Current Trends in Research on Human Milk Exchange for Infant Feeding

Donation barriers, enablers, patterns and predictors of milk bank donors in the United States and United Kingdom

Pasteurised donor human milk is recommended for very low birthweight infants who do not have access to their mother's milk. Although the use of donor milk continues to increase, little is known about the donation experiences of milk bank donors. We aimed to describe and compare enablers, barriers and patterns of human milk donation and identify factors predicting donation volume in a convenience sample of approved milk bank donors in the United Kingdom and the United States. A cross-sectional online survey was conducted from August 2022 to December 2022. Approved milk bank donors (n = 556) from three milk banks in the United States (n = 369, Mothers' Milk Bank of Florida, Mother's Milk Bank of North Texas and Northwest Mothers Milk Bank) and one milk bank in the United Kingdom (n = 187, Hearts Milk Bank) completed the survey. A substantial portion of donors in both settings reported participating in other forms of milk exchange (51% of U.S. donors vs. 39% of UK donors, p = 0.009). Top donation barriers reported in both settings were completing the serological screening and having enough space to store collected milk. Most donors started donating when their infant was 3 months old or older and reported donating mature milk. The most common source of information related to milk banking in each setting was the internet (United Kingdom-70% vs. United States - 63%, p = 0.112). Variables that predicted lifetime donation volume differed between the United States and the United Kingdom, highlighting the importance of setting-specific milk banking research.

Maternal transmission as a microbial symbiont sieve, and the absence of lactation in male mammals

Gut microbiomes of mammals carry a complex symbiotic assemblage of microorganisms. Feeding newborn infants milk from the mammary gland allows vertical transmission of the parental milk microbiome to the offspring's gut microbiome. This has benefits, but also has hazards for the host population. Using mathematical models, we demonstrate that biparental vertical transmission enables deleterious microbial elements to invade host populations. In contrast, uniparental vertical transmission acts as a sieve, preventing these invasions. Moreover, we show that deleterious symbionts generate selection on host modifier genes that keep uniparental transmission in place. Since microbial transmission occurs during birth in placental mammals, subsequent transmission of the milk microbiome needs to be maternal to avoid the spread of deleterious elements. This paper therefore argues that viviparity and the hazards from biparental transmission of the milk microbiome, together generate selection against male lactation in placental mammals.

Caffeine Concentrations in Human Milk Donated to a Human Milk Bank in Japan

BACKGROUND

Human milk banks have been established to provide human milk to preterm infants who are unable to obtain milk from their mothers. Donor screening methods vary, and prospective donors are commonly screened for drug and recreational substance use through behavioral screening. Although the risk of illegal drug consumption in Japan is extremely low, caffeine may be consumed unknowingly and can be found in human milk. To date, only a few reports have been conducted on the concentration of caffeine in donor milk.

RESEARCH AIM

This study aimed to examine the pre-pasteurization levels of caffeine in human milk donated to a milk bank in Japan.

METHODS

This was a cross-sectional, observational study of caffeine concentrations in human milk donated to a human milk bank in Japan. Caffeine concentration in the donor milk was measured using high-performance liquid chromatography.

RESULTS

Caffeine was detected in 70% of the donor milk samples (N = 350). The median (range) of caffeine concentration was 0.46 [< 0.10, 7.54] mg/L, and 64.0% of the samples had less than 1 mg/L of caffeine. The caffeine concentration varied widely among as well as within individuals.

CONCLUSION

The average caffeine concentration in Japanese donor milk samples was higher than that previously reported in samples from Spain, but the range was similar. Donors should be informed that caffeine intake should be within a moderate range, to further increase the safety of donor milk.

Factors associated with informal human milk sharing among donors and recipients: A mixed-methods systematic review

BACKGROUND

The multiple benefits associated with the provision of human milk exceed individual health outcomes, engendering substantial economic, societal and environmental domains. Human milk is the absolute, unparalleled source of nutrition for infants. Informal human milk sharing is a modernistic and rapidly progressing practice. No systematic review of the factors associated with this contemporary practice among donors and recipients of informal human milk sharing exists.

AIM

The aim of this review was to identify, evaluate, synthesize and integrate the evidence on the factors associated with informal human milk sharing among donors and recipients.

METHODS

A mixed methods systematic review was conducted according to the Joanna Briggs Institute methodological guidance utilizing a convergent integrated approach. The following databases were systematically searched: CINAHL, Scopus, Medline and Embase and Web of Science between inception to August 2023. A grey literature search was conducted using multiple techniques. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

Twenty-four studies were included in this review. Ten integrated findings relating to the factors associated with informal human milk sharing among donors and recipients were identified. The four integrated findings pertaining to donors included: altruistic motivation and value, resistance to commercialization and overcoming inaccessibility, uniting digital and personal connectedness and lack of awareness and acceptance of informal human milk sharing in healthcare settings. The six integrated findings relating to recipients included: maternal or infant factors, superiority and advantageous impact of breastmilk, human milk bank influences, digital connections and transparency, healthcare professional facilitation of informal human milk sharing, and professional and logistical implications.

CONCLUSION

This review highlighted a multitude of factors that motivate, facilitate and impede the practice of informal human milk sharing. Future research is required to explore these factors further within broader geographical locations to enhance the generalizability and rigor of the body of knowledge. Further studies should consider the exploration of the experiences and psychological impact of informal human milk sharing on donors and recipients. The provision of human milk to all infants is an imperative public health endeavor and thus positioning this as a key benchmark for research and practice is crucial.

Written on milk: exploring messages written on donated human-milk bags

Every so often, among the bags of breast milk sent for donation to milk banks, clear bags of milk are found that are hand decorated and accompanied by short texts written by donating mothers. In the bank labs, the milk is poured into pasteurisation containers, and the bags are thrown away. The milk comes to the neonatal ward packed in bar-coded bottles. Both donor and the recipient are anonymous to one another. To whom are the donating mothers writing their messages? What can be learnt from their writings and drawings about their lived experiences of transitioning into motherhood? In the current study I integrate theoretical content about the transition to motherhood and theories about epistolary literature, likening the milk bags to postcards and letters. In contrast to a private letter written with ink on folded paper in a closed envelope, writing on 'milk postcards' is exposed and privacy is absent. 'Milk postcards' have a double transparency: the self is reflected in the messages and the contents of the bag-breast milk, a bodily fluid from the body of the donor. From a visual analysis of 81 photos of human-milk bags with text and drawings photographed by milk banks laboratory technicians, it appears that the milk postcards serve as a 'third voice' that echoes the difficulties and the joys in the transition to motherhood, and that donors experience an imagined solidarity with unknown mothers. The milk itself serves sometimes as an image and sometimes as the background for the writing, while its colour, texture and the form in which it is frozen constitute part of the text and serve as self-testimony for the mother of her capability and of her being a nurturing mother, for both her own baby and other unknown babies.

Methionine Promotes Milk Protein Synthesis via the PI3K-mTOR Signaling Pathway in Human Mammary Epithelial Cells

Breast milk is widely considered to be the most natural, safe, and complete food for infants. However, current breastfeeding rates fall short of the recommendations established by the World Health Organization. Despite this, there are few studies that have focused on the promotion of human lactation through nutrient supplementation. Therefore, the aim of this study was to investigate the effect of methionine on milk synthesis in human mammary epithelial cells (MCF-10A cells) and to explore the underlying mechanisms. To achieve this, MCF-10A cells were cultured with varying concentrations of methionine, ranging from 0 to 1.2 mM. Our results indicated that 0.6 mM of methionine significantly promoted the synthesis of milk protein. An RNA-seq analysis revealed that methionine acted through the PI3K pathway. This finding was validated through real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting. In addition, PI3K inhibition assays confirmed that methionine upregulated the expression of both mTOR and p-mTOR through activation of PI3K. Taken together, these findings suggest that methionine positively regulates milk protein synthesis in MCF-10A cells through the PI3K-mTOR signaling pathway.

Case Report: I feel like a mother to other babies: experiences and perspectives on bereavement and breastmilk donation from Vietnam

There is a growing recognition globally that care regarding lactation following a perinatal death needs to potentially offer the opportunity for maternal donation. This article discusses this experience and perspectives from a human milk bank (HMB) in Vietnam. This is a descriptive exploratory case study that has a long tradition in both the social and health sciences. Triangulated data collection involved a review of video data, interview data with the donor, and data review for the Da Nang HMB, a Center for Excellence in Breastfeeding. We found that although it is common for mothers in Vietnam to donate breastmilk to HMBs, it is less common for this to occur following perinatal loss. We offer a descriptive case study of the maternal loss of twins and a subsequent choice to donate for approximately 1 month to the Da Nang HMB, the first HMB in Vietnam. We discuss four reasons derived from this case regarding donation following perinatal loss. (1) A strong motivation to donate breastmilk when aware of the service, (2) donating breastmilk helped her deal with grief, (3) family members supported her through this tough time and supported her decision, and (4) health staff supported her decision. While human milk sharing (e.g., wet nursing) has been practiced in Vietnam, breastmilk donation from bereaved mothers has neither been discussed nor well-researched. Because maternal grief is complex and individual, deciding to donate breastmilk is a personal decision that needs to be supported, without creating guilt for those who do not wish to donate.

Peer-to-Peer Human Milk-Sharing Among Israeli Milk Donors: A Mixed-Methods Study in the Land of Milk and Honey

BACKGROUND

Evidence is lacking on the phenomenon of peer-to-peer human milk-sharing in the Middle East, specifically, in Israel.

RESEARCH AIMS

This study aimed to uncover peer-to-peer human milk-sharing in Israel, learn about how and whether donors engage in safe milk handling and storage practices, and assess knowledge about human milk and breastfeeding among this milk-sharing population. We also aimed to investigate donors' selectiveness in their decisions about to whom they donate their milk and their perceptions about the sale and purchase of human milk.

METHODS

We conducted a semi-structured online survey, including both closed- and open-ended questions and used mixed methods to analyze responses descriptively. We used non-probability sampling to obtain a broad sample of human milk donors.

RESULTS

Out of 250 completed surveys, most participants (87.2%, n = 218) reported engaging in safe milk-sharing practices and were generally knowledgeable about the health risks associated with milk-sharing. Participant religiosity was associated with somewhat lower hygiene practices (r = -0.15, p ≤ .05). Most of the participants (81.7%, n = 190) were against the sale of human milk. Participants generally expressed no preference about the recipient of their milk, with some exceptions.

CONCLUSION

The milk-handling and storage practices of the participants in this study suggest a need to improve knowledge and awareness of safe milk storage temperature and the importance of washing hands before pumping milk, particularly within the religious sector. We propose that guidelines about safe milk-sharing practices be written and adopted by the Israeli Ministry of Health, and communicated through pediatricians, family doctors, nurses in Mother and Child Clinics (In Hebrew: Tipat Halav), and social media.

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.

Protecting, promoting and supporting breastfeeding in all policies: reframing the narrative

Recent research highlights the importance of breastfeeding to health across the lifecourse, yet inadequate investment to facilitate breastfeeding according to World Health Organization recommendations threatens to undermine breastfeeding's protective effects. Western media narratives often fail to convey the significance of breastfeeding, and such narratives can hinder efforts to direct sufficient resources to scaling up effective systems and generating policy change. Delayed action disproportionately harms poor and marginalized communities. The urgency of making these investments in an era of rapidly intensifying climate change and other crises is clear. Reframing the narrative is needed to better appreciate the significance of breastfeeding as well as to recognize and address extensive efforts of undermine it. Evidence-based scientific, health professional and media discussions are necessary to recognize breastfeeding as foundational to food and health security and to enact change so that protecting, promoting and supporting breastfeeding is integrated across all policies.

Maternal perceptions of human milk expression output: An experimental design using photographs of milk

BACKGROUND

The widespread use of breast pumps in the United States is a recent phenomenon that is reshaping how individuals understand and perceive lactation. In the 1990s, adequacy of milk supply was primarily measured indirectly by infant weight gain and/or diapers; now >95% of all lactating persons in the United States use breast pumps and are seeing their milk regularly. How seeing milk impacts the perception of lactation sufficiency is an important area of research. Research aim/question: To understand personal and intersubjective influences of seeing expressed human milk on perceptions of milk supply among participants who express milk for their infants.

METHODS

We surveyed 805 lactating participants from the United States about their pumping practices using an online survey. Participants described pumping practices, milk output, and beliefs. They were then randomized to view one of three photographs of expressed milk (<2 oz, 4 oz, >6oz) and asked to imagine they had just pumped that amount and provide a written response; this created 4 exposure groups (2 increase and 2 decrease) and a control group (no difference).

RESULTS

Participants randomized to a higher volume reported more positive feelings and used the terms "good", "great", and "accomplished" to describe emotional responses to output. Participants randomized to lower milk volumes reported more feelings of "bad" or "depressed." A subset of participants reported feeling "annoyed" about small volumes of milk.

CONCLUSIONS

Participants in this study were very conscious of the volume of milk pumped each session; both increases and decreases were associated with emotional responses that could contribute to decisions about pumping practices, perceived milk supply, and lactation duration.

Evolutionary biological perspectives on current social issues of breastfeeding and weaning

Breastfeeding and weaning are actively studied from evolutionary, medical, and social research perspectives because of their close association with infant mortality, lifetime health, and human population dynamics. Each discipline benefits from an interdisciplinary exchange of knowledge regarding the bases, processes, and consequences of these phenomena. However, current social issues related to breastfeeding and weaning have received little attention from an evolutionary biology perspective. We address this gap by reviewing current social issues related to human breastfeeding and weaning in an evolutionary framework. This approach helps build a conceptual framework with the goal of better understanding ultimate causes of or influences on these current social issues. The six social issues reviewed here fall into three categories: the spatiotemporal constraints of breastfeeding, abuse of breast milk as valuable material, and mismatch in breastfeeding practices. Some of these issues have an evolutionary basis. We analyze the structure of these social issues and discuss their possible solutions in terms of extension of the trade-off theory in evolutionary biology. Our discussion on the current social issues in breastfeeding and weaning highlights the effectiveness of an approach rooted in evolutionary theory and biological anthropology.

Racial Disparities in Donor Human Milk Feedings: A Study Using Electronic Medical Records

INTRODUCTION

The aim of this study was to evaluate differences in the use of pasteurized donor human milk (PDHM) by maternal race-ethnicity during postpartum hospitalization using electronic medical records (EMRs).

MATERIALS AND METHODS

A retrospective cohort study of all live-born infants at our academic research institution from July 1, 2014, to June 30, 2016, was conducted. EMR data were used to determine whether each infant received mother's own milk (MOM), PDHM, or formula. These data were stratified based on whether the infant received treatment in the Neonatal Critical Care Center. Generalized estimating equation models were used to calculate the odds of receiving PDHM by maternal race-ethnicity, adjusting for gestational age, birth weight, insurance, preferred language, nulliparity, and mode of delivery.

RESULTS

Infant feeding data were available for 7097 infants, of whom 49% were fed only MOM during their postpartum hospitalization. Among the 15.9% of infants admitted to neonatal critical care, infants of non-Hispanic Black (odds ratio [OR] 0.47, 95% confidence interval [CI] 0.31-0.72), Hispanic (OR 0.65, 95% CI 0.36-1019), and Other (OR 0.63, 95% CI 0.32-1.26) mothers had lower rates of PDHM feedings than infants of non-Hispanic White mothers in the adjusted models. Among well infants, the use of PDHM was lower among non-Hispanic Black and Hispanic mothers (OR 0.25, 95% CI 0.18-0.36, and OR 0.38, 95% CI 0.26-0.56) compared with non-Hispanic White mothers.

CONCLUSIONS

Inequities in exclusive human milk feeding and use of PDHM by maternal race-ethnicity were identified. Antiracist interventions are needed to promote equitable access to skilled lactation support and counseling for PDHM use.

Human Milk Sharing in the United States: A Scoping Review

Background: Human milk is the optimal form of infant nutrition. If mother's own milk is unavailable, families may seek alternative sources of human milk through milk sharing, despite potential health and safety risks with this practice. Objective: The purpose of this scoping review was to synthesize the current literature on human milk sharing in the United States to help health care professionals better understand how families may use this practice for infant nutrition. Methods: A systematic search was conducted in June 2021 using Ovid MEDLINE, Embase, CINAHL, ProQuest Central, Web of Science, and Google Scholar. Articles were included if the primary outcome was milk sharing, excluding milk banks and preterm hospitalized infants. Results were limited to studies conducted in the United States and published in English after January 1, 2000. Results: From 2,124 articles, 34 met inclusion criteria and were reviewed. Study designs were largely observational (30/34), and participants were predominantly white, married, and middle-income women experiencing lactation problems or in possession of excess breast milk. Milk sharing, not for profit, was often facilitated through the internet but exchanged in person. Conversely, for-profit milk sharing often involved shipping and studies found evidence of milk contamination. No studies documented infant harm. Conclusions: There is limited research on the milk quality and relative risks of milk sharing, and no research on clinical outcomes in infants fed shared milk. Clinicians have opportunities to engage in open conversations about this practice to guide risk mitigation, however, research on recipient infant outcomes are urgently needed to inform best practices.

Human milk-sharing practices and infant-feeding behaviours: A comparison of donors and recipients

Human milk sharing (HMS) is growing in popularity as an infant-feeding strategy in the United States. HMS families are a hidden population because HMS is a nonnormative and stigmatized behaviour. Thus, gaining access to HMS participants is challenging, and research on this topic remains limited. In particular, little is known about the broader infant-feeding behaviours of HMS parents. This study aimed to describe and compare the infant-feeding behaviours and HMS practices among a network of HMS donors and recipients. A detailed online survey was distributed to HMS parents in the Washington, DC region. Bivariate analyses were used to summarize the data by donor/recipient status when possible. Group differences were tested using analysis of variance for continuous variables and χ² tests for categorical variables. Donors and recipients did not differ in their sociodemographic characteristics. Recipients were significantly more likely than donors to have experienced complications of labour and delivery, traumatic birth, postpartum depression or a negative breastfeeding experience. Donors and recipients did not differ significantly in their duration of lactation or HM-feeding. Interestingly, 30% of recipients ever produced excess milk and 21% of donors ever had difficulty producing enough milk for their child. Compared with donors, recipients faced numerous maternal health challenges, but were still able to achieve a long duration of HM-feeding. HMS recipients represent a vulnerable group who may benefit from additional psychosocial and lactation support to improve their health and breastfeeding outcomes. Additional research is needed to investigate the associations between HMS participation, infant-feeding behaviours and lactation outcomes.

The Current State of Donor Human Milk Use and Practice

Human milk contains nutrients and immune factors that promote health and growth of an infant. Donor human milk is recommended as the best alternative for infants whose mothers' breast milk is unavailable. This article describes the current status of donor human milk practice and suggests the areas of educational and research needs. Articles published in the last 10 years were reviewed, and findings were summarized under 4 themes: (1) women's knowledge and concerns about donor human milk use, (2) hospital practices, (3) cost-effectiveness, and (4) access and affordability of donor human milk. Women were concerned about donor human milk contamination, disease transmission, cost, and access to bank donor human milk, due to lack of knowledge and awareness of donor human milk benefits and its processing procedures. The absence of health care providers' support for donor human milk adds to the confusion. There is a rising trend of donor human milk use in hospitals for both healthy and vulnerable newborns and infants with varying policies on screening for donor human milk use, cost coverage, or consent procedure. However, a shortage of safe and affordable donor human milk is a barrier to its adoption. A standardized guideline is needed for hospitals regarding donor human milk implementation and cost coverage. Education programs for health care providers are needed to improve knowledge and understanding of donor human milk benefits and safety to provide guidance to parents. It is crucial to develop legislation expanding insurance coverage to achieve donor human milk equity and optimizing long-term human milk diet outcomes.

An 'incredible community' or 'disgusting' and 'weird'? Representations of breastmilk sharing in worldwide news media

Breastmilk sharing via the internet has become more popular in recent years, with a resultant increase in media attention. It is actively discouraged by public health bodies in at least three countries. We undertook a qualitative analysis of worldwide English language news media (online newspaper articles and transcripts of television and radio pieces) focusing on peer‐to‐peer breastmilk sharing during a 24‐month period (2015–2016). One hundred eleven news articles were analysed semiotically for positive (n = 49) and negative (n = 90) depictions of breastmilk sharing and the actors involved. Three countries published the majority of the articles: United States (n = 42), United Kingdom (n = 24) and Australia (n = 20). Topics associated with using shared breastmilk included perceived insufficiency, having surgery or taking medication, or the prematurity of the baby. Reports of women who gave and received breastmilk were largely positive although sometimes confused with women who sell breastmilk, who were demonised. The breastmilk itself, however, was considered as potentially contaminated and possibly dangerous; calls for action (n = 33) focused on increasing regulation and safety. Peer‐to‐peer milk sharing and the commercial availability of human milk are activities that occur within social and cultural contexts, and, as such, the ways in which they are represented in the news media reflect the ways in which they are also represented more widely in society. Increased understanding of normal infant feeding practices is needed, alongside guidance on how to better support breastfeeding. News media outlets can facilitate this through reporting risk in line with evidence. Further research should be undertaken to understand the safety of breastmilk sharing and the experience of those who participate.

Breastfeeding and the origins of health: Interdisciplinary perspectives and priorities

Breastfeeding and human milk (HM) are critically important to maternal, infant and population health. This paper summarizes the proceedings of a workshop that convened a multidisciplinary panel of researchers to identify key priorities and anticipated breakthroughs in breastfeeding and HM research, discuss perceived barriers and challenges to achieving these breakthroughs and propose a constructive action plan to maximize the impact of future research in this field. Priority research areas identified were as follows: (1) addressing low breastfeeding rates and inequities using mixed methods, community partnerships and implementation science approaches; (2) improving awareness of evidence-based benefits, challenges and complexities of breastfeeding and HM among health practitioners and the public; (3) identifying differential impacts of alternative modes of HM feeding including expressed/pumped milk, donor milk and shared milk; and (4) developing a mechanistic understanding of the health effects of breastfeeding and the contributors to HM composition and variability. Key barriers and challenges included (1) overcoming methodological limitations of epidemiological breastfeeding research and mechanistic HM research; (2) counteracting 'breastfeeding denialism' arising from negative personal breastfeeding experiences; (3) distinguishing and aligning research and advocacy efforts; and (4) managing real and perceived conflicts of interest. To advance research on breastfeeding and HM and maximize the reach and impact of this research, larger investments are needed, interdisciplinary collaboration is essential, and the scientific community must engage families and other stakeholders in research planning and knowledge translation.