Do gender and birth height of infant affect calorie of human milk? An association study between human milk macronutrient and various birth factors

Investigation of Relationships between Intakes of Human Milk Total Lipids and Metabolic Hormones and Infant Sex and Body Composition

Human milk (HM) composition, including metabolic hormones and lipids, is influenced by various factors, including lactation stage and, potentially, infant sex, which may affect infant body composition (BC) development. We aimed to: (a) characterize the longitudinal concentration and intake profiles of HM leptin, adiponectin, insulin, and total lipids; (b) determine if their concentrations and intakes differ by infant sex; and (c) explore the intakes relationships with the development of infant BC. Milk samples (n = 501) were collected from 82 mother-infant dyads during the first 6 months postpartum. Infant 24 h HM intake was measured, and the average cumulative HM component intakes were calculated. The statistical analysis used linear mixed modeling. Intakes of HM leptin, adiponectin, insulin, and total lipids increased to 1 month postpartum and then remained stable. HM intake and total lipids intake but not hormone intakes were positively associated with infant BC (fat-free mass, fat-free mass index, fat mass, fat mass index, percentage fat mass, and fat mass to fat-free mass ratio). HM component concentrations and intakes did not differ by sex. These findings advance our understanding of the temporal nature of HM components, emphasizing the role of infant 24 h HM and total lipids intake in development of infant lean and adipose tissue.

Breastfeeding Measurement - Teleological Considerations: Human Milk Collection for Research

We discuss the evolution and composition of breast milk and briefly describe how mammalian evolution resulted in lactation, which played a crucial role in infant growth and development. We focus on three teleological factors that significantly contribute to breast milk composition: (1) biological sex at birth, (2) gestational age, and (3) circadian rhythms. We also explain how these factors lead to variability in human milk composition. We emphasize the importance of standardizing the definitions of "preterm" and "term" to accurately study the effects of gestational age on milk composition. Finally, we discuss the role of the circadian clock in regulating lactation and the impact of breast milk on fetal and infant sleep. Investigators may integrate these critical factors when designing a research study that involves the collection of breast milk samples. Teleological factors greatly influence milk composition, and these factors may be considered when designing a study that requires breast milk. We provide both the rationale and application of solutions to address these factors.

Breast size in lactating women and the content of macronutrients in human milk

INTRODUCTION

Although the primary function of a woman's breast is milk synthesis, only a few studies have evaluated the relationship between breast size and human milk composition, showing equivocal results. This study aims to test if breast size during fully established lactation is related to energy density and content of macronutrients in human milk.

MATERIALS AND METHODS

Mothers of healthy, born-on-term infants at stage III of lactogenesis (N = 137) provided breast milk samples. Milk composition was analyzed using midinfrared transmission spectroscopy. The breast size index was calculated by dividing the breast by the circumference below the breast.

RESULTS

Stepwise forward linear regression showed a negative association between breast size index and lactose concentration in breast milk (β = -.242, p = .003). The final model, which includes breast size index, feeding frequency, and maternal energy intake together explained around 13% of the variance in breast milk lactose content (R2 adj = .126, p < .001). No statistically significant relationship was found between breast size index and milk's energy density, protein, and fat content.

CONCLUSION

This is the first study that shows a negative relationship between breast size during fully established lactation and lactose concentration in milk in a large sample size. No relationship between other macronutrients and breast size indicates that large breast size is not necessary for adequate milk production; however, it may contribute to an altered lactose concentration.

Relationship Between Maternal Age and Macronutrient Content of Colostrum

BACKGROUND

Little is known about the relationship between maternal age and the macronutrient content of colostrum.

RESEARCH AIMS

This study aimed to evaluate the relationship between maternal age and human milk macronutrient content by comparing the concentrations of lactose, proteins, and lipids in the colostrum of women with younger, moderate, and advanced maternal age.

METHODS

An observational, cross-sectional study was designed to compare the macronutrient concentrations in the colostrum of women aged < 20 years, 20 to 34 years, and > 34 years (younger, moderate, and advanced maternal age, respectively; n = 33 per group). For each participant, 3 ml of colostrum was collected by manual extraction from the right breast at 10 am, 39-48 hr after delivery, and analyzed using a Miris Human Milk Analyzer. Macronutrient concentrations were compared between the groups using analysis of variance. P < 0.05 was considered significant.

RESULTS

Mothers with moderate maternal age had a higher colostrum lipid concentration than those with younger or advanced maternal age (2.3 mg, SD = 1.4 mg vs. 1.5 mg, SD = 1.0 mg vs. 1.6 mg, SD = 0.9 mg, respectively; p = 0.007). Lactose and protein contents in the analyzed samples did not differ among the three study groups.

CONCLUSION

This study lends support to the potential variation of lipids in colostrum by maternal age and suggests individual adaptation to the nutritional components of milk to the needs of the infant may be beneficial.

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.

A nutritional supplement taken during preconception and pregnancy influences human milk macronutrients in women with overweight/obesity and gestational diabetes mellitus

Rational

Maternal overweight/obesity and gestational diabetes mellitus (GDM) are associated with an increased risk of their offspring developing overweight/obesity or type 2 diabetes later in life. However, the impacts of maternal overweight/obesity and dysglycemia on human milk (HM) macronutrient composition are not well understood.

Objective

Through a double-blind randomised controlled trial, we investigated the effects of maternal supplementation from preconception throughout pregnancy until birth on HM macronutrient concentrations, in association with maternal and infant factors including maternal pre-pregnancy body mass index (BMI) and GDM status. In addition, we aimed to characterise longitudinal changes in HM macronutrients.

Methods

The control supplement contained calcium, iodine, iron, β-carotene, and folic acid. The intervention supplement additionally contained zinc, vitamins B2, B6, B12, and D3, probiotics, and myo-inositol. HM samples were collected across seven time points from 1 week to 12 months from Singapore and/or New Zealand. HM macronutrient concentrations were measured using a MIRIS Human Milk Analyser. Potential differences in HM macronutrient concentrations were assessed using linear mixed models with a repeated measures design.

Results

Overall, HM macronutrient concentrations were similar between control and intervention groups. Among the control group, overweight/obesity and GDM were associated with higher HM fat and energy concentrations over the first 3 months. Such associations were not observed among the intervention group. Of note, mothers with GDM in the intervention group had lower HM fat by 10% (p = 0.049) and energy by 6% (p = 0.029) than mothers with GDM in the control group. Longitudinal changes in HM macronutrient concentrations over 12 months of lactation in New Zealand showed that HM fat and energy decreased in the first 6 months then increased until 12 months. HM lactose gradually decreased from 1 week to 12 months while crude protein decreased from 1 week to 6 months then remained relatively constant until 12 months of lactation.

Conclusion

Maternal overweight/obesity or GDM were associated with increased HM fat and energy levels. We speculate the intervention taken during preconception and pregnancy altered the impact of maternal BMI or GDM status on HM macronutrient composition. Further studies are required to identify the mechanisms underlying altered HM macronutrient concentration in the intervention group and to determine any long-term effects on offspring health.

Clinical trial registration

ClinicalTrials.gov, NCT02509988, Universal Trial Number U1111-1171-8056. Registered on 16 July 2015. This is an academic-led study by the EpiGen Global Research Consortium.

The impact of gender medicine on neonatology: the disadvantage of being male: a narrative review

This narrative non-systematic review addresses the sex-specific differences observed both in prenatal period and, subsequently, in early childhood. Indeed, gender influences the type of birth and related complications. The risk of preterm birth, perinatal diseases, and differences on efficacy for pharmacological and non-pharmacological therapies, as well as prevention programs, will be evaluated. Although male newborns get more disadvantages, the physiological changes during growth and factors like social, demographic, and behavioural reverse this prevalence for some diseases. Therefore, given the primary role of genetics in gender differences, further studies specifically targeted neonatal sex-differences will be needed to streamline medical care and improve prevention programs.

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.

Predictors of Human Milk Fatty Acids and Associations with Infant Growth in a Norwegian Birth Cohort

Triglyceride-bound fatty acids constitute the majority of lipids in human milk and may affect infant growth. We describe the composition of fatty acids in human milk, identify predictors, and investigate associations between fatty acids and infant growth using data from the Norwegian Human Milk Study birth cohort. In a subset of participants (n = 789, 30% of cohort), oversampled for overweight and obesity, we analyzed milk concentrations of detectable fatty acids. We modelled percent composition of fatty acids in relation to maternal body mass index, pregnancy weight gain, parity, smoking, delivery mode, gestational age, fish intake, and cod liver oil intake. We assessed the relation between fatty acids and infant growth from 0 to 6 months. Of the factors tested, excess pregnancy weight gain was positively associated with monounsaturated fatty acids and inversely associated with stearic acid. Multiparity was negatively associated with monounsaturated fatty acids and n-3 fatty acids while positively associated with stearic acid. Gestational age was inversely associated with myristic acid. Medium-chain saturated fatty acids were inversely associated with infant growth, and mono-unsaturated fatty acids, particularly oleic acid, were associated with an increased odds of rapid growth. Notably, excessive maternal weight gain was associated with cis-vaccenic acid, which was further associated with a threefold increased risk of rapid infant growth (OR = 2.9, 95% CI 1.2–6.6), suggesting that monounsaturated fatty acids in milk may play a role in the intergenerational transmission of obesity.

Sex differences in preterm nutrition and growth: the evidence from human milk associated studies

Sexual dimorphism of the fetus manifests itself even during pregnancy. Preterm births are more common in pregnancies with male fetuses. Intrauterine and postnatal growth nomograms are sex-specific. The human milk composition in term infants appears to be sex-specific. Early nutrition has sex-specific effects and neurodevelopmental outcomes. A large same-sex twin study suggests that a mother's own milk (MOM) provides sex-specific growth advantages probably related to the calibration of a mother's milk based on her newborn's sex. Formula composition does not vary with infant sex, which may be one reason why body composition data favors the use of MOM over formula. However, given the lack of data on this subject, we need more detailed information on how the sex-specific micronutrients in MOM influence infant well-being. We also need more information to ascertain the sex differences in infants' macronutrient requirements, such as whether preterm females have higher fat requirements and preterm males have higher protein requirements for optimal growth and neurodevelopmental outcomes. This information may also influence milk banking and the use of donor human milk (DBM). Further research may help us determine if we should provide sex-specific DBM to those preterm infants who cannot get their MOM.

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.

Sex-dependence and comorbidities of the early-life adversity induced mental and metabolic disease risks: Where are we at?

Early-life adversity (ELA) is a major risk factor for developing later-life mental and metabolic disorders. However, if and to what extent ELA contributes to the comorbidity and sex-dependent prevalence/presentation of these disorders remains unclear. We here comprehensively review and integrate human and rodent ELA (pre- and postnatal) studies examining mental or metabolic health in both sexes and discuss the role of the placenta and maternal milk, key in transferring maternal effects to the offspring. We conclude that ELA impacts mental and metabolic health with sex-specific presentations that depend on timing of exposure, and that human and rodent studies largely converge in their findings. ELA is more often reported to impact cognitive and externalizing domains in males, internalizing behaviors in both sexes and concerning the metabolic dimension, adiposity in females and insulin sensitivity in males. Thus, ELA seems to be involved in the origin of the comorbidity and sex-specific prevalence/presentation of some of the most common disorders in our society. Therefore, ELA-induced disease states deserve specific preventive and intervention strategies.

Changes in Human Milk Fat Globule Composition Throughout Lactation: A Review

There has been a growing interest in understanding how the relative levels of human milk fat globule (MFG) components change over the course of lactation, how they differ between populations, and implications of these changes for the health of the infant. In this article, we describe studies published over the last 30 years which have investigated components of the MFG in term milk, focusing on changes over the course of lactation and highlighting infant and maternal factors that may influence these changes. We then consider how the potential health benefits of some of the milk fat globule membrane (MFGM) components and derived ingredients relate to compositional and functional aspects and how these change throughout lactation. The results show that the concentrations of phospholipids, gangliosides, cholesterol, fatty acids and proteins vary throughout lactation, and such changes are likely to reflect the changing requirements of the growing infant. There is a lack of consistent trends for changes in phospholipids and gangliosides across lactation which may reflect different methodological approaches. Other factors such as maternal diet and geographical location have been shown to influence human MFGM composition. The majority of research on the health benefits of MFGM have been conducted using MFGM ingredients derived from bovine milk, and using animal models which have clearly demonstrated the role of the MFGM in supporting cognitive and immune health of infants at different stages of growth and development.

Mode of Neonatal Delivery Influences the Nutrient Composition of Human Milk: Results From a Multicenter European Cohort of Lactating Women

Background

The effect of the mode of neonatal delivery (cesarean or vaginal) on the nutrient composition of human milk (HM) has rarely been studied. Given the increasing prevalence of cesarean section (C-section) globally, understanding the impact of C-section vs. vaginal delivery on the nutrient composition of HM is fundamental when HM is the preferred source of infant food during the first 4 postnatal months.

Objective

This study aimed to evaluate the association between mode of delivery and nutrient composition of HM in the first 4 months of life.

Design

Milk samples were obtained from 317 healthy lactating mothers as part of an exploratory analyses within a multicenter European longitudinal cohort (ATLAS cohort) to study the HM composition, and its potential association with the mode of delivery. We employed traditional mixed models to study individual nutrient associations adjusted for mother’s country, infant birth weight, parity, and gestational age, and complemented it, for the first time, with a multidimensional data analyses approach (non-negative tensor factorization, NTF) to examine holistically how patterns of multiple nutrients and changes over time are associated with the delivery mode.

Results

Over the first 4 months, nutrient profiles in the milk of mothers who delivered vaginally (n = 237) showed significantly higher levels of palmitoleic acid (16:1n-7), stearic acid (18:0), oleic acid (18:1n-9), arachidic acid (20:0), alpha-linolenic acid (18:3n-3), eicosapentaenoic acid (20:5n-3), docosahexenoic acid (22:6n-3), erucic acid (22:1n-9), monounsaturated fatty acids (MUFA)%, calcium, and phosphorus, whereas the ratios of arachidonic acid/docosahexaenoic acid (ARA/DHA) and n-6/n-3, as well as polyunsaturated fatty acids (PUFA)% were higher in milk from women who had C-sections, in the unadjusted analyses (p < 0.05 for all), but did not retain significance when adjusted for confounders in the mixed models. Using a complementary multidimension data analyses approach (NTF), we show few similar patterns wherein a group of mothers with a high density of C-sections showed increased values for PUFA%, n-6/n-3, and ARA/DHA ratios, but decreased values of MUFA%, 20:1n-9, iodine, and fucosyl-sialyl-lacto-N-tetraose 2 during the first 4 months of lactation.

Conclusion

Our data provide preliminary insights on differences in concentrations of several HM nutrients (predominantly fatty acids) among women who delivered via C-section. Although these effects tend to disappear after adjustment for confounders, given the similar patterns observed using two different data analytical approaches, these preliminary findings warrant further confirmation and additional insight on the biological and clinical effects related to such differences early in life.

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.

Effect of Vaginal Delivery on Lactose Content of Human Milk

OBJECTIVE

The macronutrients of human milk are considered essential nutritional sources in the first few months of a newborn's life. The present study aimed to investigate the effect of delivery mode on the macronutrients of human milk.

METHODS

This retrospective cohort study was conducted on 102 women who gave birth by cesarean section or vaginal delivery between September 2019 and November 2019. The participants were requested to provide their milk samples on day 15 ± 1 after childbirth.

RESULTS

There were no significant differences between the two groups (cesarean and vaginal delivery) regarding the sociodemographic characteristics and intake of fat, carbohydrate, protein, and energy. The lactose level was significantly higher in women who gave birth by vaginal delivery (adjusted mean difference, 1.2 (95 % CI 0.02- 1.82)). For other macronutrients, there were no statistically significant differences between the two groups.

CONCLUSION

The vaginal delivery might influence the mature milk lactose level.

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.

Osteopontin Levels in Human Milk Are Related to Maternal Nutrition and Infant Health and Growth

Background: Osteopontin (OPN) is a glycosylated phosphoprotein found in human tissues and body fluids. OPN in breast milk is thought to play a major role in growth and immune system development in early infancy. Here, we investigated maternal factors that may affect concentrations of OPN in breast milk, and the possible associated consequences for the health of neonates. Methods: General characteristics, health status, dietary patterns, and anthropometric measurements of 85 mothers and their babies were recorded antenatally and during postnatal follow-up. Results: The mean concentration of OPN in breast milk was 137.1 ± 56.8 mg/L. Maternal factors including smoking, BMI, birth route, pregnancy weight gain, and energy intake during lactation were associated with OPN levels (p < 0.05). Significant correlations were determined between body weight, length, and head circumference, respectively, and OPN levels after one (r = 0.442, p = < 0.001; r = −0.284, p = < 0.001; r = −0.392, p = < 0.001) and three months (r = 0.501, p = < 0.001; r = −0.450, p = < 0.001; r = −0.498, p = < 0.001) of lactation. A negative relation between fever-related infant hospitalizations from 0–3 months and breast milk OPN levels (r = −0.599, p < 0.001) was identified. Conclusions: OPN concentrations in breast milk differ depending on maternal factors, and these differences can affect the growth and immune system functions of infants. OPN supplementation in infant formula feed may have benefits and should be further investigated.

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.

Maternal and Infant Factors Influencing Human Milk Oligosaccharide Composition: Beyond Maternal Genetics

Maternal genetics is a key determinant of human milk oligosaccharide (HMO) composition in human milk. Beyond genetic status, other factors influencing the HMO profile are poorly defined. Thus, we aimed to review the existing evidence on the associations between nongenetic maternal and infant factors and HMO composition. A systematic search was performed on PubMed and Web of Science (without a time restriction) to identify any relevant studies published. In total, 1056 results were obtained, of which 29 articles were selected to be included in this review. The range of factors investigated include lactation stage, maternal pre-pregnancy BMI (ppBMI), maternal age, parity, maternal diet, mode of delivery, infant gestational age, and infant sex. The data suggest that, beyond maternal genetics, HMO composition seems to be influenced by all these factors, but the underlining mechanisms remain speculative. The published evidence is discussed in this review, along with potential implications for infant growth and development. For example, 2'-fucosyllactose, which was reportedly increased in mothers with higher ppBMIs, was also associated with increased infant weight and height. In addition, greater levels of sialylated HMOs after preterm birth may support brain development in these infants.

In Utero HIV Exposure and the Early Nutritional Environment Influence Infant Neurodevelopment: Findings from an Evidenced Review and Meta-Analysis

The developing brain is especially vulnerable to infection and suboptimal nutrition during the pre- and early postnatal periods. Exposure to maternal human immunodeficiency virus (HIV) infection and antiretroviral therapies (ART) in utero and during breastfeeding can adversely influence infant (neuro) developmental trajectories. How early life nutrition may be optimised to improve neurodevelopmental outcomes for infants who are HIV-exposed has not been well characterised. We conducted an up-to-date evidence review and meta-analysis on the influence of HIV exposure in utero and during breastfeeding, and early life nutrition, on infant neurodevelopmental outcomes before age three. We report that exposure to maternal HIV infection may adversely influence expressive language development, in particular, and these effects may be detectable within the first three years of life. Further, while male infants may be especially vulnerable to HIV exposure, few studies overall reported sex-comparisons, and whether there are sex-dependent effects of HIV exposure on neurodevelopment remains a critical knowledge gap to fill. Lastly, early life nutrition interventions, including daily maternal multivitamin supplementation during the perinatal period, may improve neurodevelopmental outcomes for infants who are HIV-exposed. Our findings suggest that the early nutritional environment may be leveraged to improve early neurodevelopmental trajectories in infants who have been exposed to HIV in utero. A clear understanding of how this environment should be optimised is key for developing targeted nutrition interventions during critical developmental periods in order to mitigate adverse outcomes later in life and should be a priority of future research.

The Effect of Infant's Sex on Human Milk Macronutrients Content: An Observational Study

Background: Sex differences in infant mortality and neonatal morbidity have been previously documented. Few studies, with conflicting results, have investigated the interaction between human milk (HM) macronutrients and energy content and infant sex. Objective: To test the null hypothesis that HM macronutrients content will not be affected by infant's sex. Materials and Methods: We compiled previously generated data on macronutrients content of colostrum samples and mature milk samples collected from lactating mothers of healthy term infants. Macronutrient content was measured using mid-infrared spectroscopy. Results: A total of 324 milk samples were included in the analysis consisting of 189 colostrum and 135 mature milk samples. There were 92 female and 97 male infants in the colostrum group and 65 female and 70 male infants in the mature milk group. Maternal age, gestational age, mode of delivery and percentage of large for gestational age, small for gestational age, and appropriate for gestational age were similar between female and male groups at all stages of lactation. Birth weight in male infants was significantly higher than in female infants (3389.5 ± 444.6 versus 3229.2 ± 415 g, p = 0.016). There were no statistically significant differences in macronutrient contents between the female and male groups at all stages studied. Conclusion: Macronutrients and energy content in colostrum and mature milk collected from mothers of term infants were unaffected by the sex of their offspring.

Impact of Infant and Maternal Factors on Energy and Macronutrient Composition of Human Milk

The present study investigates the influence of selected infant and maternal factors on the energy and macronutrient composition of mature human milk (HM). The study enrolled 77 mothers at 4-8 weeks postpartum. Each mother provided 1 sample of HM. Each extracted HM sample was formed by mixing four subsamples of HM, each of which were obtained in one predefined 6-h periods of the day. Among maternal factors, the analysis included: anthropometric data before and after pregnancy; weight gain in pregnancy; body composition, assessed using the Maltron BioScan 920-II to analyze bioimpedance; and dietary intake, assessed with three-day dietary records. Among the neonatal factors, birth weight and length, number of daily feedings and type of delivery were included. The composition of HM, including energy content, protein, fat and carbohydrate concentrations, was analyzed using the Miris human milk analyzer. Pearson's and Spearman's correlation coefficients and multivariable logistic regression models were used to analyze the association between the selected maternal and infant factors and HM milk composition. It was found that total protein content of HM was correlated with pre-pregnancy BMI (Spearman rho = 0.238; p = 0.037), current lean body mass (Spearman rho = -0.293, p = 0.01) and total water content (Spearman rho = -0.315, p = 0.005). Carbohydrates were the only macronutrients whose composition was significantly affected by the infant factors. It was reported that higher carbohydrate content was associated with male sex (OR = 4.52, p = 0.049). Our results show that maternal and infant factors, especially maternal pre-pregnancy and current nutritional status and infant sex, interact and affect HM composition, suggesting that macronutrient and energy content in HM may be determined in pregnancy and may have unique compositional profile for every mother-infant dyad.

The Role of Infant Sex on Human Milk Composition

Objective: Human milk (HM) is the most necessary and complete food for infants and their survival. It is a dynamic system influenced by different factors such as the sex of the infant. The study of the factors affecting the composition of mother's milk can provide us better insight into the nutritional needs of infants with different sex and improve the nutrition of babies who do not have access to HM. This study aimed to study the effects of infant sex on mother's milk composition. Methods: Sixty-one mother's milk samples were collected from mothers with female or male infants and divided into two (32 sons, 29 daughters) groups. The samples were analyzed by the Lacto-Scan milk analyzer and the obtained data were compared between the groups. Results: The results showed that the mean fat content in the milk samples of mothers with female infants (daughters group) (3.42 ± 1.80%) was significantly (p = 0.029) higher than that in mothers with male infants (sons group) (2.53 ± 1.18%). However, the sons group had higher (p = 0.024) levels of salts (0.76 ± 0.14%) compared with the daughters group (0.67 ± 0.18%). There was no significant (p > 0.05) difference in other indices between the groups. Conclusions: The sex of the infant is one of the important factors affecting the composition of mother's milk. The difference in the composition of mother's milk may reflect the differences in metabolic substrate needed for optimal growth and development in female and male infants.

Calorie intake is associated with weight gain during transition phase of nutrition in female extremely low birth weight infants

We sought to determine whether there are sex-based differences in the requirements for calories or protein for optimal growth during the transition phase (TP) when an extremely low birth weight (ELBW) infant, defined as a preterm infant with a birth weight of < 1000 g, is progressing from parenteral to enteral feeds. A retrospective review of ELBW infants born from 2014 to 2016 was performed at a tertiary NICU. Infants with necrotizing enterocolitis, short bowel syndrome, or chromosomal anomalies were excluded. TP was defined as the period when the infant's enteral feeds were increased from 30 up to 120 ml/kg/day while weaning parenteral nutrition (PN). Effects of sex and protein-calorie intake on the change in growth parameters from the beginning to the end of TP were analyzed. Pre-TP growth percentiles and calorie and protein intake were similar in both sexes. There was a significant (r = 0.22, p = 0.026) correlation of total calorie intake with a change in weight percentiles (wt.pc) for the whole group, but on sex-specific analysis, this correlation was more robust and significant only in girls (r = 0.28, p = 0.015). Protein intake did not correlate with the changes in wt.pc in either sex. Despite a similar intake of calories and protein during the TP, we found a significant decrease in wt.pc only in girls. More extensive studies are needed to understand the sex-based differences in caloric needs and metabolic rate in ELBW infants.

Neutral Human Milk Oligosaccharides Are Associated with Multiple Fixed and Modifiable Maternal and Infant Characteristics

We aimed to identify if maternal and infant factors were associated with neutral human milk oligosaccharides (HMOs) variability and examined the associations between HMOs concentration and infant growth and disease status in healthy Chinese mothers over a 6-month lactation period. We recruited mothers and their full-term infants as our subjects. At 1–5 days, 8–14 days, 4 weeks, and 6 months postpartum, all participants were interviewed to collect breast milk samples, obtain follow-up data and measure infant length and weight at their local hospital. A total of 23 neutral HMOs were analyzed by high performance liquid chromatography (HPLC)- mass spectrometer (MS). Secretor and Lewis phenotype were determined by the concentration of 2′-fucosyllactose (2′-FL) and Lacto-N-fucopentaose (LNFP)-II. The associations between maternal and infant factors with HMOs concentrations were investigated. A total of 464 human breast milk samples were collected from 116 mothers at four different time points. In total, 76.7% mothers were found to be Secretor and Lewis positive phenotype (Se+Le+), 17.2% were Se-Le+, 4.3% were Se+Le-, and 1.7% were Se-Le-. Several individual HMOs, including 2′-FL, Lactodifucotetraose (LDFT), LNFP-I were determined by Secretor phenotype. Most individual HMOs decreased at the later stage of lactation, except 3′-FL. We suggest that Secretor phenotype and lactation stage could influence most of the neutral HMOs. Concentrations of specific HMOs may be associated with maternal age, allergic history, pre-pregnancy body mass index (BMI), parity, delivery mode, infant gestational age and gender.

Comparison of Changes in Breast Milk Macronutrient Content During the First Month in Preterm and Term Infants

Purpose: This study aims to achieve a better understanding of the trend of maternal milk macronutrient levels by analyzing protein, lipid, carbohydrate, and energy content of the breast milk and investigate the possible confounders of macronutrient content during the first 4 weeks of lactation to meet the specific needs of babies, guide optimum fortification of maternal milk. Patients and Methods: Breast milk from 39 mothers who had delivered preterm infants and 21 mothers of term infants were collected longitudinally for the first 4 weeks of lactation. Fresh milk samples were obtained on day 3, 7, 14, and 28 of lactation. The samples are analyzed using mid-infrared milk analyzer (MIRIS Human Milk Analyzer, HMA; Miris AB, Uppsala, Sweden). Results: Colostral milk protein concentrations of mothers of both preterm and term infants were significantly higher and the protein content of the samples decreased in time, according to the week of lactation during the study period. In contrast, fat, carbohydrate, and energy content were lowest in the colostral milk in both groups. When preterm and term milks were compared, fat and carbohydrate levels on 28th day and energy levels on 14th and 28th days were significantly higher in term milks, whereas no difference in protein contents were observed between the two groups on each time period. Mode of delivery was found to have statistically significant correlation with protein content of the milk. Conclusion: This longitudinal study revealed significant changes in analyzed macronutrient contents of mother's milk over the first 4 week period.

Human milk fatty acid composition is associated with dietary, genetic, sociodemographic, and environmental factors in the CHILD Cohort Study

BACKGROUND

Fatty acids are a vital component of human milk. They influence infant neurodevelopment and immune function, and they provide ∼50% of milk's energy content.

OBJECTIVES

The objectives of this study were to characterize the composition of human milk fatty acids in a large Canadian birth cohort and identify factors influencing their variability.

METHODS

In a subset of the CHILD cohort (n = 1094), we analyzed milk fatty acids at 3-4 mo postpartum using GLC. Individual and total SFAs, MUFAs, and n-3 and n-6 PUFAs were analyzed using SD scores and principal component analysis (PCA). Maternal diet, sociodemographic, health, and environmental factors were self-reported. Single-nucleotide polymorphisms were assessed in the fatty acid desaturase 1 (FADS1-rs174556) and 2 (FADS2-rs174575) genes.

RESULTS

Fatty acid profiles were variable, with individual fatty acid proportions varying from 2- to >30-fold between women. Using PCA, we identified 4 milk fatty acid patterns: "MUFA and low SFA," "high n-6 PUFA," "high n-3 PUFA," and "high medium-chain fatty acids." In multivariable-adjusted analyses, fish oil supplementation and fatty cold water fish intake were positively associated with DHA and the "high n-3 PUFA" pattern. Mothers carrying the minor allele of FADS1-rs174556 had lower proportions of arachidonic acid (ARA; 20:4n-6). Independent of selected dietary variables and genetic variants, Asian ethnicity was associated with higher linoleic acid (18:2n-6) and total n-3 PUFAs. Ethnic differences in ARA were explained by FADS1 genotype. Maternal obesity was independently associated with higher total SFAs, the "high medium-chain fatty acid" pattern, and lower total MUFAs. Lactation stage, season, study site, and maternal education were also independently associated with some milk fatty acids. No associations were observed for maternal age, parity, delivery mode, or infant sex.

CONCLUSIONS

This study provides unique insights about the "normal" variation in the composition of human milk fatty acids and the contributing dietary, genetic, sociodemographic, health, and environmental factors. Further research is required to assess implications for infant health.

Prevalence and determinants of HIV shedding in breast milk during continued breastfeeding among Zambian mothers not on antiretroviral treatment (ART): A cross-sectional study

The risk of postnatal HIV transmission exists throughout the breastfeeding period. HIV shedding in breast milk beyond six months has not been studied extensively. The aim of this study was to determine prevalence and determinants of HIV shedding in breast milk during continued breastfeedingA cross-sectional study was nested in the PROMISE-PEP trial in Lusaka, Zambia to analyze breast milk samples collected from both breasts at week 38 post-partum (mid-way during continued breastfeeding). We measured concurrent HIV deoxyribonucleic acid (DNA) and HIV ribonucleic acid (RNA) as proxies for cell-associated HIV (CAV) and cell-free HIV (CFV) shedding in breast milk respectively. Participants' socio-demographic date, concurrent blood test results, sub clinical mastitis test results and contraceptive use data were available. Logistic regression models were used to identify determinants of HIV shedding in breast milk (detecting either CAV or CFV).The prevalence of HIV shedding in breast milk at 9 months post-partum was 79.4% (95%CI: 74.0 - 84.0). CAV only, CFV only and both CAV and CFV were detectable in 13.7%, 17.3% and 48.4% mothers, respectively. The odds of shedding HIV in breast milk decreased significantly with current use of combined oral contraceptives (AOR: 0.37; 95%CI: 0.17 - 0.83) and increased significantly with low CD4 count (AOR: 3.47; 95%CI: 1.23 - 9.80), unsuppressed plasma viral load (AOR: 6.27; 95%CI: 2.47 - 15.96) and severe sub-clinical mastitis (AOR: 12.56; 95%CI: 2.48 - 63.58).This study estimated that about 80% of HIV infected mothers not on ART shed HIV in breast milk during continued breastfeeding. Major factors driving this shedding were low CD4 count, unsuppressed plasma viral load and severe sub-clinical mastitis. The inverse relationship between breast milk HIV and use of combined oral contraceptives needs further clarification. Continued shedding of CAV may contribute to residual postnatal transmission of HIV in mothers on successful ART.

Feasibility of Standardized Human Milk Collection in Neonatal Care Units

Research in human lactation is a growing field. However, difficulties in studying human milk originate from the dynamicity of its composition. Using standardized collection protocols is mandatory to minimize variation and warrant comparability of findings across different studies. Yet, information on the feasibility of collecting human milk with standardized procedures, especially in neonatal units, are lacking. The present study aims to report on the feasibility and difficulties to collect human milk according to a standardized protocol, during early lactation from women who gave birth to preterm infants. Human milk was collected from 129 mothers of moderate- to late-preterm infants according to two variations of a standard protocol which differed for number of collection time-points. Collection rates and adherence to the sampling protocol were evaluated together with reason for missed collection. Collection of ≥1 sample was successful for 80% of the mothers. However adherence to the standard protocol was overall low (36% and 27%). Collection rates were different between the two protocol variations (73% against 92%, p ≤ 0.001). Amongst the reason for missed collection, low milk supply was the most recurrent (40%). Our findings show that while collecting human milk in neonatal units is achievable, obtaining standard and comparable samples results challenging.

Longitudinal Analysis of Macronutrient Composition in Preterm and Term Human Milk: A Prospective Cohort Study

Background: Mother’s own milk is the optimal source of nutrients and provides numerous health advantages for mothers and infants. As they have supplementary nutritional needs, very preterm infants may require fortification of human milk (HM). Addressing HM composition and variations is essential to optimize HM fortification strategies for these vulnerable infants. Aims: To analyze and compare macronutrient composition in HM of mothers lactating very preterm (PT) (28 0/7 to 32 6/7 weeks of gestational age, GA) and term (T) infants (37 0/7 to 41 6/7 weeks of GA) over time, both at similar postnatal and postmenstrual ages, and to investigate other potential factors of variations. Methods: Milk samples from 27 mothers of the PT infants and 34 mothers of the T infants were collected longitudinally at 12 points in time during four months for the PT HM and eight points in time during two months for the T HM. Macronutrient composition (proteins, fat, and lactose) and energy were measured using a mid-infrared milk analyzer, corrected by bicinchoninic acid (BCA) assay for total protein content. Results: Analysis of 500 HM samples revealed large inter- and intra-subject variations in both groups. Proteins decreased from birth to four months in the PT and the T HM without significant differences at any postnatal time point, while it was lower around term equivalent age in PT HM. Lactose content remained stable and comparable over time. The PT HM contained significantly more fat and tended to be more caloric in the first two weeks of lactation, while the T HM revealed higher fat and higher energy content later during lactation (three to eight weeks). In both groups, male gender was associated with more fat and energy content. The gender association was stronger in the PT group, and it remained significant after adjustments. Conclusion: Longitudinal measurements of macronutrients compositions of the PT and the T HM showed only small differences at similar postnatal stages in our population. However, numerous differences exist at similar postmenstrual ages. Male gender seems to be associated with a higher content in fat, especially in the PT HM. This study provides original information on macronutrient composition and variations of HM, which is important to consider for the optimization of nutrition and growth of PT infants.

Maternal obesity and the human milk metabolome: associations with infant body composition and postnatal weight gain

BACKGROUND

Maternal obesity is a risk factor for childhood obesity; this is a major public health concern given that ∼40% of pregnant women are either overweight or obese. Whether differences in milk composition in lean compared with obese women contribute to childhood obesity is unclear.

OBJECTIVES

We aimed to analyze relationships between maternal obesity and human milk metabolites, infant body composition, and postnatal weight gain.

METHODS

This was a prospective study in which mothers intending to breastfeed exclusively, and their newborn infants, were enrolled at delivery (n = 35 mother-infant pairs). We excluded mothers with diabetes, other medical conditions, or pregnancy complications. Participants were grouped by maternal prepregnancy BMI <25 (lean) or ≥25 kg/m2 (overweight/obese). We analyzed infant body composition by dual-energy X-ray absorptiometry and used untargeted liquid chromatography-gas chromatography-mass spectrometry to measure the milk content of 275 metabolites at 1 and 6 mo postpartum.

RESULTS

At 1 mo postpartum, 10 metabolites differed between overweight/obese and lean groups with nominal P < 0.05, but none was altered with a false discovery rate <0.25. Many differentially abundant metabolites belonged to the same chemical class; e.g., 4/10 metabolites were nucleotide derivatives, and 3/10 were human milk oligosaccharides. Milk adenine correlated positively with both continuously distributed maternal BMI and with infant adiposity and fat accrual. Analysis of milk composition at 6 mo postpartum revealed 20 differentially abundant metabolites (P < 0.05) in overweight/obese compared with lean women, including 6 metabolites with a false discovery rate of <0.25. At both 1 and 6 mo, human milk abundance of 1,5-anhydroglucitol, which has not previously been described in milk, was positively associated with maternal BMI.

CONCLUSIONS

Maternal obesity is associated with changes in the human milk metabolome. While only a subset of metabolites correlated with both maternal and infant weight, these point to potential milk-dependent mechanisms for mother-child transmission of obesity. This trial was registered at www.clinicaltrials.gov as NCT02535637.

The antioxidant components of milk and their role in processing, ripening, and storage: Functional food

The current rate of population growth is so fast that, to feed this massive population, a 2-fold increase in land is required for the production of quality food. Improved dietary products such as milk and its products with antioxidant properties and functional foods of animal origin have been utilized to prevent chronic diseases. The designer milk contains low fat and less lactose, more protein, modified level of fatty acids, and desired amino acid profiles. The importance of milk and its products is due to the presence of protein, bioactive peptides, conjugated linoleic acid, omega-3 fatty acid, Vitamin D, selenium, and calcium. These constituents are present in milk product, play a key role in the physiological activities in human bodies, and act as anti-inflammatory, anti-tumor, antioxidant, hypocholesterolemic, immune boosting, and antimicrobial activities. Consumer awareness regarding benefits of designer foods such as milk and its products is almost non-existent worldwide and needs to be established to reach the benefits of designer food technologies in the near future. The main objective of this review was to collect data on the antioxidant properties of milk and its constituents which keep milk-derived products safe and preserved.

Sex-Specific Human Milk Composition: The Role of Infant Sex in Determining Early Life Nutrition

Male and female infants respond differentially to environmental stimuli, with different growth and neurodevelopmental trajectories. Male infants are more likely to be disadvantaged when subjected to adversity and show a higher risk of perinatal complications. However, the underlying causes of this sex-bias are not well defined and optimising the early life nutritional care may be necessary to minimise the “male disadvantage” that may be experienced early in life. Experimental models have demonstrated that animal milk composition differs according to offspring sex, suggesting that the tailoring of early life nutrition may be one mechanism to maximise health protection and development to infants of both sexes. However, evidence for a sex-specificity in human milk composition is limited and conflicting, with studies documenting higher milk energy content for either male or female infants. These data show sex differences, however, there has been limited compositional analysis of the current data nor strategies proposed for how sex-specific compositional differences in early life nutrition may be used to improve infant health. The present narrative review highlights that an improved understanding of sex-specific human milk composition is essential for promoting optimal infant growth and development.

Fatty acid composition of breast milk in Galicia (NW Spain): A cross-country comparison

Based on the premise that the fatty acid composition of human milk can be substantially altered by diet, the current study investigated the fatty acid profile (fattyacidome) of breast milk in Galicia, a small region located in the north-west of Spain and characterized by the Southern European Atlantic Diet (SEAD). A cross-country comparison was also performed to assess worldwide variety and diet impact, reviewing the profiles reported various European, North and South American, Asian and African countries and Australia. Galician human milk appeared similar to the rest of Europe, with some particular features related to the SEAD (dairy, pork, beef and sunflower and olive oils), such as relatively high levels of linoleic acid and lower α-linolenic acid. The results also showed the existence of woman-specific profiles and significant changes over lactation in some fatty acids. Worldwide, the fatty acid profiles were similar, with the clear exception of Asiatic breast milk. The impact of fatty acids on infant health warrants further investigation.

"Bed Side" Human Milk Analysis in the Neonatal Intensive Care Unit: A Systematic Review

Human milk analyzers can measure macronutrient content in native breast milk to tailor adequate supplementation with fortifiers. This article reviews all studies using milk analyzers, including (i) evaluation of devices, (ii) the impact of different conditions on the macronutrient analysis of human milk, and (iii) clinical trials to improve growth. Results lack consistency, potentially due to systematic errors in the validation of the device, or pre-analytical sample preparation errors like homogenization. It is crucial to introduce good laboratory and clinical practice when using these devices; otherwise a non-validated clinical usage can severely affect growth outcomes of infants.