Human biomonitoring without in-person interaction: public health engagements during the COVID-19 pandemic and future implications.

BACKGROUND: Public health initiatives, including human biomonitoring, have been impacted by unique challenges since the onset of the COVID-19 pandemic, compounding a decades-long trend of declining public participation. To combat low public participation rates, public health professionals often employ extensive engagement approaches including in-person interactions related to enrollment and sampling, success of which is an essential component of a statistically defensible study. The onset of the COVID-19 pandemic challenged public health programs to diversify engagement and sampling approaches, limiting direct interactions for the health and safety of the population. This study explores biomonitoring recruitment strategies through non-contact mechanisms and evaluate the application feasibility for population-based studies. METHODS: The Iowa Biomonitoring Program at the State Hygienic Laboratory developed a human biomonitoring study that utilized a multifaceted, distance-based approach. Traditional techniques, such as mailed recruitment invitations and phone-based discussions, were coupled with internet-based surveys and self-collected, shipped urine and water samples. Participation rates were evaluated by employing different mailing methods, and the demographics of enrolled participants were examined. RESULTS: This non-human contact approach achieved a nearly 14% participation rate among a rural population, well above our target rates. Our improved mailing strategy for targeting initially unresponsive participants yielded a significantly increase in the participation rates. The respondents were predominantly individuals with educational attainment of at least high school level. Among all the eligible participants, 83% submitted self-collected samples, a rate comparable to the National Health and Nutrition Examination Survey which involved in-person interviews. CONCLUSIONS: The practice of engaging a rural population during the COVID-19 pandemic by transitioning from face-to-face interactions to a combination of mailing and internet-based approaches resulted in higher-than-expected participant recruitment and sample collection rates. Given the declining trend in the response rates for population-based survey studies, our results suggest conducting human biomonitoring without direct human interaction is feasible, which provides further opportunity to improve response rates and the relevance and reach of public health initiatives.

Revisiting geophagy: An evolved sickness behavior to microbiome-mediated gastrointestinal inflammation.

Geophagy, the consumption of clay or similar substances, is known as an evolved behavior that protects vulnerable populations, such as pregnant women and children, against gastrointestinal injury. However, perplexing questions remain, like the presence of geophagy in the absence of overt gastrointestinal infection and the potential causal relationship between geophagy and iron deficiency anemia. In this review, we hypothesize that geophagy is an inflammation-mediated sickness behavior regulated via the vagus nerve. We further hypothesize that the gut microbiome plays a critical role in mediating the relationship between inflammation and geophagy. By including inflammation and the microbiome within the existing protection hypothesis, we can explain how subclinical gastrointestinal states induce geophagy. Furthermore, we can explain how gastrointestinal inflammation is responsible for both geophagy and iron-deficiency anemia, explaining why the two phenomena frequently co-occur. Ultimately, defining geophagy as a sickness behavior allows us to integrate the gut-brain axis into geophagy research.

The Effects of the Ward Environment and Language in Palliative Care: A Qualitative Exploratory Study of Victorian Nurses' Perspectives.

OBJECTIVES: The current study aimed to explore regional nurses' perspectives of how bad news is delivered and the physical, natural, social, and symbolic environments where these conversations occur. BACKGROUND: In regional hospitals within Victoria, Australia, palliative and end-of-life patients are cared for in acute wards that are often busy, noisy, and do not have a palliative psychosocial focus. On the other hand, Palliative Care Units (PCUs) have more home-like dedicated spaces, yet nearly all these facilities are in metropolitan areas. Diagnostic/prognostic (bad news) conversations about life-limiting illnesses often occur at the bedside in both environments. METHOD: Nurses providing palliative or end-of-life care in regional or metropolitan Victorian hospital inpatient wards were invited to interview and recruited through social media and snowballing. Six semi-structured, audio-recorded online interviews were conducted between March and May 2022, and themes were developed using reflexive thematic analysis. RESULTS: Semi-structured online interviews were conducted with six female, registered nurses, four of whom worked in regional Victorian hospitals and two in metropolitan PCUs as Nurse Unit Managers. Three central themes were developed: "conducting family meetings," "palliative care practice," and "the environment matters." CONCLUSIONS: A therapeutic environment for palliative patients and their families consists of home-like ambience and aesthetics and a psychosocial environment created by staff who can provide holistic palliative care. Holistic palliative care requires mentoring and mirroring of expert practice to increase the expertise and capacity of the palliative care workforce in acute general hospital wards.

Patient and family members' experiences with language and environment when receiving bad news: A qualitative exploratory study.

OBJECTIVES: Receiving bad news about one's health can be devastating, yet little is known about how the therapeutic nature of the environment where bad news is delivered affects the experience. The current study aimed to explore how patients and their families were affected by the language and the built, natural, social, and symbolic environments when receiving bad news, through the Therapeutic Landscapes theoretical framework. METHODS: Patients diagnosed with a life-limiting illness living in regional Victoria who had a hospital admission within 24 months and a diagnostic/prognostic conversation were invited to participate, as well as a family member who witnessed the conversation. Participants were recruited through social media and snowballing, resulting in 14 online semi-structured interviews being conducted between November 2021 and March 2022, audio-recorded, and transcribed verbatim. Reflexive thematic analysis was used to develop the themes. RESULTS: Fourteen semi-structured interviews were conducted with women aged between 30 and 77 years. Interviews lasted between 45 and 120 minutes, with an average of 69 minutes, and were conducted online or via mobile phone. Four central themes were developed: "Hearing bad news for the first time," "Preferences for having hard conversations," "Creating a sense of safety for ongoing care," and "The therapeutic nature of the ward." SIGNIFICANCE OF RESULTS: This body of work will help inform practice and future policy regarding bad news delivery and the design and aesthetics of environments where bad news is delivered. It is essential that bad news is delivered within a quiet, calm, and emotionally safe environment within a supportive therapeutic relationship.

Postnatal growth and gut microbiota development influenced early childhood growth in preterm infants.

Background: Preterm infants are at high risk for growth failure and childhood weight problems due to the disruption of normal intrauterine growth and nutrition. Early nutritional support and microbiome acquisition can play an important role in childhood growth. Objective: Our study examined potential postnatal indicators, including gut bacterial compositions, macronutrients, and catch-up growth, of growth pattern from infancy into early childhood. Methods: This is a retrospective study of preterm infants born < 35 weeks who were followed up in the university complex care clinic from 2012-2018. Weight and length z-scores at birth, 1, 2, 4, 6, 12 and 15 months, and body mass index (BMI) and length z-scores from 2 to 5 years of age were collected. Catch-up growths were calculated by changes in z-scores and divided into early (birth-4 months) and late (4-18 months). Postnatal nutritional data and fecal samples were collected. Fecal microbiome data obtained from 16S RNA V4 sequencing was analyzed against clinical and growth data using a regression model. Results: 160 infants included in the final analysis had birth weight and gestational age of 1,149 ± 496 grams and 28 ± 3 weeks. Early weight gain positively correlated with length z-scores but not with BMI at 2 years of age. BMI at 2 years of age strongly correlated with BMI at 3, 4, and 5 years of age. Postnatal abundance of Gammaproteobacteria was negatively associated with early growth while Bacteroides and Lactobacillus were positively associated with childhood BMI. Conclusion: Our findings suggest that optimal postnatal nutrition promoted early catch-up growth in weight as well as improved linear growth without influence on childhood BMI. Postnatal gut microbial colonization, which is a modifiable factor, was associated with childhood growth in preterm infants.

Doula Perspectives on Lactation Education and Breastfeeding Support for Diverse, Low-income Women: A Field Report.

Women living below the federal poverty level have low breastfeeding rates and historically have lacked access to doula care. This disparity is particularly evident among African American women. The objective of this pilot study was to assess doulas' experiences delivering lactation education to racially/ethnically diverse, primarily Medicaid-eligible pregnant women and describe doulas' perceptions of client barriers to breastfeeding. We also wanted to understand doulas' views of infant feeding and lactation education during their participation in a quality improvement intervention that trained doulas to provide lactation education and breastfeeding support at 4 clinics serving low-income clients. Two focus groups were conducted with 7 doulas. Focus group data were transcribed, coded, and analyzed using qualitative thematic analysis. Doulas reported close relationships with their clients and provided consistent breastfeeding support and education to women in prenatal, birth, and postpartum phases of care. Doulas emphasized the need for more lactation education, especially to overcome clients' perceived milk insufficiency and early termination due to breastfeeding barriers. Doula-led breastfeeding education and support may improve breastfeeding outcomes for diverse women from underserved areas.

The experiences of health professionals, patients, and families with truth disclosure when breaking bad news in palliative care: A qualitative meta-synthesis.

OBJECTIVE: Disclosing the truth when breaking bad news continues to be difficult for health professionals, yet it is essential for patients when making informed decisions about their treatment and end-of-life care. This literature review aimed to explore and examine how health professionals, patients, and families experience truth disclosure during the delivery of bad news in the inpatient/outpatient palliative care setting. METHODS: A systemized search for peer-reviewed, published papers between 2013 and 2020 was undertaken in September 2020 using the CINAHL, Medline, and PsycInfo databases. The keywords and MeSH terms ("truth disclosure") AND ("palliative care or end-of-life care or terminal care or dying") were used. The search was repeated using ("bad news") AND ("palliative care or end-of-life care or terminal care or dying") terms. A meta-synthesis was undertaken to synthesize the findings from the eight papers. RESULTS: Eight papers were included in the meta-synthesis and were represented by five Western countries. Following the synthesis process, two concepts were identified: "Enablers in breaking bad news" and "Truth avoidance/disclosure." Several elements formed the concept of Enablers for breaking bad news, such as the therapeutic relationship, reading cues, acknowledgment, language/delivery, time/place, and qualities. A conceptual model was developed to illustrate the findings of the synthesis. SIGNIFICANCE OF RESULTS: The conceptual model demonstrates a unique way to look at communication dynamics around truth disclosure and avoidance when breaking bad news. Informed decision-making requires an understanding of the whole truth, and therefore truth disclosure is an essential part of breaking bad news.

A critical biocultural approach to early growth in the United States.

OBJECTIVES: A critical biocultural anthropology seeks to link perspectives from social theory and ethnography to human biology. In the United States (U.S.), multiple forms of structural inequalities affect early growth, including racism and poverty. The goal of this paper is to test the effects of social inequalities on birth weight and later height in the U.S. National Health and Nutrition Survey (NHANES), and to contextualize potential pathways of embodiment that link social structure and biology. METHODS: This study used data from 8392 children ages 0-5 years from the 2005 to 2016 NHANES. Reported birth weight and measured length/height (converted to height-for-age z-scores) were used as outcome variables, while various measures of socioeconomic status and the NHANES-defined race and ethnicity categories were operationalized as social variables. Structural equation modeling (SEM) was chosen to represent the data. RESULTS: The final model represented an excellent fit to the data. Higher birth weights were associated with higher height-for-age z-scores. The Black racial category was associated with lower birth weight and higher height-for-age z-score, while the "Other" racial category was also associated with lower birth weight. The socioeconomic status factor variable was significantly associated with birth weight and height-for-age z-scores. There were also multiple indirect effects of social variables on height-for-age z-scores mediated via their effects on birth weight. CONCLUSIONS: Inequalities in race and socioeconomic status persist in birth weight and early childhood stature in the U.S. These findings can be contextualized by a critical biocultural anthropology that integrates lived experiences and pathways of embodiment.

The Physical Hospital Environment and Its Effects on Palliative Patients and Their Families: A Qualitative Meta-Synthesis.

AIM: To review the latest qualitative literature on how the physical hospital environment affects palliative patients and their families. BACKGROUND: People with a life-limiting illness may receive palliative care to improve their quality of life in hospital and may have multiple admissions as their illness progresses. Yet, despite a preference for a death at home, more than half of the dying population will receive end-of-life care in hospital. The physical hospital environment consists of ambiance, aesthetics, and architectural factors, and it is well known that the hospital's acute wards are not a homely environment. Demand is increasing for the physical environment to be improved to better meet the needs and demands of palliative and end-of-life patients and their families. METHOD: Combining thematic analysis and meta-ethnography methodologies, 12 international qualitative papers were analyzed and synthesized by the three authors. RESULTS: Findings resulted in the development of the SSAFeR Place approach that incorporates the concepts that are important to palliative and end-of-life patients and their families by describing an environment within the acute or palliative care units that feels safe, is private, customizable, and accommodates family; is a space to share with others, is homelike in ambiance and aesthetics, and is conducive for reflection. The concepts of identity, belonging, and safety are connected to the notions of home. CONCLUSIONS: To provide person-centered care and to move the focus toward the palliative approach of comfort and quality of life, attention to room size, layout, aesthetics, and ambiance is needed.

Impact of Doula-Led Lactation Education on Breastfeeding Outcomes in Low-Income, Minoritized Mothers.

Prenatal education may improve breastfeeding outcomes among low-income women. Our objective was to assess breastfeeding intentions and knowledge among women participating in doula-facilitated prenatal education classes from August 2016 to October 2017. Breastfeeding knowledge and infant feeding intentions were assessed before and after the classes. Breastfeeding rates were assessed at birth, 2-4 weeks postpartum, and 6-8 weeks postpartum. Paired t-tests tests were conducted. A total of 121 racially diverse, low-income women were enrolled. Intentions to breastfeed increased pre- to post-intervention (p = 0.007). Breastfeeding knowledge scores increased pre- to post-intervention (p <.001); specifically, among women who were exclusively breastfeeding or breastfeeding while supplementing with formula at birth (p < .001 and p = 0.046, respectively). Doula-facilitated breastfeeding education may help improve breastfeeding outcomes for low-income women.

Palliative and End-of-Life Care in the Home in Regional/Rural Victoria, Australia: The Role and Lived Experience of Primary Carers.

INTRODUCTION: Palliative support services (generalist or specialist) can provide much-needed assistance to carers who are providing palliative and end-of-life care in their homes, but access to such services in regional and rural areas of Australia is poorly understood. OBJECTIVES: This study aimed to explore the role and lived experience of primary carers who are providing palliative and end-of-life care in the home in regional/rural Victoria, Australia. METHODS: Nine female participants, of whom six were bereaved between 7 and 20 months were interviewed using a semistructured interview technique. Each interview was audio-recorded, transcribed verbatim, and analyzed thematically. RESULTS: Two themes emerged: "Negotiating healthcare systems" which described the needs for multidisciplinary supports and "The caring experience" which discussed daily tasks, relationships, mental and physical exhaustion, respite, isolation, medication management, and grief and loss. Findings show that regional/rural carers have an added burden of travel stress as well as feeling overwhelmed, isolated, and physically and emotionally exhausted. Carers would benefit from greater flexibility for short-term respite care. The engagement of specialist palliative care services assisted the participants to navigate the health care system.Some participants did not understand the value of palliative care, highlighting the need for general practitioners to conduct early conversations about this with their patients. Education is needed to build capacity within the primary palliative care workforce, confirming the importance of timely referrals to a specialist palliative care practitioner if pain or symptom control is not effectively managed. CONCLUSION: Providing palliative and end-of-life care in the home is an exhausting and emotionally draining role for unpaid, primary carers. Multiple supports are needed to sustain primary carers, as they play an essential role in the primary health care system.

Understanding the Needs of Australian Carers of Adults Receiving Palliative Care in the Home: A Systematic Review of the Literature.

Caring for someone at home requiring palliative care is an ominous task. Unless the current support systems are better utilised and improved to meet the needs of those carers, the demand for acute hospital admissions will increase as the Australian population ages. The aim of this review was to examine the needs of unpaid carers who were caring for adults receiving palliative care in their home in Australia. Methods: A systematic review of the literature was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Guidelines between 2008-2020. Results: Only Australian papers were selected due to the intent to understand carers' needs in the Australian context and 17 papers made up the final data set. Four themes emerged: 1) Perceived factors influencing caregiving; 2) Perceived impact and responses to caregiving; 3) Communication and information needs; and 4) Perceptions of current palliative support services and barriers to uptake. Conclusion: Carers reported satisfaction and positive outcomes and also expressed feeling unprepared, unrecognised, stressed and exhausted.

Predictors of interleukin-1ß and interleukin-1 receptor antagonist in infant saliva.

OBJECTIVES: This study assesses the feasibility of measuring interleukin-1ß (IL-1ß) and interleukin-1 receptor antagonist (IL-1ra) in infant salivary samples as representative of pro- and anti-inflammatory processes, and explores predictors of these biomarkers in a US population. METHODS: Data were collected from 73 US mother-infant pairs. Salivary samples were collected with an infant swab and analyzed for IL-1ß, IL-1ra, and immunoglobulin A (IgA) using ELISA. Household, maternal, infant, and anthropometric predictors were selected using stepwise regression to build final multivariate models. RESULTS: Both IL-1ß and IL-1ra can be feasibly measured in infant saliva. The predictors in the final IL-1ß model were IL-1ra and reported infant illness. IL-1ß, IgA, infant age, household income, maternal BMI, and infant weight-for-age z-score were significant in the final model for IL-1ra. CONCLUSIONS: IL-1ß and IL-ra are useful biomarkers of immune function for infants. In particular, IL-1ra has the potential to address the relationship between immune function and body composition in the mother-infant dyad.

A Scoping Review of Research on the Human Milk Microbiome.

BACKGROUND: The human milk microbiome is an emerging scientific area. Careful, accurate collection and measurement for microbial sequencing is imperative. There is controversy about a core microbiome, and little is known about factors that influence composition. Even less known are ways that the milk microbiome might seed the infant gut and affect health. RESEARCH AIM: The aim of this paper is to provide a critical appraisal of milk microbiome research. The four areas of critical appraisal were collection and measurement, composition, effects on composition, and potential health effects for infants related to the milk microbiome. METHODS: Using a PRISMA-ScR scoping review, we reviewed sources of evidence extracted from PubMed, Web of Science, CINAHL, Academic Search Complete, and PSYCHINFO data sets using the following criteria: English language, published in past 6 years, primary data, and sequencing using Next Generation Sequencing. Charting of sources of evidence included authors, title, journal year, sample, design, and results. The research questions posed were: How is human milk collected and how are the microbes identified? What is the composition and what factors affect the human milk microbiome? What is the relationship of the human milk microbiome to infant biology and health? RESULTS: The reviewed studies were quantitative, cross sectional, or longitudinal. A core microbiome may be present. The microbiome may seed the early infant gut and promote physiological functions and thus influence human health. CONCLUSIONS: We have suggested concerns about collection and measurement that lead to gaps in knowledge generation, and mechanistic studies are lacking.

Predicted Metabolic Pathway Distributions in Stool Bacteria in Very-Low-Birth-Weight Infants: Potential Relationships with NICU Faltered Growth.

Many very-low-birth-weight (VLBW) infants experience growth faltering in early life despite adequate nutrition. Early growth patterns can affect later neurodevelopmental and anthropometric potentials. The role of the dysbiotic gut microbiome in VLBW infant growth is unknown. Eighty-four VLBW infants were followed for six weeks after birth with weekly stool collection. DNA was extracted from samples and the V4 region of the 16S rRNA gene was sequenced with Illumina MiSeq. A similar microbiota database from full-term infants was used for comparing gut microbiome and predicted metabolic pathways. The class Gammaproteobacteria increased or remained consistent over time in VLBW infants. Out of 228 metabolic pathways that were significantly different between term and VLBW infants, 133 pathways were significantly lower in VLBW infants. Major metabolic differences in their gut microbiome included pathways involved in decreased glycan biosynthesis and metabolism, reduced biosynthetic capacity, interrupted amino acid metabolism, changes that could result in increased infection susceptibility, and many other system deficiencies. Our study reveals poor postnatal growth in a VLBW cohort who had dysbiotic gut microbiota and differences in predicted metabolic pathways compared to term infants. The gut microbiota in VLBW infants likely plays an important role in postnatal growth.

Contributors to Dysbiosis in Very-Low-Birth-Weight Infants.

The objective of this commentary was to analyze the causes and outcomes of gut microbiome dysbiosis in preterm infants who are born at very low birth weight (VLBW). The intrauterine development of VLBW infants is interrupted abruptly with preterm birth and followed by extrauterine, health-threatening conditions and sequelae. These infants develop intestinal microbial dysbiosis characterized by low diversity, an overall reduction in beneficial and/or commensal bacteria, and enrichment of opportunistic pathogens of the Gammaproteobacteria class. The origin of VLBW infant dysbiosis is not well understood and is likely the result of a combination of immaturity and medical care. We propose that these factors interact to produce inflammation in the gut, which further perpetuates dysbiosis. Understanding the sources of dysbiosis could result in interventions to reduce gut inflammation, decrease enteric pathology, and improve health outcomes for these vulnerable infants.

Historical Antecedents of Breastfeeding for African American Women: from the Pre-Colonial Period to the Mid-Twentieth Century.

INTRODUCTION: African American women have much lower breastfeeding rates than other racial and ethnic groups in the USA. While researchers are beginning to explore contemporary factors contributing to this inequality, much less research has been devoted to the historical conditions that have contributed to these disparities. AIM: The aim of this paper was to describe the social, economic, and political factors that have influenced African American breastfeeding behavior in the USA from the colonial era through the mid-twentieth century. METHODS: A thematic analysis was conducted across multiple databases and sources. A social history framework, which focuses on the experiences of ordinary people and events, was used to identify and integrate themes found within the reviewed literature. RESULTS: Three themes emerged: (1) Labor forces and other socio-cultural factors affected feeding practices and communal caregiving; (2) history of supplementation; and (3) influence of medicalization of birth and mobility on infant feeding in the twentieth century. These themes illustrate how African American women's ability to breastfeed has been significantly constrained throughout the U.S. HISTORY: Supplementation with non-human milk substitutes and communal caregiving helped African American women navigate infant rearing under adverse socioeconomic circumstances. CONCLUSIONS: Social, political, and economic factors have contributed significantly to African American women's ability to breastfeed throughout the U.S. HISTORY: Understanding the influences of historical antecedents on breastfeeding decisions over time may be key to finding effective interventions that might increase breastfeeding rates within this population.

Iron and fecundity among Tsimane' women of Bolivia.

BACKGROUND AND OBJECTIVES: Iron is critical for women's reproduction, and iron-deficiency anemia is a global health problem for mothers. While public health programs have aimed to correct iron deficiency in reproductive-aged women with supplementation, a small group of studies have shown that too much iron also has negative effects on birth outcomes. We hypothesize that women's iron levels evolved within a narrow optimum, and predict that hemoglobin (Hb) levels would be associated with women's fecundity. METHODOLOGY: We used the publicly available, longitudinal Tsimane' Amazonian Panel Study to test the association between -Hb levels and hazard of having a next birth (a measure of fecundity) among 116 parous, reproductive-aged Tsimane' women of Bolivia. A Cox proportional hazards model was used to model Hb level and other predictors against the event of next birth across the observation period, which began at each woman's previous birth. RESULTS: The higher the Hb level, the lower the hazard of a woman giving birth within the study observation period (hazard ratio=0.82, P = 0.03). However, there was no evidence that low Hb reduced women's fecundity. CONCLUSIONS AND IMPLICATIONS: These results demonstrate that high Hb influences women's fecundity. These results supports the growing body of literature showing that iron metabolism is critical for understanding the evolution of women's reproduction. More work is needed to determine the evolved optimal range of iron levels for reproductive-aged women. LAY SUMMARY: Lower chance of pregnancy among Tsimane' women with high Hb levels, suggesting evolved optimal Hb levels in women.

Perceptions and Practices of Infant Feeding among African American Women.

A large urban hospital in Florida implemented changes to achieve the Baby-Friendly Hospital Initiative (BFHI) designation in 2015 resulting in an increase of exclusive breastfeeding rates at hospital discharge; however, African American women continue to have the lowest rates overall. Qualitative interviews were conducted with 20 African American women who received prenatal care at a low-income women's clinic and gave birth at an affiliated BFHI hospital. Using a medical anthropology analytical framework to examine predisposing, enabling, and service-related factors that affect breastfeeding, this study investigated interpersonal, sociocultural, and institutional barriers to breastfeeding. Common challenges experienced by participants included lack of maternity leave from work, lack of access to electric pumps, social pressures to initiate formula supplementation, fears that breastfeeding renders infants overly dependent on their mother's care, and a lack of breastfeeding role models and/or support networks to normalize longer-term breastfeeding. We conclude that efforts to increase breastfeeding rates for African American women and promote culturally sensitive interventions must address underlying socioeconomic and structural barriers, women's perceptions of breastfeeding benefits and difficulties, and the need for improvements in postnatal lactation and doula support to foster a more inclusive culture of breastfeeding.

Ecological immunity of human milk: Life history perspectives from the United States and Kenya.

OBJECTIVES: Previous research has established population variation in anti-inflammatory immunological biomarkers in human milk. This immunity is potentially ecology-dependent and may alter the life history trade-off between growth and maintenance in infants. The current study has two aims: (1) to assess the ecological differences in milk immunity in two populations, one from the urban U.S. and one from rural Kenya; and (2) to test the hypothesis that milk immunity can affect infant growth indicators. MATERIALS AND METHODS: Kenyan Ariaal (n = 233) and U.S. (n = 75) breastfeeding mother-infant pairs participated in a cross-sectional study at two separate field sites. Laboratory analysis was performed on milk for the anti-inflammatory biomarkers TGF-ß2, sTNF-αRI, sTNF-αRII, and IL-1ra using ELISA. Multiple imputation was used to extrapolate data below the limit of detection before multivariate analysis. RESULTS: There were significant differences between U.S. and Kenyan mothers on all four milk biomarkers, with Kenyan mothers having significantly higher sTNF-αRI and sTNF-αRII and lower TGF-ß2 and IL-1ra than U.S. mothers. U.S. mothers with higher milk TGF-ß2 and IL-1ra have infants that are significantly longer and heavier for their age, while Kenyan mothers with higher sTNF-αRI have significantly longer and heavier infants for their age, and those with higher TGF-ß2 have marginally significantly longer infants. DISCUSSION: There were significant differences in ecological milk immunity between U.S. and Kenyan mothers. These differences potentially play a role in the growth of their infants. Further research in milk immunity should consider the possibility of shared maternal-infant life histories.