Objective To synthesise what is known about the parents’ views on factors that help or hinder breast milk supply during their infants’ hospitalisation in neonatal intensive care units (NICU).

Methods A systematic search of PubMed, ISI WoK, PsycINFO and SciELO, targeting studies presenting original empirical data that examined parents’ perspectives regarding breast milk supply experiences in NICU, was performed. Based on content analysis, three independent researchers synthesised the findings of seven studies. Categories of facilitators and barriers were identified using quotations stated in the studies: parents’ breast milk supply experience; parents–professionals relationships; characteristics of the NICU; and parents’ social background and expectations.

Results The studies, five qualitative and two mixed methods, were published between 1994 and 2011. With heterogeneous study designs, fathers’ perspectives were analysed in one article. Only one study defined breastfeeding. According to parents’ perspectives, successful breast milk supply in NICU depends on coherent and accurate knowledge about its techniques and benefits, reinforcement of mothers’ motivation and alignment between NICU's routines and parents’ needs. Parents perceived issues related to their own current breast milk supply experience, simultaneously, as main facilitators and barriers. Parents–professionals relationship constituted the second group of facilitators, but the fourth of barriers. The characteristics of the NICU were more relevant as a barrier than as a facilitator.

Conclusions Although parents’ perspectives are grounded on individual child-focused experiences, their emphasis on learning and motivation guided by short-term goals opens room to the collective intervention of experts. This may facilitate the engagement of mothers, fathers and health professionals on family-centred care.