Table 1.

Characteristics of the included studies (alphabetically by author).

Authors	Study Design	Sample Size, Sample (Population)	Setting (Context)	Country	Collection Period	Phenomenon of Interest	Sustainability Factors	Quality
Alencar and Seidl (2010) [26]	Cross-sectional	36 human milk donors	Two human milk banks of the public health system of the Federal District	Brazil	May 2005–November 2006	The categories for the reasons (factors)of influencing the frequency of expressing and milk production were the ingestion of liquids, diet, routines of the mother going out, contraceptive use and return to work, baby feeding frequency, the presence of negative emotions, availability of time, frequency of expressing, growth of the baby, period of the day, physical fatigue and laziness, and nothing interfering with production.	Donors’ frequency of milk extraction and milk production	Weak *
Bocci et al. (2019) [27]	Cross-sectional	304 human milk donors	A human milk bank in the province of Siena	Italy	January 2010–August 2017	Factors related to the volume of milk donated: length of donation period and gestational age (preterm delivery).	Volume of milk donated	Good *
Jarmoc et al. (2021) [28]	Cohort study	3764 human milk donors (with a total of 10,525 donations)	Mothers’ Milk Bank Northeast (MMBNE), a non-for-profit milk bank located in Newton Upper Falls, Massachusetts	USA	1 January 2011–1 September 2019	Factor related to the volume of milk donated: whether the mother had a preterm or a term infant.	Volume of milk donated	Good *
Machado et al. (2015) [29]	Qualitative	7 human milk donors	A human milk bank located in the Virgen de las Nieves hospital, Granada	Spain	May–June 2013	Factors that influence women to continue donating their milk: milk bank support and family support of donation.Obstacles for women to remain donors: distance to the milk bank, support at work, and reduction in milk by the process of breastfeeding itself.	Facilitators and barriers to donation continuation	Good **
Mondkar et al. (2018) [30]	Qualitative	56 service recipients, including human milk donors and key influencers, as well as 9 service providers	Two health facilities under the Mumbai Municipal Corporation were purposively selected as case studies: a Level III facility with a human milk bank and a Level II facility without one.	India	August–November 2016	service providers reported a factor that could be a barrier to sustaining an adequate supply of DHM: staff shortage.	Volume of milk donated	Good **
Nangia et al. (2020) [31]	Cross-sectional	1553 human milk donors	The human milk bank of a tertiary care centre in a low- and middle-income country	India	7 June 2017–28 February 2019	The volume of the donor milk collected is influenced by the service in which the baby is hospitalized (neonatal intensive care unit versus postnatal care ward).	Volume of milk donated	Moderate *
Osbaldiston & Mingle (2007) [32]	Cross-sectional	87 human milk donors and 19 non donors (women who had pumped milk while breastfeeding their infants).	Mothers’ milk bank at Austin (Texas)	USA	Fall 2005–spring 2006	Factors of interest apparently related to the amount of milk donated: thrush (in the infant); motive for donating milk (e.g., ’had too much milk and wanted to donate it’, as well as ‘needed to pump milk to stimulate lactation’); mother’s age.	Volume of milk donated	Moderate *
Pimenteira Thomaz et al. (2008) [33]	Cross-sectional	737 human milk donors	All three human milk banks in the State of Alagoas (located in the following hospitals: Maternity School Hospital Santa Mônica; Federal University of Alagoas School Hospital; Santa Casa de Misericórdia of São Miguel dos Campos).	Brazil	March 2004–February 2005	The most common characteristics of a regular donor in comparison with a first-time donor are having between four and seven pregnancies and possessing a higher education level.	Donation recurrence (first-time versus regular donors)	Moderate *
Quitadamo et al. (2018) [34]	Cross-sectional	90 women, enrolled for donation	The human milk bank of the Casa Sollievo della Sofferenza hospital, which is integrated into the Neonatology Service of the same hospital.	Italy	1 January 2014–31 December 2015	Factors related to the volume of milk donated: maternal age; birth weight of the neonate; duration of donation; profession of the donor.	Volume of milk donated	Weak *
Sierra-Colomina et al. (2014) [35]	Cross-sectional	391 human milk donors (for a total of 415 donations)	The human milk bank of the Hospital Doce de Octubre, in the Madrid community, Spanish central region.	Spain	1 January 2009–31 April 2013	Donors’ social and demographic variables related to the volume of donor milk delivered: previous donors; smaller gestational age of children; started donation at earlier stages of lactation.	Volume of milk donated	Good *

*: Quality appraisal of cross-sectional and cohort studies performed with the National Heart, Lung, and Blood Institute checklist. **: Quality appraisal of qualitative studies performed with the CASP qualitative checklist.