Abstract: BACKGROUND:Timely delivery and magnesium sulfate (MgSO4) are mainstay in the treatment of preeclampsia with severe features (PWSF). Premature delivery, severity of illness and mother-infant separation may increase the risk for breastfeeding (BF) initiation failure. OBJECTIVE:To compare BF initiation among women with late-onset PWSF treated with MgSO4 to women with late-onset preeclampsia without severe features (WOSF) who did not receive MgSO4. METHODS:Retrospective study of 158 women with PWSF and 104 with WOSF who delivered at ≥34 weeks. Intention to BF, formula feed (FF) or partially BF was declared prenatally. At discharge, exclusive BF included direct BF or direct BF with expressed breast milk (EBM). RESULTS:PWSF and WOSF groups were similar in age, race, and obstetric history. PWSF and WSOF differed in primiparity (65 & 51%), late preterm births (73 vs 15%), admission to NICU (44 &17%) and mother (5 & 4d) and infant (6 & 3d) hospital stay. Both groups were similar in intention to BF (80 & 84%), to FF (16 & 13%) and to partially BF (5 & 5%). At discharge, exclusive BF (37 & 39%), partial BF (33 & 31%) and FF (30 & 30%) were similar. Exclusive BF in the PWSF group was 43% direct BF, 28% direct BF and EBM and 29% EBM alone whereas in the WOSF group exclusive BF was 93% direct BF and 7% direct BF and EBM. CONCLUSION:BF initiation rates for women with PWSF and WOSF were similar. EBM alone or with direct BF enabled infants in the PWSF group to exclusively BF at discharge.