Associations between human breast milk hormones and adipocytokines and infant growth and body composition in the first 6 months of life

Human cytomegalovirus in breast milk is associated with milk composition and the infant gut microbiome and growth

Human cytomegalovirus (CMV) is a highly prevalent herpesvirus that is often transmitted to the neonate via breast milk. Postnatal CMV transmission can have negative health consequences for preterm and immunocompromised infants, but any effects on healthy term infants are thought to be benign. Furthermore, the impact of CMV on the composition of the hundreds of bioactive factors in human milk has not been tested. Here, we utilize a cohort of exclusively breastfeeding full-term mother-infant pairs to test for differences in the milk transcriptome and metabolome associated with CMV, and the impact of CMV in breast milk on the infant gut microbiome and infant growth. We find upregulation of the indoleamine 2,3-dioxygenase (IDO) tryptophan-to-kynurenine metabolic pathway in CMV+ milk samples, and that CMV+ milk is associated with decreased Bifidobacterium in the infant gut. Our data indicate two opposing CMV-associated effects on infant growth; with kynurenine positively correlated, and CMV viral load negatively correlated, with infant weight-for-length at 1 month of age. These results suggest CMV transmission, CMV-related changes in milk composition, or both may be modulators of full-term infant development.

Bioactive Components of Human Milk and Their Impact on Child's Health and Development, Literature Review

The composition of human breast milk is an ideal combination of substances necessary for the healthy development of an infant's body while protecting from pathogens and the balanced development of the microbiota. Its composition is dynamic and changes with the age of the child, meeting their current needs. The study provides a thorough overview of human milk components, such as immunological components, growth factors, hormones, carbohydrates, lipids, minerals, and vitamins. Authors focus on capturing the most important aspects of the effects of these substances on a newborn's body, while also looking for specific connections and describing the effects on given systems. Supplementation and the use of ingredients are also discussed. The purpose of this paper is to present the current state of knowledge about the bioactive components of human milk and their impact on the growth, development, and health of the young child.

Human Milk Composition Is Associated with Maternal Body Mass Index in a Cross-Sectional, Untargeted Metabolomics Analysis of Human Milk from Guatemalan Mothers

Background

Maternal overweight and obesity has been associated with poor lactation performance including delayed lactogenesis and reduced duration. However, the effect on human milk composition is less well understood.

Objectives

We evaluated the relationship of maternal BMI on the human milk metabolome among Guatemalan mothers.

Methods

We used data from 75 Guatemalan mothers who participated in the Household Air Pollution Intervention Network trial. Maternal BMI was measured between 9 and <20 weeks of gestation. Milk samples were collected at a single time point using aseptic collection from one breast at 6 mo postpartum and analyzed using high-resolution mass spectrometry. A cross-sectional untargeted high-resolution metabolomics analysis was performed by coupling hydrophilic interaction liquid chromatography (HILIC) and reverse phase C18 chromatography with mass spectrometry. Metabolic features associated with maternal BMI were determined by a metabolome-wide association study (MWAS), adjusting for baseline maternal age, education, and dietary diversity, and perturbations in metabolic pathways were identified by pathway enrichment analysis.

Results

The mean age of participants at baseline was 23.62 ± 3.81 y, and mean BMI was 24.27 ± 4.22 kg/m2. Of the total metabolic features detected by HILIC column (19,199 features) and by C18 column (11,594 features), BMI was associated with 1026 HILIC and 500 C18 features. Enriched pathways represented amino acid metabolism, galactose metabolism, and xenobiotic metabolic metabolism. However, no significant features were identified after adjusting for multiple comparisons using the Benjamini-Hochberg false discovery rate procedure (FDRBH < 0.2).

Conclusions

Findings from this untargeted MWAS indicate that maternal BMI is associated with metabolic perturbations of galactose metabolism, xenobiotic metabolism, and xenobiotic metabolism by cytochrome p450 and biosynthesis of amino acid pathways. Significant metabolic pathway alterations detected in human milk were associated with energy metabolism-related pathways including carbohydrate and amino acid metabolism.This trial was registered at clinicaltrials.gov as NCT02944682.

Understanding risk and causal mechanisms for developing obesity in infants and young children: A National Institutes of Health workshop

Obesity in children remains a major public health problem, with the current prevalence in youth ages 2-19 years estimated to be 19.7%. Despite progress in identifying risk factors, current models do not accurately predict development of obesity in early childhood. There is also substantial individual variability in response to a given intervention that is not well understood. On April 29-30, 2021, the National Institutes of Health convened a virtual workshop on "Understanding Risk and Causal Mechanisms for Developing Obesity in Infants and Young Children." The workshop brought together scientists from diverse disciplines to discuss (1) what is known regarding epidemiology and underlying biological and behavioral mechanisms for rapid weight gain and development of obesity and (2) what new approaches can improve risk prediction and gain novel insights into causes of obesity in early life. Participants identified gaps and opportunities for future research to advance understanding of risk and underlying mechanisms for development of obesity in early life. It was emphasized that future studies will require multi-disciplinary efforts across basic, behavioral, and clinical sciences. An exposome framework is needed to elucidate how behavioral, biological, and environmental risk factors interact. Use of novel statistical methods may provide greater insights into causal mechanisms.

Consistency and Variability of the Human Milk Oligosaccharide Profile in Repeat Pregnancies

Human milk oligosaccharides (HMOs) are a set of complex carbohydrates and the third largest solid component of human milk, after lactose and lipids. To date, over 150 HMOs have been identified and the diversity of structures produced by lactating women is influenced by maternal genetics as well as other maternal, infant, and environmental factors. While the concentrations of individual HMOs have been shown to vary between individuals and throughout the course of lactation, the variability of HMO concentration profiles following different pregnancies occurring in the same woman is presently unknown. As such, the objective of this study was to compare HMO concentrations in human milk samples provided by the same women (n = 34) following repeat pregnancies. We leveraged existing human milk samples and metadata from the UC San Diego Human Milk Research Biorepository (HMB) and measured the concentrations of the 19 most abundant HMOs using high-performance liquid chromatography with fluorescence detection (HPLC-FL). By assessing dissimilarities in HMO concentration profiles, as well as concentration trends in individual structures between pregnancies of each participant, we discovered that HMO profiles largely follow a highly personalized and predictable trajectory following different pregnancies irrespective of non-genetic influences. In conclusion, this is the first study to assess the interactions between parity and time following delivery on variations in HMO compositions.

Exercised breastmilk: a kick-start to prevent childhood obesity?

Exercise has systemic health benefits through effects on multiple tissues, with intertissue communication. Recent studies indicate that exercise may improve breastmilk composition and thereby reduce the intergenerational transmission of obesity. Even if breastmilk is considered optimal infant nutrition, there is evidence for variations in its composition between mothers who are normal weight, those with obesity, and those who are physically active. Nutrition early in life is important for later-life susceptibility to obesity and other metabolic diseases, and maternal exercise may provide protection against the development of metabolic disease. Here we summarize recent research on the influence of maternal obesity on breastmilk composition and discuss the potential role of exercise-induced adaptations to breastmilk as a kick-start to prevent childhood obesity.

Human Milk Bioactive Components and Child Growth and Body Composition in the First 2 Years: A Systematic Review

Human milk (HM) contains macronutrients, micronutrients, and a multitude of other bioactive factors, which can have a long-term impact on infant growth and development. We systematically searched MEDLINE, EMBASE, Cochrane Library, Scopus, and Web of Science to synthesize evidence published between 1980 and 2022 on HM components and anthropometry through 2 y of age among term-born infants. From 9992 abstracts screened, 141 articles were included and categorized based on their reporting of HM micronutrients, macronutrients, or bioactive components. Bioactives including hormones, HM oligosaccharides (HMOs), and immunomodulatory components are reported here, based on 75 articles from 69 unique studies reporting observations from 9980 dyads. Research designs, milk collection strategies, sampling times, geographic and socioeconomic settings, reporting practices, and outcomes varied considerably. Meta-analyses were not possible because data collection times and reporting were inconsistent among the studies included. Few measured infant HM intake, adjusted for confounders, precisely captured breastfeeding exclusivity, or adequately described HM collection protocols. Only 5 studies (6%) had high overall quality scores. Hormones were the most extensively examined bioactive with 46 articles (n = 6773 dyads), compared with 13 (n = 2640 dyads) for HMOs and 12 (n = 1422 dyads) for immunomodulatory components. Two studies conducted untargeted metabolomics. Leptin and adiponectin demonstrated inverse associations with infant growth, although several studies found no associations. No consistent associations were found between individual HMOs and infant growth outcomes. Among immunomodulatory components in HM, IL-6 demonstrated inverse relationships with infant growth. Current research on HM bioactives is largely inconclusive and is insufficient to address the complex composition of HM. Future research should ideally capture HM intake, use biologically relevant anthropometrics, and integrate components across categories, embracing a systems biology approach to better understand how HM components work independently and synergistically to influence infant growth.

Understanding the Immunological Quality of Breast Milk in Maternal Overweight and Obesity

Maternal obesity, affecting many pregnant women globally, not only poses immediate health risks but also modulates breast milk composition. Obesity is linked to inflammation and oxidative stress, impacting breast milk's immune properties. This paper explores the intricate relationship between maternal metabolic disorders, such as obesity, and breast milk's immunological components. We conducted a thorough search for original and review articles published until 17 October 2023 in the PUBMED/Scopus database. This search included several terms related to human breast milk, immunological properties, and obesity. Articles were selected with the consensus of all authors. Maternal metabolic disorders have discernible effects on the composition of immune-related components in breast milk, such as immunoglobulins, lactoferrin, leptin, ghrelin, adiponectin, C-reactive protein, growth factors, extracellular vesicles, and lymphocytes. These changes in breast milk composition can significantly impact the newborn's immune system, with potential long-term health implications beyond the immediate postnatal period. Maternal metabolic health is a critical factor in shaping the health trajectory of the neonate through breastfeeding, although the full advantages of breastfeeding for children of mothers with obesity remain uncertain. Ongoing research aims to understand and unravel these links.

Preterm Delivery in Obese Mothers Predicts Tumor Necrosis Factor-α Levels in Breast Milk

Background: Breast milk (BM) is a nutritive fluid that is rich in bioactive components such as hormones and cytokines that can shape the newborn's feeding habits and program the newborn's immature immune system. BM components can change under different scenarios that include maternal body mass index (BMI) and premature birth. This study aimed to study the interaction of premature status or maternal obesity on the hormonal and cytokine profile in BM according to the sex of the offspring. Materials and Methods: We recruited 31 women with preterm births from the Centro de Alta Especialidad Dr. Rafael Lucio in Mexico. Luminex multiplexing assay was used for quantifying cytokine profile of monocyte chemoattractant protein-1, tumor necrosis factor (TNF)-α, interferon-γ, interleukin (IL)1-β, IL-2, IL-4, IL-6, IL-7, and hormones insulin, ghrelin, leptin, and glucagon in mature BM samples. Biological modeling was performed to predict the interaction between cytokines and hormones, maternal BMI status, infant birth sex, parity, and gestational age. Results: BM multiplex analysis showed positive correlations for TNF-α and increasing prematurity and for higher maternal BMI and IL-2, IL-4, and IL-6 cytokines. Multiple regression models identified an interaction between maternal BMI and gestational weeks in male infants that is associated to TNF-α accumulation in BM. Biological modeling predicts that preterm delivery in mothers with obesity modulates TNF- α levels in mature BM of women with male offspring. Conclusion: Prematurity and obesity modify BM's immune profile. TNF- α expression increases as prematurity increases, and maternal BMI correlates positively with increases in IL-2, IL-6, and IL-4. Our multiple regression model also shows that maternal BMI and gestational weeks in male infants predict TNF-α.

Human Milk Nutrient Composition Data is Critically Lacking in the United States and Canada: Results from a Systematic Scoping Review of 2017-2022

Characterization of the nutrients in human milk is important to understand the dietary and developmental requirements of infants. The objective of this review was to summarize the state-of-the-science on the nutrient composition of human milk in the United States and Canada published from 2017 to 2022. Four databases were searched for randomized controlled studies and others given the scoping nature of this review. We limited type to mature milk collected 21 d postpartum and beyond from lactating individuals in the United States and Canada who gave birth at 37-wk gestation or later (full-term). Outcomes of interest included traditional macro- and micronutrients, including human milk oligosaccharides (HMOs), and milk volume. The publication date range was selected as January 1, 2017, to the day the literature search was performed. A total of 32 articles were included in the scoping review from primarily longitudinal cohort or cross-sectional designs. The most prevalent sample collection method was full-breast expression (n = 20) with most studies (n = 26) collecting samples from a single timepoint. Carbohydrates (HMOs [n = 12], glucose [n = 8], and lactose [n = 6]) and protein (n = 5) were the most frequently assessed nutrients in this body of work, with consensus among studies that glucose is present in limited concentrations compared to lactose (24-64 mg/dL compared with 6-7 g/dL) and that HMOs are influenced by temporality and secretor status. Included studies displayed an overall level of heterogeneity and sparsity paralleling previous reports and nutrient data in the USDA FoodData Central system. Much of the data extracted from retained articles generally provided analysis of a specific nutrient or group of nutrients. Moreover, many studies did not use the preferred analytical methods as outlined by the Human Milk Composition Initiative to increase measurement confidence. Up-to-date nutrient composition data of human milk is still greatly needed as it is paramount for the management of infant feeding, assessment of infant and maternal nutritional and health needs, and as a reference for infant formula development.

Breast milk leptin concentrations and infant anthropometric indicators in SGA versus non-SGA breastfed infants born at term

Leptin concentrations in breast milk can influence metabolic programming during the first months of life. Small for gestational age (SGA) newborns show a peculiar growth pattern after birth, which can lead to adulthood diseases. This study aims to assess an association between leptin concentration in mature breast milk and the infant anthropometric indicators of the SGA and the non-SGA groups, in addition, to comparing the hormone level between these groups. A longitudinal study was performed with mother-infant pairs. The maternal sociodemographic information was collected in the first 48 h postpartum. Breast milk was collected at one month postpartum and leptin concentrations were obtained by immunoassays. The infant anthropometric measurements were collected at three and six months postpartum and included weight, height (to body mass index-BMI calculated), triceps skinfold (TSF), and subscapular skinfold (SSF). The BMI for age (BMI/A), TSF, and SSF were calculated by Z-score indicators. Data from 67 mother-infant pairs (n = 16 SGA and n = 51 non-SGA) were analyzed. In univariate analyses, the breast milk of the SGA group had lower leptin concentrations than the non-SGA group (p = 0.006), however, after adjustment, there was no difference between groups (p = 0.181). In the SGA group, there was a significant association between leptin concentrations and lower SSF at six months in infants, after adjustment (p = 0.003). In the non-SGA group, the breast milk leptin was associated with lower BMI/A at three and six months in infants, after adjustment (p = 0.002 and p = 0.010, respectively). The association between breast milk leptin concentrations with SSF in the SGA group and BMI/A in the non-SGA group suggests that leptin may be a modulating factor in infant growth in the first months of life.

Relationships between the Intakes of Human Milk Components and Body Composition of Breastfed Infants: A Systematic Review

Human milk provides all of the elements necessary for infant growth and development. Previous studies have reported associations between breastfeeding and a reduced risk of developing obesity and late-onset metabolic disorders; however, the underlying mechanisms are poorly understood. Recently, intakes of human milk components have been associated with infant body composition, which is likely partially implicated in the reduced risk of developing childhood obesity among breastfed infants. In this systematic review, we searched electronic bibliographic databases for studies that explored relationships between the 24 h intakes of human milk macronutrients and bioactive components and infant body composition and/or growth parameters. Of 13 eligible studies, 10 assessed relationships of infant body composition and growth outcomes with human milk macronutrients, while 8 studies assessed relationships with human milk bioactive components. Significant time-dependent relationships with infant anthropometrics and body composition were found for intakes and no relationships for concentrations of several human milk components, such as lactose, total protein, and human milk oligosaccharides, suggesting that measuring concentrations of human milk components without quantifying the intake by the infant may provide a limited understanding. Future studies investigating the effect of human milk components on infant growth and body composition outcomes should consider measuring the actual intake of components and employ standardised methods for measuring milk intake.

A longitudinal study of fatty acid profiles, macronutrient levels, and plasmin activity in human milk

Introduction

Human milk provides nutrients essential for infant growth and health, levels of which are dynamic during lactation.

Methods

In this study, changes in macronutrients, fatty acids, and plasmin activities over the first six months of lactation in term milk were studied.

Results

There was a significant influence of lactation stage on levels of protein and plasmin activities, but not on levels of fat and carbohydrate in term milk. Concerning fatty acids in term milk, levels of caproic acid and α-linolenic acid increased significantly (p < 0.05), whereas those of arachidonic acid and docosahexaenoic acid decreased, in the six months after birth. Significant impacts of maternal pre-pregnancy BMI and infant gender on fatty acid profiles were also found. Multivariate statistical analysis showed that protein level, plasmin activity, and several fatty acids (α-linolenic acid, lignoceric acid, and docasadienoic acid) contributed strongly to discrimination of milk from different lactational stages.

Discussion

The study demonstrates that not all but some fatty acids were influenced by lactation, whereas protein and protease levels showed clear decreasing trends during lactation, which may help in understanding the nutritional requirements of infants.

The Impact of the Human Milk Microbiota in the Prevention of Disease and Infant Health

Background: Human milk is recognized as an ideal food for newborns and infants owing to the presence of various nutritive factors, including healthy bacteria. Aim/Objective: This review aimed to understand the effects of human milk microbiota in both the prevention of disease and the health of infants. Methods: Data were obtained from PubMed, Scopus, Web of Science, clinical trial registries, Dergipark, and Türk Atıf Dizini up to February 2023 without language restrictions. Results: It is considered that the first human milk microbiota ingested by the newborn creates the initial microbiome of the gut system, which in turn influences the development and maturation of immunity. Bacteria present in human milk modulate the anti-inflammatory response by releasing certain cytokines, protecting the newborn against certain infections. Therefore, certain bacterial strains isolated from human milk could serve as potential probiotics for various therapeutic applications. Conclusions: In this review, the origin and significance of human milk bacteria have been highlighted along with certain factors influencing the composition of human milk microbiota. In addition, it also summarizes the health benefits of human milk as a protective agent against certain diseases and ailments.

Hormonal regulation of mammary gland development and lactation

Lactation is critical to infant short-term and long-term health and protects mothers from breast cancer, ovarian cancer and type 2 diabetes mellitus. The mammary gland is a dynamic organ, regulated by the coordinated actions of reproductive and metabolic hormones. These hormones promote gland development from puberty onwards and induce the formation of a branched, epithelial, milk-secreting organ by the end of pregnancy. Progesterone withdrawal following placental delivery initiates lactation, which is maintained by increased pituitary secretion of prolactin and oxytocin, and stimulated by infant suckling. After weaning, local cytokine production and decreased prolactin secretion trigger large-scale mammary cell loss, leading to gland involution. Here, we review advances in the molecular endocrinology of mammary gland development and milk synthesis. We discuss the hormonal functions of the mammary gland, including parathyroid hormone-related peptide secretion that stimulates maternal calcium mobilization for milk synthesis. We also consider the hormonal composition of human milk and its associated effects on infant health and development. Finally, we highlight endocrine and metabolic diseases that cause lactation insufficiency, for example, monogenic disorders of prolactin and prolactin receptor mutations, maternal obesity and diabetes mellitus, interventions during labour and delivery, and exposure to endocrine-disrupting chemicals such as polyfluoroalkyl substances in consumer products and other oestrogenic compounds.

The associations of maternal and paternal obesity with latent patterns of offspring BMI development between 7 and 17 years of age: pooled analyses of cohorts born in 1958 and 2001 in the United Kingdom

OBJECTIVE

We aimed to 1) describe how the UK obesity epidemic reflects a change over time in the proportion of the population demonstrating adverse latent patterns of BMI development and 2) investigate the potential roles of maternal and paternal BMI in this secular process.

METHODS

We used serial BMI data between 7 and 17 years of age from 13220 boys and 12711 girls. Half the sample was born in 1958 and half in 2001. Sex-specific growth mixture models were developed. The relationships of maternal and paternal BMI and weight status with class membership were estimated using the 3-step BCH approach, with covariate adjustment.

RESULTS

The selected models had five classes. For each sex, in addition to the two largest normal weight classes, there were "normal weight increasing to overweight" (17% of boys and 20% of girls), "overweight increasing to obesity" (8% and 6%), and "overweight decreasing to normal weight" (3% and 6%) classes. More than 1-in-10 children from the 2001 birth cohort were in the "overweight increasing to obesity" class, compared to less than 1-in-30 from the 1958 birth cohort. Approximately 75% of the mothers and fathers of this class had overweight or obesity. When considered together, both maternal and paternal BMI were associated with latent class membership, with evidence of negative departure from additivity (i.e., the combined effect of maternal and paternal BMI was smaller than the sum of the individual effects). The odds of a girl belonging to the "overweight increasing to obesity" class (compared to the largest normal weight class) was 13.11 (8.74, 19.66) times higher if both parents had overweight or obesity (compared to both parents having normal weight); the equivalent estimate for boys was 9.01 (6.37, 12.75).

CONCLUSIONS

The increase in obesity rates in the UK over more than 40 years has been partly driven by the growth of a sub-population demonstrating excess BMI gain during adolescence. Our results implicate both maternal and paternal BMI as correlates of this secular process.

Postnatal Leptin Levels Correlate with Breast Milk Leptin Content in Infants Born before 32 Weeks Gestation

Perinatal leptin deficiency and reduced intake of mother’s milk may contribute to the development of childhood obesity. Preterm infants have reduced leptin production, and they are at heightened risk of neonatal leptin deficiency. Because fresh human milk contains significantly more leptin than donor milk, we used a cross-over design to determine if blood leptin levels in maternal milk-fed preterm infants fall during conversion to donor human milk. Infants born between 22 0/7 and 31 6/7 weeks gestation on exclusive maternal milk feedings were enrolled into a 21-day cross-over trial. On days 1−7 and 15−21, infants were fed maternal milk, and on days 8−14, infants were fed donor milk. On day 1, study infants had a mean postmenstrual age of 33 weeks. Plasma leptin correlated with milk leptin, and leptin levels in maternal milk far exceed the leptin levels of donor milk. Plasma leptin did not increase during donor milk administration, but it did following resumption of maternal milk (p < 0.05). In this crossover trial, preterm infant blood leptin levels correlated with milk leptin content. This suggests that preterm infants can enterally absorb leptin from human milk, and leptin-rich breast milk may be a targeted therapy for the prevention of obesity.

Associations between maternal adiposity and appetite-regulating hormones in human milk are mediated through maternal circulating concentrations and might affect infant outcomes

Background

Appetite-regulating hormones (ARH) in human milk (HM) are suggested to affect infants’ milk intake and possibly infant growth. Maternal adiposity might contribute to higher levels of ARH in HM, either from the mammary gland or from raised circulating levels due to higher adiposity. Counterfactual-based mediation analysis can define indirect and direct effects between HM ARH and maternal and infant factors, and might be an important tool when investigating the mother-milk-infant triad.

Objective

We aim to investigate whether potential associations between (1) maternal adiposity and HM ARH and (2) HM ARH and infant milk intake and growth are mediated through maternal and infant plasma ARH, respectively.

Materials and methods

Maternal and infant anthropometry and body composition, HM and blood samples were collected from 223 mother-infant dyads participating in the Mother, Infant and Lactation Quality study at three postpartum visits from 1 to 8.49 months. Leptin, insulin and adiponectin were analyzed using immunoassays. Mediation analyses using linear mixed-effect models were applied to investigate the direct and indirect effects through maternal and infant plasma hormone concentrations.

Results

A positive association between maternal body-mass-index (BMI) and HM leptin was mediated by maternal plasma leptin by 29% when fixing BMI to < 25 kg/m², and through 51% when fixing BMI to ≥ 25 kg/m² (p_interaction < 0.01). There was no mediated effect through plasma insulin in the association between BMI and HM insulin (p = 0.068). We found negative and positive associations between HM insulin and total milk intake and infant weight, respectively, however, these diminished in mediation analyses with reduced sample sizes.

Conclusion

Our main results suggest that the association between maternal adiposity and HM leptin was mediated through circulating leptin to a stronger degree for mothers with overweight compared to mothers with normal-weight. This indicates that excess maternal adiposity, and the resulting rise of circulating leptin and possible concomitant low-grade inflammation, may be reflected in HM composition.

Clinical trials registry number

NCT03254329.

Early Growth and Cognitive Development in Children Born Preterm: Relevance of Maternal Body Mass Index

OBJECTIVE

Maternal prepregnancy body mass index (BMI) represents a surrogate marker of fetal exposures to the maternal metabolism during pregnancy. Yet, it remains poorly understood whether this marker indicates risk of altered trajectories in postnatal growth and development in children born preterm. This study aimed to determine whether maternal prepregnancy BMI is associated with altered growth and development in children born preterm.

STUDY DESIGN

A retrospective cohort study evaluated prepregnancy BMI as the exposure for childhood outcomes using linear regression and mixed effects models. The 38 children included in this follow-up evaluation originally participated in a prospective, observational cohort study to determine longitudinal levels of lipid species in preterm human milk expressed by women who delivered prior to 32 weeks. Childhood outcomes in this study were anthropometric measures during hospitalization (n = 38), after discharge through 36 months (n = 34) and Bayley-III developmental scores through 18 months corrected age (n = 26).

RESULTS

In 38 children born prior to 32 weeks, higher maternal prepregnancy BMI was independently associated with higher preterm infant growth velocity during hospitalization, but not associated with in-hospital change in length or head circumference and/or postdischarge growth. In univariate linear regression models, higher maternal BMI was associated with lower cognitive scores at 18 months corrected age. This significant association remained in an adjusted model accounting for relevant influences on early childhood development.

CONCLUSION

Increasing maternal prepregnancy BMI may reflect risk of altered growth and cognitive development in children born preterm.

KEY POINTS

· Maternal BMI was associated with early preterm infant weight gain.. · Maternal BMI was not associated with postdischarge growth.. · Increased maternal BMI may be associated with lower cognitive function scores in offspring..

Factors influencing development of the infant microbiota: from prenatal period to early infancy

During early life, the gut microbial composition rapidly changes by maternal microbiota composition, delivery mode, infant feeding mode, antibiotic usage, and various environmental factors, such as the presence of pets and siblings. An integrative study on the diet, the microbiota, and genomic activity at the transcriptomic level may give an insight into the role of diet in shaping the human/microbiome relationship. Disruption in the gut microbiota (i.e., gut dysbiosis) has been linked to necrotizing enterocolitis in infancy, as well as some chronic diseases in later, including obesity, diabetes, inflammatory bowel disease, cancer, allergies, and asthma. Therefore, understanding the impact of maternal-to-infant transfer of dysbiotic microbes and then modifying infant early colonization or correcting early-life gut dysbiosis might be a potential strategy to overcome chronic health conditions.

Breastfeeding duration modifies the association between maternal weight status and offspring dietary palmitate oxidation

BACKGROUND

Offspring of obese rodents develop a metabolic phenotype that favors fat deposition. Data regarding the impact of maternal obesity programing of offspring fuel usage in humans is scarce.

OBJECTIVE

The objective of this study was to explore the association between maternal weight status and dietary palmitate oxidation (DPO) in 2-y-old offspring, taking into consideration potential confounders and modifiers.

METHODS

Women (n = 56) were enrolled by the first trimester of gestation. Maternal physical activity (PA; measured with accelerometers) at enrollment and gestational weight gain (GWG) were measured. Offspring sex, race, and breastfeeding (BF) duration were self-reported. Human milk (HM) composition was determined at 6 mo postpartum. At age 2 y, dietary quality [healthy eating index (HEI)] and parental feeding practices [Child Feeding Questionnaire (CFQ)] were assessed. DPO in 2-y-olds (2-yo-DPO) was measured using deuterated palmitic acid. Generalized linear regression analysis was used to model the associations of 2-yo-DPO with maternal weight status [normal weight (NW), BMI <25 (in kg/m2) compared with excessive weight (EW), BMI ≥25].

RESULTS

DPO was higher in offspring of women with EW compared with NW (2.1 ± 1.2%/h compared with 1.4 ± 0.7%/h, P = 0.03). Maternal weight status interacted with BF duration in association with 2-yo-DPO (log ß: 0.05, P = 0.04). Specifically, 2-yo-DPO was higher in the EW compared with NW group if BF duration was ≥9 mo. HM insulin (log ß: 0.35, P = 0.002) and HM leptin (log ß: 0.81, P = 0.001) concentrations directly associated with 2-yo-DPO. PA (log ß: 0.06, P = 0.013), parental feeding restriction (log ß: 0.05, P < 0.0001), and male sex (log ß: 0.54, P < 0.001) were positively associated with 2-yo-DPO. HEI was negatively associated with 2-yo-DPO (log ß:-0.03, P < 0.0001).

CONCLUSIONS

Higher 2-yo-DPO in offspring of women with EW compared with NW were driven by BF duration. Higher HM insulin and leptin concentrations in women with EW may explain these finding. More studies are needed to confirm these results. This trial was registered at clinicaltrials.gov as NCT03281850.

Iron mobilization during lactation reduces oxygen stores in a diving mammal

The profound impacts that maternal provisioning of finite energy resources has on offspring survival have been extensively studied across mammals. This study shows that in addition to calories, high hemoprotein concentrations in diving mammals necessitates exceptional female-to-pup iron transfer. Numerous indices of iron mobilization (ferritin, serum iron, total-iron-binding-capacity, transferrin saturation) were significantly elevated during lactation in adult female Weddell seals (Leptonychotes weddellii), but not in skip-breeders. Iron was mobilized from endogenous stores for incorporation into the Weddell seal’s milk at concentrations up to 100× higher than terrestrial mammals. Such high rates of iron offload to offspring drew from the female’s own heme stores and led to compromised physiologic dive capacities (hemoglobin, myoglobin, and total body oxygen stores) after weaning their pups, which was further reflected in shorter dive durations. We demonstrate that lactational iron transfer shapes physiologic dive thresholds, identifying a cost of reproduction to a marine mammal.

Here, the authors show that Weddell seal mothers mobilize endogenous iron stores during lactation to provide to pups, resulting in iron concentrations in milk 100x higher than terrestrial mammals. This was associated with reduced dive durations in the mother, a cost of reproduction.

Breastfeeding may benefit cardiometabolic health of children exposed to increased gestational glycemia in utero

PURPOSE

There is altered breastmilk composition among mothers with gestational diabetes and conflicting evidence on whether breastfeeding is beneficial or detrimental to their offspring's cardiometabolic health. We aimed to investigate associations between breastfeeding and offspring's cardiometabolic health across the range of gestational glycemia.

METHODS

We included 827 naturally conceived, term singletons from a prospective mother-child cohort. We measured gestational (26-28 weeks) fasting plasma glucose (FPG) and 2-h plasma glucose (2 hPG) after an oral glucose tolerance test as continuous variables. Participants were classified into 2 breastfeeding categories (high/intermediate vs. low) according to their breastfeeding duration and exclusivity. Main outcome measures included magnetic resonance imaging (MRI)-measured abdominal fat, intramyocellular lipids (IMCL), and liver fat, quantitative magnetic resonance (QMR)-measured body fat mass, blood pressure, blood lipids, and insulin resistance at 6 years old (all continuous variables). We evaluated if gestational glycemia (FPG and 2 hPG) modified the association of breastfeeding with offspring outcomes after adjusting for confounders using a multiple linear regression model that included a 'gestational glycemia × breastfeeding' interaction term.

RESULTS

With increasing gestational FPG, high/intermediate (vs. low) breastfeeding was associated with lower levels of IMCL (p-interaction = 0.047), liver fat (p-interaction = 0.033), and triglycerides (p-interaction = 0.007), after adjusting for confounders. Specifically, at 2 standard deviations above the mean gestational FPG level, high/intermediate (vs. low) breastfeeding was linked to lower adjusted mean IMCL [0.39% of water signal (0.29, 0.50) vs. 0.54% of water signal (0.46, 0.62)], liver fat [0.39% by weight (0.20, 0.58) vs. 0.72% by weight (0.59, 0.85)], and triglycerides [0.62 mmol/L (0.51, 0.72) vs. 0.86 mmol/L (0.75, 0.97)]. 2 hPG did not significantly modify the association between breastfeeding and childhood cardiometabolic risk.

CONCLUSION

Our findings suggest breastfeeding may confer protection against adverse fat partitioning and higher triglyceride concentration among children exposed to increased glycemia in utero.

Human Milk Extracellular Vesicles: A Biological System with Clinical Implications

The consumption of human milk by a breastfeeding infant is associated with positive health outcomes, including lower risk of diarrheal disease, respiratory disease, otitis media, and in later life, less risk of chronic disease. These benefits may be mediated by antibodies, glycoproteins, glycolipids, oligosaccharides, and leukocytes. More recently, human milk extracellular vesicles (hMEVs) have been identified. HMEVs contain functional cargos, i.e., miRNAs and proteins, that may transmit information from the mother to promote infant growth and development. Maternal health conditions can influence hMEV composition. This review summarizes hMEV biogenesis and functional contents, reviews the functional evidence of hMEVs in the maternal–infant health relationship, and discusses challenges and opportunities in hMEV research.

Influence of Neonatal Sex on Breast Milk Protein and Antioxidant Content in Spanish Women in the First Month of Lactation

Breast milk (BM) is the best food for newborns. Male sex is associated with a higher risk of fetal programming, prematurity, and adverse postnatal outcome, being that BM is an important health determinant. BM composition is dynamic and modified by several factors, including lactation period, prematurity, maternal nutritional status, and others. This study was designed to evaluate the influence of sex on BM composition during the first month of lactation, focused on macronutrients and antioxidants. Forty-eight breastfeeding women and their fifty-five newborns were recruited at the Hospital Clínico San Carlos (Madrid, Spain). Clinical sociodemographic data and anthropometric parameters were collected. BM samples were obtained at days 7, 14, and 28 of lactation to assess fat (Mojonnier method), protein (Bradford method), and biomarkers of oxidative status: total antioxidant capacity (ABTS and FRAP methods), thiol groups, reduced glutathione, superoxide dismutase and catalase activities, lipid peroxidation, and protein oxidation (spectrophotometric methods). Linear mixed models with random effects adjusted by maternal anthropometry, neonatal Z-scores at birth, and gestational age were used to assess the main effects of sex, lactation period, and their interaction. BM from mothers with male neonates exhibited significantly higher protein, ABTS, FRAP, and GSH levels, while catalase showed the opposite trend. No differences between sexes were observed in SOD, total thiols, and oxidative damage biomarkers. Most changes were observed on day 7 of lactation. Adjusted models demonstrated a significant association between male sex and proteins (β = 2.70 ± 1.20; p-Value = 0.048). In addition, total antioxidant capacity by ABTS (β = 0.11 ± 0.06) and GSH (β = 1.82 ± 0.94) showed a positive trend near significance (p-Value = 0.056; p-Value = 0.064, respectively). In conclusion, transitional milk showed sex differences in composition with higher protein and GSH levels in males. This may represent an advantage in the immediate perinatal period, which may help to counteract the worse adaptation of males to adverse intrauterine environments and prematurity.

Implementation of a healthy diet to lactating rats attenuates the early detrimental programming effects in the offspring born to obese dams. Putative relationship with milk hormone levels

Lactation is a critical period of development and alterations in milk composition due to maternal diet or status may affect infant growth. We aimed to evaluate in rats whether improving maternal nutrition during lactation attenuates early imprinted adverse metabolic effects in the offspring born to obese dams. Three groups were studied: Control (C) dams, fed with standard diet; Western diet (WD) dams, fed with WD one month prior to gestation and during gestation and lactation; and Reversion (Rev) dams, fed as WD-dams, but moved to a standard diet during lactation. Macronutrient content, insulin, leptin and adiponectin levels were determined in milk. Phenotypic traits and circulating parameters in dams and their offspring were determined throughout lactation. Results showed that, at weaning, WD-dams displayed lower body weight and greater plasma insulin and non-esterified fatty acids levels than C-dams, and signs of hepatic steatosis. Milk from WD-dams showed lower protein content and insulin, leptin, and adiponectin levels during the entire or the late lactation. Rev-dams retained excess body fat content, but milk composition and most circulating parameters were not different from controls at late lactation and showed higher leptin mRNA levels in mammary gland than WD-dams. The offspring of WD-dams, but not that of Rev-dams, displayed higher body weight, adiposity, and circulating leptin and glucose levels than controls at weaning. In conclusion, dietary improvement during lactation prevents early adverse effects in offspring associated with maternal intake of an obesogenic diet, that may be related with the normalization of milk hormone levels.

Human milk: From complex tailored nutrition to bioactive impact on child cognition and behavior

Human milk is a highly complex liquid food tailor-made to match an infant's needs. Beyond documented positive effects of breastfeeding on infant and maternal health, there is increasing evidence that milk constituents also impact child neurodevelopment. Non-nutrient milk bioactives would contribute to the (long-term) development of child cognition and behavior, a process termed 'Lactocrine Programming'. In this review we discuss the current state of the field on human milk composition and its links with child cognitive and behavioral development. To promote state-of-the-art methodologies and designs that facilitate data pooling and meta-analytic endeavors, we present detailed recommendations and best practices for future studies. Finally, we determine important scientific gaps that need to be filled to advance the field, and discuss innovative directions for future research. Unveiling the mechanisms underlying the links between human milk and child cognition and behavior will deepen our understanding of the broad functions of this complex liquid food, as well as provide necessary information for designing future interventions.

Century Wide Changes in Macronutrient Levels in Indian Mothers’ Milk: A Systematic Review

The purpose of this systematic review was to understand Indian mothers’ milk composition and report changes in it over the past 100 years. A review was conducted in accordance with PRISMA and registered with PROSPERO (CRD42022299224). All records published between 1921 and 2021 were identified by searching databases Google Scholar, ResearchGate, PubMed, and the Cochrane Database of Systematic Reviews. All observational, interventional, or supplementation studies reporting macronutrients (protein, fat, lactose) in milk of Indian mothers, delivering term infants, were included. Publications on micronutrients, preterm, and methods were excluded. Milk was categorized into colostrum, transitional, and mature. In all, 111 records were identified, of which 34 were included in the final review. Fat ranged from 1.83 to 4.49 g/100 mL, 2.6 to 5.59 g/100 mL, and 2.77 to 4.78 g/100 mL in colostrum, transitional, and mature milk, respectively. The protein was higher in colostrum (1.54 to 8.36 g/100mL) as compared to transitional (1.08 to 2.38 g/100 mL) and mature milk (0.87 to 2.33 g/100 mL). Lactose was lower in colostrum (4.5–6.47 g/100 mL) as compared to transitional (4.8–7.37 g/100 mL) and mature milk ranges (6.78–7.7 g/100 mL). The older studies (1950–1980) reported higher fat and protein in colostrum as compared to subsequent time points. There were variations in maternal nutritional status, diet, socioeconomic status, and regions along with study design specific differences of time or methods of milk sampling and analysis. Additionally, advancements in methods over time make it challenging to interpret time trends. The need for conducting well-designed, multicentric studies on nutrient composition of Indian mother’s milk using standardized methods of sampling and estimation for understanding the role of various associated factors cannot be undermined.

Infant sex differences in human milk intake and composition from 1- to 3-month post-delivery in a healthy United States cohort

BACKGROUND

Macronutrient composition of human milk differs by infant sex, but few studies have examined sex differences in other milk components, or their potential modification by maternal body mass index (BMI).

AIM

We compared milk intake and human milk hormone and cytokine concentrations at 1- and 3-month post-delivery and tested infant sex by maternal BMI (OW/OB vs. NW) interactions.

SUBJECTS AND METHOD

Data were analysed for 346 mother-infant dyads in the Mothers and Infants Linked for Healthy Growth (MILk) Study at 1- and 3-month post-delivery. Infant milk intake was estimated by the change in infant weight after test feedings. Concentrations of glucose, insulin, leptin, adiponectin, interleukin-6 (IL-6), and C-reactive protein (CRP) were measured using ELISA. Multivariable linear regression and linear mixed models were used to estimate sex main effects and their interaction with maternal BMI.

RESULTS

Mean glucose concentration at 1 month was 2.62 mg/dl higher for male infants, but no difference at 3 months was observed. Milk intake and concentrations for the other milk components were similar for males and females at both time points. Associations with infant sex did not differ significantly by maternal BMI.

CONCLUSIONS

Among healthy United States mother-infant dyads, appetite, and growth-regulating factors in human milk did not differ significantly by infant sex.

Gestational Diabetes Mellitus Is Associated with Altered Abundance of Exosomal MicroRNAs in Human Milk

PURPOSE

Human milk (HM) is a unique biological fluid that is enriched with a variety of factors, including microRNAs (miRNAs) that potentially provide both short- and long-term benefits to the infants. miRNAs are packaged within exosomes, making them bioavailable to infants. Gestational diabetes mellitus (GDM) may affect the abundance of exosomal miRNAs in HM, providing a mechanism for growth and adiposity variation in infants of mothers with GDM in early life. Therefore, the purposes of this study were to examine the impact of GDM on select miRNAs (miRNA-148a, miRNA-30b, miRNA-let-7a, and miRNA-let-7d) involved in metabolism and to examine the association of these miRNAs with measures of infant body composition in the first 6 months of life.

METHODS

Milk samples were collected from a cohort of 94 mothers (62 mothers without GDM and 32 mothers with GDM) matched on body mass index strata at 1 month post partum. miRNA abundance was measured by real-time polymerase chain reaction. Linear regression models were used to examine potential differences in miRNA abundance in women with and without GDM, testing associations between miRNA abundance and infant growth and body composition measures from 1 to 6 months.

FINDINGS

The abundances of miRNA-148a, miRNA-30b, miRNA-let-7a, and miRNA-let-7d were reduced in milk from mothers with GDM. Independent of GDM status, higher maternal diet quality was associated with increased abundance of each of the measured miRNAs. miRNA-148a was negatively associated with infant weight, percentage of body fat, and fat mass, whereas miRNA-30b was positively associated with infant weight and fat mass at 1 month of age. There was no association of milk miRNA-148a and miRNA-30b with infant weight at 1 month of age or with body composition measures at 3 months of age; however, miRNA-148a was negatively associated with infant weight at 6 months of age.

IMPLICATIONS

If supported by randomized dietary supplementation or other intervention trials, HM miRNAs may be a therapeutic target to mitigate risk of metabolic outcomes in offspring of women with GDM.

Human Milk Glucose, Leptin, and Insulin Predict Cessation of Full Breastfeeding and Initiation of Formula Use

Objective: We aimed to investigate prospective associations between milk bioactives related to metabolic health (glucose, insulin, leptin, C reactive protein [CRP], and interleukin 6 [IL-6]) and incident formula initiation at 3 and 6 months postpartum. Design: This study included 363 mother-infant dyads who were fully breastfed at 1 month and participated in the prospective Mothers and Infants Linked for Healthy Growth study from pregnancy to 6 months postpartum. Associations between milk glucose, leptin, insulin, CRP, and IL-6 at 1 and 3 months and incident formula feeding (FF) at 3 and 6 months, respectively, were tested using multiple logistic regression, adjusting for numerous potential confounders such as maternal age and prepregnancy body mass index. Results: At 3 months postpartum, 1-month glucose (odds ratio [OR] 0.45 [95% confidence interval (CI): 0.27-0.75], p ≤ 0.01) and smaller decreases in glucose from 1 to 3 months (OR 0.51 [95% CI: 0.28-0.92], p = 0.03) were associated with lower odds of FF, whereas 1-month leptin (OR 2.30 [95% CI: 1.30-4.07], p < 0.01) and larger increase in insulin (OR 1.86 [95% CI: 1.23-2.81], p < 0.01) and leptin (OR 2.17 [95% CI: 1.29-3.68], p < 0.01) from 1 to 3 months were associated with increased odds of FF. At 6 months, insulin increases (OR 2.08 [95% CI: 1.03-4.17], p = 0.04) were associated with higher odds of FF. Conclusions: In a cohort of women with established lactation, 1-month milk glucose, insulin, and leptin predicted initiation of FF at 3 months. Early milk composition may provide a window into mammary gland function, allowing identification of women at risk of not meeting their breastfeeding goals.

Can breastfeeding affect the rest of our life?

The breastfeeding period is one of the most important critical windows in our development, since milk, our first food after birth, contains several compounds, such as macronutrients, micronutrients, antibodies, growth factors and hormones that benefit human health. Indeed, nutritional, and environmental alterations during lactation, change the composition of breast milk and induce alterations in the child's development, such as obesity, leading to the metabolic dysfunctions, cardiovascular diseases and neurobehavioral disorders. This review is based on experimental animal models, most of them in rodents, and summarizes the impact of an adequate breast milk supply in view of the developmental origins of health and disease (DOHaD) concept, which has been proposed by researchers in the areas of epidemiology and basic science from around the world. Here, experimental advances in understanding the programming during breastfeeding were compiled with the purpose of generating knowledge about the genesis of chronic noncommunicable diseases and to guide the development of public policies to deal with and prevent the problems arising from this phenomenon. This review article is part of the special issue on "Cross talk between periphery and brain".

Associations Among Maternal Adiposity, Insulin, and Adipokines in Circulation and Human Milk

BACKGROUND

Insulin, leptin, and adiponectin regulate energy balance and may influence infant growth via their presence in human milk. Maternal body mass index has been associated with human milk insulin, leptin, and adiponectin concentrations, but results are inconsistent. Maternal serum hormone concentrations and fat mass may better characterize human phenotype and be more appropriate predictors of human milk insulin, leptin, and adiponectin.

RESEARCH AIM

To examine the associations of human milk insulin, leptin, and adiponectin with their concentrations in maternal circulation and with maternal fat mass.

METHODS

Insulin, leptin, and adiponectin were measured in serum and human milk at 1 month postpartum in 25 women. Total body fat mass and fat-free mass were measured using bioelectrical impedance analysis. Linear regression modeling was used to examine associations of serum hormone concentrations or fat mass with human milk insulin, leptin, and adiponectin after adjusting for covariates.

RESULTS

Serum insulin (p = .007), leptin (p < .001), and adiponectin (p < .001) were each associated with their respective concentrations in human milk. Fat mass was positively associated with insulin (p = .005) and leptin (p < .001), but not with adiponectin (p = .65), in human milk.

CONCLUSIONS

Human milk insulin, leptin, and adiponectin were positively associated with their concentrations in serum, and human milk insulin and leptin were associated with maternal fat mass. Future research is needed to elucidate the role of human milk hormones in infant energy balance and growth.

Potential sex differences in human milk leptin and their association with asthma and wheeze phenotypes: Results of the Ulm Birth Cohorts

BACKGROUND

The hormone leptin has been suggested to play a role in the respiratory and immune systems. Evidence on sex-specific concentrations of leptin in human milk and sex-specific associations with the development of asthma and wheeze has been put forward but is still scarce.

OBJECTIVE

To investigate whether male and female infants receive different levels of leptin through human milk and whether leptin is implicated in the development of asthma and wheeze in a sex-dependent manner using data from the two Ulm Birth Cohort studies.

METHODS

Leptin data were available from human milk samples collected at 6 weeks (Ulm Birth Cohort Study [UBCS, n = 678; Ulm SPATZ Health Study, n = 587]), and, in SPATZ only, at 6 months (n = 377) and 12 months (n = 66) of lactation. Sex-specific associations with doctor-diagnosed asthma and wheeze phenotypes were assessed in crude and adjusted models using logistic regression. Adjustments were made for maternal allergy, exclusive breastfeeding, infant age at the time of milk sampling, and child BMI z-score.

RESULTS

At 6 weeks, leptin levels (median [min, max], in ng/L) were higher in the milk for girls (197 [0.100, 4120]) than in milk for boys (159 [1.02, 3280], p = .045) in UBCS. No significant sex differences were observed in SPATZ (p = .152). There were no significant associations of leptin with asthma or wheeze in both studies, even in a sex-dependent manner (p > .05).

CONCLUSION

It remains unclear whether male and female infants receive different levels of leptin through human milk. However, leptin in human milk may not be associated with history and development of asthma and wheeze in a sex-specific manner.

Human Milk Lactose, Insulin, and Glucose Relative to Infant Body Composition during Exclusive Breastfeeding

Human milk (HM) components may influence infant growth and development. This study aimed to investigate relationships between infant body composition (BC) and HM lactose, insulin, and glucose (concentrations and calculated daily intakes (CDI)) as well as 24-h milk intake and maternal BC at 3 months postpartum. HM samples were collected at 2 months postpartum. Infant and maternal BC was assessed with bioimpedance spectroscopy. Statistical analysis used linear regression accounting for infant birth weight. 24-h milk intake and CDI of lactose were positively associated with infant anthropometry, lean body mass and adiposity. Higher maternal BC measures were associated with lower infant anthropometry, z-scores, lean body mass, and adiposity. Maternal characteristics including BC and age were associated with concentrations and CDI of HM components, and 24-h milk intake. In conclusion, 24-h intake of HM and lactose as well as maternal adiposity are related to development of infant BC.

Human Milk Metabolic Hormones: Analytical Methods and Current Understanding

Human milk (HM) contains a wide array of peptide hormones including leptin and adiponectin, which are involved in the regulation of infant growth and development. These essential hormones might play an important role in the regulation of metabolic reprogramming of the new-born infant. However, HM hormone studies are sparse and heterogeneous in regard to the study design, sample collection, preparation and analysis methods. This review discussed the limitations of HM hormone analysis highlighting the gaps in pre-analytical and analytical stages. The methods used to quantify HM metabolic hormones (leptin, adiponectin, ghrelin, insulin, obestatin, resistin and apelin) can be classified as immunoassay, immunosensor and chromatography. Immunoassay methods (ELISA and RIA) have been predominantly used in the measurement of these HM hormones. The relative validity parameters of HM hormones analysis are often overlooked in publications, despite the complexity and differences of HM matrix when compared to that of plasma and urine. Therefore, appropriate reports of validation parameters of methodology and instrumentation are crucial for accurate measurements and therefore better understanding of the HM metabolic hormones and their influences on infant outcomes.

Appetite-Regulating Hormones in Human Milk: A Plausible Biological Factor for Obesity Risk Reduction?

BACKGROUND

Human milk contains appetite-regulating hormones that may influence infant growth and obesity risk.

RESEARCH AIMS

We evaluated whether leptin, peptide tyrosine-tyrosine (PYY), glucagon-like peptide-1 (GLP-1), and ghrelin concentrations in human milk (1) changed during feeding (from foremilk to hindmilk) and during the first 6 months of infancy; (2) were explained by maternal factors; and (3) were associated with infant anthropometrics and growth.

METHODS

Mother-infant dyads (N = 22) participated. Samples of foremilk and hindmilk at 1 month postpartum were collected and analyzed for leptin, PYY, GLP-1, and ghrelin via radioimmunoassay and milkfat percentage estimated via creamatocrit. Samples were also collected in mothers (n = 15) who breastfed through 6 months. Anthropometrics were obtained on all mother-infant dyads at 1 month and all infants at 6 months and 12 months.

RESULTS

At 1 month, milk GLP-1 and milkfat concentration increased from foremilk to hindmilk (p ≤ .05) while leptin and PYY concentrations remained stable during feeding. Milk hormone concentrations and milkfat tended to decline overtime, with lower leptin, PYY, and ghrelin at 6 months versus 1 month (p < .05). At 1 month, milk leptin and milkfat content were associated with maternal markers of adiposity (r = 0.49-0.78, p < .001); whereas, milk PYY was correlated with maternal serum PYY concentration (r = 0.672, p = .001). Average 1-month milk concentrations of GLP-1 and leptin were negatively associated with weight-for-age z-scores at 6 months (r = -0.46, p < .05) and 12 months (r = -0.49, p < .05), respectively.

CONCLUSION

The content of certain appetite-regulating hormones in human milk may be influenced by maternal factors and play a role in infant growth; much needs to be learned about their role in the obesity protection of breastfed infants.

No Evidence for Sex-specificity in Vitamins C, E, and Fatty Acid Content of Human Milk from Healthy Polish Mothers

OBJECTIVES

Human milk (HM) is a complex fluid that meets the nutritional needs of infants. Its composition is associated with environmental, maternal, and fetal variables. It provides nutrients and bioactive substances, including cytokines, immunoglobulins, and constituents with antioxidative properties. Boys are reportedly more susceptible to oxidative stress. This study aimed to determine the relationship between infant sex and the antioxidants vitamins C and E, and the fatty acid (FA) profile of HM. Results of this investigation may infer sex differences for the composition of infant formulas.

METHODS

Thirty days after delivery, a sample of HM was collected from 152 healthy, non-smoking mothers of full-term new-borns (77 males) born in good clinical condition. After FAs were extracted from the fat component, they were converted into methyl esters and separated using high-performance gas chromatography. Tocopherol content was determined using a method described in a previous study. Vitamin C content was determined using reversed-phase high-performance liquid chromatography with ultraviolet detection, as described in the same study.

RESULTS

The study groups (male vs female offspring) did not differ in terms of vitamin and FA content in HM. The only difference found was in gondoic acid 20:1 (n-9), with a higher concentration in the HM of mothers with female offspring (mean 0.63 ± 0.18 vs 0.59 ± 0.15 g/100 g FA; P < 0.047).

CONCLUSIONS

Despite the acknowledged differences in the composition of HM associated with infant sex and the increased oxidative stress in males, antioxidant content did not appear to differ according to infant sex. These results suggest that there is no need for the antioxidant content of infant formulas to be sex-specific.

Reduction in Maternal Energy Intake during Lactation Decreased Maternal Body Weight and Concentrations of Leptin, Insulin and Adiponectin in Human Milk without Affecting Milk Production, Milk Macronutrient Composition or Infant Growth

Maternal diet has the potential to affect human milk (HM) composition, but very few studies have directly assessed the effect of maternal diets on HM composition. The primary aim of this study was to assess the effect of improving dietary quality in lactating women over 2 weeks on the concentrations of macronutrients and metabolic hormones in HM. The secondary aims were to assess the impact of the dietary intervention on 24 h milk production, maternal body composition and infant growth. Fifteen women completed a 1-week baseline period followed by a 2-week dietary intervention phase targeted towards reducing fat and sugar intake. Maternal anthropometric and body composition and infant growth measurements were performed weekly. Total 24 h milk production was measured before and after the dietary intervention, and HM samples were collected daily. Maternal intakes of energy (−33%), carbohydrate (−22%), sugar (−29%), fat (−54%) and saturated fat (−63%) were significantly reduced during the dietary intervention. HM insulin, leptin and adiponectin concentrations were 10–25% lower at the end of the dietary intervention, but HM concentrations of macronutrients were unaffected. Maternal body weight (−1.8%) and fat mass (−6.3%) were significantly reduced at the end of the dietary intervention, but there were no effects on 24 h milk production or infant growth. These results suggest that reducing maternal energy, carbohydrate, fat and sugar intake over a 2-week period is associated with significant reductions in HM insulin, leptin and adiponectin concentrations. These changes may be secondary to decreases in maternal weight and fat mass. The limited studies to date that have investigated the association between metabolic hormone concentrations in HM and infant growth raise the possibility that the changes in HM composition observed in the current study could impact infant growth and adiposity, but further studies are required to confirm this hypothesis.

Metabolic Hormone Profiles in Breast Milk From Mothers of Moderate-Late Preterm Infants Are Associated With Growth From Birth to 4 Months in a Sex-Specific Manner

Background: Differing environmental conditions experienced by mother-infant dyads may influence composition of the milk received by the infant. As a consequence, diverse milk compositional profiles may contribute to different postnatal outcomes, especially in infants facing adverse perinatal environments. We investigated whether variability in milk concentrations of key metabolic hormones is associated with different growth outcomes in infants born preterm, a perinatal complication known to impact on infant growth. Methods: Human milk samples were collected from 169 mothers of 191 infants enrolled in the DIAMOND trial, a randomized trial of nutrition for moderate-late preterm infants, at 5 and 10 days postpartum and again at 4 months' corrected age and analyzed for leptin, adiponectin and insulin-like growth factor (IGF)-1. Infant weight and body composition were measured at birth, discharge and 4 months' corrected age. Multiple linear regression models were used to examine correlations between milk hormone concentrations, weight z-scores and body composition at discharge and 4 months' corrected age, and weight gain from birth to 4 months' corrected age. Sex-specific interactions were examined. Results: Higher milk IGF-1 concentrations on day 5 after birth were associated with greater infant fat-free mass at 4 months' corrected age. Milk IGF-1 concentrations at 4 months were positively associated with fat mass and fat-free mass at 4 months in boys but not girls. Milk leptin concentrations on day 5 after birth were positively associated with fat mass at discharge from hospital, but negatively associated with fat mass at 4 months' corrected age. No significant association was found for milk adiponectin concentrations. Conclusion: Milk IGF-1 and leptin concentrations in mothers of moderate-late preterm babies are associated with different growth and body composition through to 4 months' corrected age and these associations are often different in boys and girls. The sex-specific effects of nutrient and hormone exposure during early life in preterm infants warrants further investigation to optimize the nutritional care these infants receive, particularly in hospital, where the same nutrition is provided to boys and girls.

Human Milk Hormone Intake in the First Month of Life and Physical Growth Outcomes in Preterm Infants

CONTEXT

Human milk contains hormones that regulate metabolism. Extrauterine growth restriction remains common among preterm infants, but the effect of ingesting milk hormones on preterm infant growth is poorly understood.

OBJECTIVE

To quantify associations of longitudinal exposure to leptin, adiponectin, and insulin in milk with physical growth of preterm infants.

DESIGN/METHODS

In 50 preterm neonates (median gestational age 29.4 weeks), we sampled maternal milk on day-of-life 7, 14, 21, and 28 and measured hormone levels in whole milk by ELISA. Milk leptin levels were available for a subset of 18 infants. We calculated milk hormone doses by multiplying the hormone level by the milk volume ingested on each day and estimated the area under the curve (AUC) to reflect longitudinal exposure. We analyzed associations of milk hormone exposure with growth outcomes in generalized estimated equations.

MAIN OUTCOME MEASURES

Weight gain velocity and z-scores in weight, length, head circumference, and body mass index at 36 weeks' postmenstrual age (PMA).

RESULTS

Higher leptin intake was associated with greater weight gain (2.17g/kg/day [95% CI, 1.31, 3.02]) and weight z-score at 36 weeks' PMA (0.30 [0.08, 0.53] higher z-score per tertile). Higher adiponectin intake was associated with greater length z-score (0.41 [0.13, 0.69]), however, this association was nullified after adjustment of protein and calorie intake. Higher adiponectin was associated with smaller head circumference z-score (-0.36 [-0.64, -0.07]). Insulin was not associated with growth outcomes.

CONCLUSIONS

Milk leptin and adiponectin exposures may affect growth of preterm infants. The long-term effects of milk hormones warrant further investigation.

Breast milk apelin level increases with maternal obesity and high-fat feeding during lactation

OBJECTIVE

Recent evidence indicates that levels of breast milk (BM) hormones such as leptin can fluctuate with maternal adiposity, suggesting that BM hormones may signal maternal metabolic and nutritional environments to offspring during postnatal development. The hormone apelin is highly abundant in BM but its regulation during lactation is completely unknown. Here, we evaluated whether maternal obesity and overnutrition impacted BM apelin and leptin levels in clinical cohorts and lactating rats.

METHODS

BM and plasma samples were collected from normal-weight and obese breastfeeding women, and from lactating rats fed a control or a high fat (HF) diet during lactation. Apelin and leptin levels were assayed by ELISA. Mammary gland (MG) apelin expression and its cellular localization in lactating rats was measured by quantitative RT-PCR and immunofluorescence, respectively.

RESULTS

BM apelin levels increased with maternal BMI, whereas plasma apelin levels decreased. BM apelin was also positively correlated with maternal insulin and C-peptide levels. In rats, maternal HF feeding exclusively during lactation was sufficient to increase BM apelin levels and decrease its plasma concentration without changing body weight. In contrast, BM leptin levels increased with maternal BMI in humans, but did not change with maternal HF feeding during lactation in rats. Apelin is highly expressed in the rat MG during lactation and was mainly localized to mammary myoepithelial cells. We found that MG apelin gene expression was up-regulated by maternal HF diet and positively correlated with BM apelin content and maternal insulinemia.

CONCLUSIONS

Our study indicates that BM apelin levels increase with long- and short-term overnutrition, possibly via maternal hyperinsulinemia and transcriptional upregulation of MG apelin expression in myoepithelial cells. Apelin regulates many physiological processes, including energy metabolism, digestive function, and development. Further studies are needed to unravel the consequences of such changes in offspring development.

Human Milk Exosomal MicroRNA: Associations with Maternal Overweight/Obesity and Infant Body Composition at 1 Month of Life

Among all the body fluids, breast milk is one of the richest sources of microRNAs (miRNAs). MiRNAs packaged within the milk exosomes are bioavailable to breastfeeding infants. The role of miRNAs in determining infant growth and the impact of maternal overweight/obesity on human milk (HM) miRNAs is poorly understood. The objectives of this study were to examine the impact of maternal overweight/obesity on select miRNAs (miR-148a, miR-30b, miR-29a, miR-29b, miR-let-7a and miR-32) involved in adipogenesis and glucose metabolism and to examine the relationship of these miRNAs with measures of infant body composition in the first 6 months of life. Milk samples were collected from a cohort of 60 mothers (30 normal-weight [NW] and 30 overweight [OW]/obese [OB]) at 1-month and a subset of 48 of these at 3 months of lactation. Relative abundance of miRNA was determined using real-time PCR. The associations between the miRNAs of interest and infant weight and body composition at one, three, and six months were examined after adjusting for infant gestational age, birth weight, and sex. The abundance of miR-148a and miR-30b was lower by 30% and 42%, respectively, in the OW/OB group than in the NW group at 1 month. miR-148a was negatively associated with infant weight, fat mass, and fat free mass, while miR-30b was positively associated with infant weight, percent body fat, and fat mass at 1 month. Maternal obesity is negatively associated with the content of select miRNAs in human milk. An association of specific miRNAs with infant body composition was observed during the first month of life, suggesting a potential role in the infant's adaptation to enteral nutrition.

Leptin administration during lactation leads to different nutritional, biometric, hemodynamic, and cardiac outcomes in prepubertal and adult female Wistar rats

Literature reports that insults, such as hormonal disturbances, during critical periods of development may modulate organism physiology and metabolism favoring cardiovascular diseases (CVDs) later in life. Studies show that leptin administration during lactation leads to cardiovascular dysfunction in young and adult male Wistar rats. However, there are sex differences regarding CVD. Thus, the present work aimed to investigate neonatal leptin administration's consequences on different outcomes in female rats at prepubertal and adult age. Newborn Wistar female rats were divided into two groups, Leptin and Control, receiving daily subcutaneous injections of this adipokine (8 μg/100 g) or saline for the first 10 of 21 d of lactation. Nutritional, biometric, hemodynamic, and echocardiographic parameters, as well as maximal effort ergometer performance, were determined at postnatal days (PND) 30 and 150. Leptin group presented lower food intake (p = 0.0003) and higher feed efficiency (p = 0.0058) between PND 21 and 30. Differences concerning echocardiographic parameters revealed higher left ventricle internal diameter (LVID) in systole (p = 0.0051), as well as lower left ventricle ejection fraction (LVEF) (p = 0.0111) and fractional shortening (FS) (p = 0.0405) for this group at PND 30. Older rats treated with leptin during lactation presented only higher LVID in systole (p = 0.0270). Systolic blood pressure and maximum effort ergometer test performance was similar between groups at both ages. These data suggest that nutritional, biometric, and cardiac outcomes due to neonatal leptin administration in female rats are age-dependent.

Associations of breastfeeding or formula feeding with infant anthropometry and body composition at 6 months

The objective of this study was to investigate the associations of mode of feeding with infant anthropometric and body composition variables at 6 months of age. We studied 259 infants whose exclusive mode of feeding (breast or formula) to 1 month was confirmed. Standard anthropometric characteristics of the infants (weight, length and weight‐for‐length z scores) were obtained, and body composition (total fat mass, fat‐free mass, trunk fat mass and body fat percent) was measured using dual‐energy X‐ray absorptiometry (DXA) at 6 months (±12 days). General linear models were used to test the associations of mode of feeding with infant anthropometric and body composition variables at 6 months after adjustment for maternal and infant covariates. In this cohort of predominantly breastfed, White infants of highly educated mothers, fat‐free mass was lower (P = .002), and trunk fat mass (P = .032) and body fat percent (P < .001) were greater in breastfed infants than in formula‐fed infants at 6 months of age. After adjustment for covariates, total fat‐free mass was significantly lower (β = −372 g, [SE = 125, P = .003]), and body fat percent was significantly greater (β = 3.30, [SE = 0.91, P < .001]) in breastfed infants than in formula‐fed infants. No other significant associations were observed. These findings support those of previous studies reporting greater fat‐free mass in formula‐fed infants during the first 6 months of life. Additional research is warranted to explore whether differences in infant body composition by mode of feeding persist throughout the life course and to assess causality.