AbstractObjectiveTo evaluate the impact of the Baby-Friendly Hospital Initiative (BFHI) on breast-feeding initiation and duration overall and according to maternal education.DesignQuasi-experimental study using data from five states (Alaska, Maine, Nebraska, Ohio, Washington) that participated in the Pregnancy Risk Assessment Monitoring System from 1999 to 2009. Using differences-in-differences models that included year and hospital fixed effects, we compared rates of breast-feeding initiation and duration (any and exclusive breast-feeding for ≥4 weeks) before and after BFHI accreditation between mothers who gave birth in hospitals that were accredited or became accredited and mothers from matched non-BFHI facilities. We stratified analyses into lower and higher education groups.SettingThirteen BFHI hospitals and nineteen matched non-BFHI facilities across five states in the USA.SubjectsMothers (n 11 723) who gave birth in BFHI hospitals and mothers (n 13 604) from nineteen matched non-BFHI facilities.ResultsAlthough we did not find overall differences in breast-feeding initiation between birth facilities that received BFHI accreditation compared with non-Baby-Friendly facilities (adjusted coefficient = 0·024; 95 % CI −0·00, 0·51), breast-feeding initiation increased by 3·8 percentage points among mothers with lower education who delivered in Baby-Friendly facilities (P = 0·05), but not among mothers with higher education (adjusted coefficient = 0·002; 95 % CI −0·04, 0·05). BFHI accreditation also increased exclusive breast-feeding for ≥4 weeks by 4·5 percentage points (P = 0·02) among mothers with lower education who delivered in BFHI facilities.ConclusionsBy increasing breast-feeding initiation and duration among mothers with lower education, the BFHI may reduce socio-economic disparities in breast-feeding.