throughout the nation, we suggest that using aggregated national data to determine the relationship between breastfeeding rates following postnatal hospital discharge and Baby-Friendly Hospital designation is not appropriate. The small national penetrance of 7.0% of births in hospitals with Baby-Friendly designation strongly supports the ecological fallacy of this approach. During the same time frame, breastfeeding initiation increased from 74.5% to 80.6%, a much larger national penetrance and a more logical explana-Disclosure: Dr Kleinman reports receiving payment for serving as a coeditor for the American Academy of Pediatrics book, Pediatric Nutrition, 8th edition.