Perspectives and factors associated with informal human milk sharing: a mixed-methods systematic review protocol.

Background: The practice of informal human milk sharing is a relatively new phenomenon and poses significant questions in the domain of infant feeding. Informal human milk sharing is a means of donating human milk from another lactating individual who is not the child's biological parent, in a casual manner, that is, without the involvement of health professionals or agencies. The advent of digital technology has facilitated the donation and receipt of human milk through digital online platforms and thus has amplified this modern practice. This research aims to comprehensively examine and synthesize evidence about the motivations, barriers, facilitators and experiences of individuals who both donate (donors) and the primary care givers of the infants who receive (recipients) human milk informally to provide to infants.

Methods: A mixed-methods systematic review will be undertaken. This review will consider qualitative, quantitative and primary mixed-methods studies which report on the factors associated with informal milk sharing, and on donors' and recipients' experiences of the practice. Primary mixed-method studies will be included if the individual qualitative and quantitative components can be extracted. Five databases will be searched for studies on informal human milk sharing published from inception of the database. Study quality will be evaluated using the standardized JBI critical appraisal tools, selected based on the methodology in each individual study. Data extraction will be conducted using the JBI mixed methods data extraction form followed by data transformation, synthesis and integration. This mixed-methods systematic review will follow a convergent integrated approach in accordance with JBI guidance.

Discussion: Informal human milk sharing is a novel practice in the domain of infant feeding. This review will enable a thorough understanding of this practice from both the donors and recipients' perspective and will have implications for healthcare professionals, policy and future clinical decision-making.

Protocol registration number: PROSPERO CRD42023405653.