Effects of smoking, mother's age, body mass index, and parity number on lipid, protein, and secretory immunoglobulin A concentrations of human milk

Maternal and Infant Predictors of Human Milk Macronutrient and Energy Concentrations in Rural Bangladesh: An Observational Cohort Study

BACKGROUND

Human milk macronutrient (protein, fat, and carbohydrate) and energy concentrations vary based on maternal and infant factors and time postpartum.

OBJECTIVES

This study aimed to determine the change in milk macronutrient and energy concentrations from approximately 2 to 5 months postpartum and identify factors associated with this variation among a lactation cohort in Bangladesh.

METHODS

In this prospective observational lactation cohort in rural Sylhet, Bangladesh, we collected hand-expressed mid-feed human milk samples and analyzed macronutrient concentrations using mid-infrared spectroscopy. We used the Wilcoxon rank-sum test to compare macronutrient and energy concentrations between time points and mixed linear regression to determine associations between predictors [maternal body mass index (BMI), maternal mid-upper arm circumference, infant gestational age, and infant small for gestational age status] and repeated measures of milk macronutrient and energy concentrations in models adjusted for parity, nicotine, and wealth index.

RESULTS

We enrolled 99 participants. From visit 1 (∼2 mo) to visit 2 (∼5 mo), median milk protein concentration decreased from 1.4 g/dL [interquartile range (IQR): 1.1-1.6 g/dL] to 0.8 g/dL (IQR: 0.6-1.1 g/dL), median fat concentration decreased from 4.6 g/dL (IQR: 3.8-5.5 g/dL) to 2.8 g/dL (IQR: 2.1-3.7 g/dL), and median energy concentration decreased from 22.7 kcal/oz (IQR: 20.6-25.1 kcal/oz) to 17.5 kcal/oz (IQR: 15.6-19.9 kcal/oz). Maternal overweight status was associated with a lower carbohydrate concentration (2 mo-mean difference: -0.16 g/dL; 95% CI: -0.28, -0.03 g/dL; 5 mo-mean difference: -0.14 g/dL; 95% CI: -0.26, -0.02; reference = normal BMI).

CONCLUSIONS

The decline of protein, fat, and energy concentrations over time is a potential concern for Bangladesh's vulnerable population of human milk-fed infants, as these nutrients have implications for infant growth and neurodevelopment.

Exploring the association between human breast milk lipids and early adiposity rebound in children: A case-control study

OBJECTIVES

Adiposity rebound (AR) corresponds to the start of the second rise in the body mass index curve during infant growth. Early AR (before age 5) confers increased risk of adiposity and metabolic disorders but is less likely to occur in breastfed infants. Although lipids in breast milk are important in child growth, information is limited regarding which lipids are involved in AR. The object of this study was to explore the association between breast milk lipids and AR status in children.

METHODS

We designed a case-control study of 184 mother-child pairs (AR cases: n = 93; controls: n = 91) included from the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study. Breast milk was collected 1 month postpartum and comprehensive lipid analysis was performed. Partial least square-discriminant analysis was used to explore candidate lipids, and multivariable logistic regression analysis was used to evaluate associations with the AR status of children.

RESULTS

We detected 667 lipid molecules in 12 lipid classes in breast milk. Partial least square-discriminant analysis revealed the association of fatty acid-hydroxy fatty acid (FAHFA) and cholesterol ester (ChE) with AR status. Multivariable logistic regression analysis showed that in pairs with exclusive breastfeeding at 1 month postpartum, FAHFA (odds ratio 1.57 [95% confidence interval, 1.06-2.32]) was positively associated with early AR, and ChE (odds ratio 0.55 [95% confidence interval, 0.36-0.86]) was negatively associated.

CONCLUSIONS

Breast milk lipids (FAHFA, ChE) associated with the AR status of children, indicating the potential to regulate a child's adiposity and possible metabolic disorders in adulthood.

The association between maternal body mass index and breast milk composition: a systematic review

CONTEXT

Breast milk composition is influenced by many factors, ranging from maternal nutritional status to infant sex. Previous studies have explored the relationship between maternal body mass index (BMI) and breast milk composition; however, the findings have been inconsistent and controversial.

OBJECTIVE

To systematically review the evidence on the association of maternal weight and BMI with breast milk composition.

DATA SOURCES

The PubMed and Scopus databases were searched up to May 3, 2023, using the following search strategy: ("maternal weight" OR "maternal BMI" OR "mother's weight" OR "mother's BMI") AND ("maternal milk" OR "human milk" OR "breast milk").

DATA EXTRACTION

A total of 83 publications, involving data from more than 11 310 lactating women, were identified. All extracted data were compiled, compared, and critically analyzed.

DATA ANALYSIS

Overall, maternal BMI was associated with higher levels of leptin and insulin, and the ratio of omega-6 to omega-3 polyunsaturated fatty acids in breast milk. However, no conclusive associations were found between maternal BMI and the levels of energy, macronutrients, micronutrients, and other components of breast milk.

CONCLUSIONS

This systematic review provides robust evidence supporting a positive correlation between maternal BMI and breast milk concentrations of leptin, insulin, and the omega-6 to omega-3 polyunsaturated fatty acid ratio. Nevertheless, disparities in findings are noticeable for other constituents of breast milk. To comprehensively grasp the influence of maternal weight and BMI on breast milk composition, further research endeavors are imperative.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42023458667.

Feeding Method, Nicotine Exposure, and Growth during Infancy

Objective

To answer 3 questions: (1) Are infants breastfed by smokers at risk of rapid weight and length gain? (2) Is rapid growth during infancy partially attributable to ingestion of smokers' breastmilk? (3) If so, what are the implications for breastfeeding by smokers?

Study design

Using data from the Norwegian Mother, Father and Child Cohort Study and Medical Birth Registry of Norway (n = 54 522), we examined changes in weight, length, weight-for-length z-score (WFLZ) during infancy in the context of maternal smoking (0, 1-10, or >10 cigarettes/day) and feeding method during the first 6 months (breastfed, formula fed, mixed fed). We fit generalized linear models, adding a smoking by feeding method interaction term to evaluate the effect of ingesting smokers' breastmilk.

Results

Breastfed infants of both light and heavy smokers experienced WFLZ gains of 0.05 (95% CI, 0.01-0.09) and 0.13 (95% CI, 0.07-0.18), respectively. Among mixed-fed infants, only heavy maternal smoking predicted WFLZ gain (0.10; 95% CI, 0.05-0.16). Among exclusively formula-fed infants, maternal smoking did not predict rapid growth. Interaction models suggest that infants ever breastfed (ie, breastfed and mixed-fed groups combined) by heavy smokers gained weight (100 g; 95% CI, 30-231) and length (2.8 mm; 95% CI, 0.1-5.6), attributable to ingesting smoker's breastmilk.

Conclusions

Infants breastfed by smokers experience rapid growth; some of these gains are attributable to ingesting smokers' breastmilk. Among infants breasted by light smokers, these gains are within the range of normative growth patterns for healthy, breastfed infants.

Research progress on factors affecting the human milk metabolome

Human milk is the gold standard for infant nutrition and contains macronutrients, micronutrients, and various bioactive substances. The human milk composition and metabolite profiles are complex and dynamic, complicating its specific analysis. Metabolomics, a recently emerging technology, has been used to identify human milk metabolites classes. Applying metabolomics to study the factors affecting human milk metabolites can provide significant insights into the relationship between infant nutrition, health, and development and better meet the nutritional needs of infants during growth. Here, we systematically review the current status of human milk metabolomic research, and related methods, offering an in-depth analysis of the influencing factors and results of human milk metabolomics from a metabolic perspective to provide novel ideas to further advance human milk metabolomics.

"OMICS" in Human Milk: Focus on Biological Effects on Bone Homeostasis

Human milk (HM) is a complex biofluid rich in nutrients and bioactive compounds essential for infant health. Recent advances in omics technologies-such as proteomics, metabolomics, and transcriptomics-have shed light on the influence of HM on bone development and health. This review discusses the impact of various HM components, including proteins, lipids, carbohydrates, and hormones, on bone metabolism and skeletal growth. Proteins like casein and whey promote calcium absorption and osteoblast differentiation, supporting bone mineralization. Long-chain polyunsaturated fatty acids like docosahexaenoic acid (DHA) contribute to bone health by modulating inflammatory pathways and regulating osteoclast activity. Additionally, human milk oligosaccharides (HMOs) act as prebiotics, improving gut health and calcium bioavailability while influencing bone mineralization. Hormones present in HM, such as insulin-like growth factor 1 (IGF-1), leptin, and adiponectin, have been linked to infant growth, body composition, and bone density. Research has shown that higher IGF-1 levels in breast milk are associated with increased weight gain, while leptin and adiponectin influence fat mass and bone metabolism. Emerging studies have also highlighted the role of microRNAs (miRNAs) in regulating key processes like adipogenesis and bone homeostasis. Furthermore, microbiome-focused techniques reveal HM's role in establishing a balanced infant gut microbiota, indirectly influencing bone development by enhancing nutrient absorption. Although current findings are promising, comprehensive longitudinal studies integrating omics approaches are needed to fully understand the intricate relationships among maternal diet, HM composition, and infant bone health. Bridging these gaps could offer novel dietary strategies to optimize skeletal health during infancy, advancing early-life nutrition science.

Tobacco Smoke Exposure and Lactation

Tobacco smoke exposure remains a significant public health concern, particularly for lactating women and their infants. Despite widespread awareness of the harms of smoking during pregnancy, many women continue to smoke postpartum, directly impacting lactation success and infant health. Studies have shown that nicotine, the primary component of tobacco smoke, inhibits prolactin production and the milk ejection reflex, resulting in a decreased milk supply and poor breastfeeding outcomes. Additionally, the presence of harmful chemicals in tobacco smoke, such as cadmium and lead, can accumulate in breast milk, exposing infants to toxic substances with potential long-term health implications. Maternity professionals play a crucial role in supporting smoking cessation efforts among postpartum women, providing evidence-based counseling, resources, and referrals to cessation programs. This review aims to provide an update for maternity professionals on the effects of tobacco smoke exposure on lactation and breastfeeding outcomes. In this review, we will explore the physiological mechanisms through which tobacco smoke components can interfere with lactation. Furthermore, we will discuss the challenges faced by lactating women who smoke, including increased risk of mastitis, reduced breastfeeding duration, and impaired infant growth and development. Finally, we will highlight emerging research on novel interventions to reduce the adverse effects of tobacco smoke exposure on lactation, including pharmacological treatments and behavioral interventions tailored to postpartum women.

Macronutrients in Human Milk and Early Childhood Growth-Is Protein the Main Driver?

BACKGROUND

Infant growth trajectories reflect current health status and may predict future obesity and metabolic diseases. Human milk is tailored to support optimal infant growth. However, nutrient intake rather than milk composition more accurately predicts growth outcomes. Although the role of protein leverage in infant growth is unclear, protein intake is important for early infancy growth.

MATERIALS AND METHODS

This study of exclusively breastfeeding mothers with allergies (n = 161) from the Infant Fish Oil Supplementation Study assessed relationships between intake of human milk macronutrients and infant growth. Human milk fat, protein and lactose concentrations were measured at 3 months postpartum, and infant daily intakes were estimated using an average milk intake of 800 mL/day.

RESULTS

Higher human milk protein:energy ratio was associated with higher weight-for-age z-score at 2.5 years compared to 3 months and higher body mass index-for-age z-score change (6 months to 1 year compared to 3-6 months). Maternal atopy and birth season (summer) were negatively associated with human milk lactose concentration. Passive smoke exposure was associated with reduced energy and fat concentrations and increased lactose:energy ratio.

CONCLUSIONS

Our results indicate that intake of human milk macronutrients may impact early childhood growth.

Systematic Characterization of the Oligosaccharide Profile of Human Milk in Rural Areas of Central China: Quantitative Tracking of Human Milk Oligosaccharide Composition during 12 Months of Lactation

This study investigates changes in human milk oligosaccharide (HMO) composition over a 12 month breastfeeding period in rural central China. The HMO profiles of 97 mothers were analyzed by graphitized carbon liquid chromatography-electrospray ionization-mass spectrometry. This method was simple to prepare samples and can simultaneously and absolutely quantify at least 20 neutral and acidic HMOs. All mothers were classified into four milk groups based on the presence or absence of specific α-1,2 and α-1,4-fucosylated HMOs. The main oligosaccharides in milk groups I and II were 2'-FL, LDFT, LNFP-I, and LNDFH-I, while LNT, 3-FL, LNFP-II, LNFP-V, LNDFH-II, and DFLNH-b were predominant in milk groups III and IV. Additionally, the lactation period was the primary factor affecting the concentration of individual HMOs. The concentrations of most HMOs decreased with lactation and stabilized after 180 days. However, the concentrations of 3-FL, LDFT, and LNDFH II increased gradually over the lactation period, and the concentration of 3'-SL decreased during early lactation (5-180 days) but increased during later lactation (180-365 days). Furthermore, Spearman correlation analysis revealed that maternal factors and infant factors may also affect the concentration of various HMOs. These findings provide fundamental insights for the development of a comprehensive human milk database.

Smoking-induced suppression of β-casein in milk is associated with an increase in miR-210-5p expression in mammary epithelia

Smoking during lactation harmfully affects the amount and constituents of breast milk. Infants who consume breast milk containing miR-210-5p may have a higher risk of brain-related diseases. We investigated whether smoking during lactation decreases β-casein concentrations in milk and whether miR-210-5p expression is involved in smoking-induced β-casein suppression. During lactation, maternal CD1 mice were exposed to cigarette smoke (1.7 mg of tar and 14 mg of nicotine) in a smoke chamber for 1 h twice/day for five consecutive days. Control mice were placed in an air-filled chamber equivalent in size to the smoke chamber, with maternal separation times identical to those of the smoked mice. Maternal exposure to smoke during lactation significantly decreased β-casein expression in the mammary epithelia of smoked mice compared to that of the control mice. Signal transducer and activator transcription 5 (STAT5) and phosphorylated STAT5 (pSTAT5) are transcription factors involved in β-casein expression. In the mammary epithelia of smoked mice, the pSTAT5 and STAT5 levels were significantly lower, and miR-210-5p expression was significantly higher than that of the control mice. The β-casein, pSTAT5, and STAT5 protein levels of miR-210-5p mimic-transfected human mammary epithelial MCF-12A cells were significantly lower than those of control siRNA-transfected cells. These results indicate that smoke exposure led to an increase in miR-210-5p expression in mammary epithelium and a decrease in pSTAT5 and β-casein protein levels through the inhibition of STAT5 expression. Moreover, nicotine treatment decreased β-casein protein levels and increased miR-210-5p expression in non-malignant human mammary epithelial MCF-12A cells in a concentration-dependent manner, demonstrating that nicotine significantly affects the β-casein and miR-210-5p levels of breast milk. These results highlight the adverse effects of smoking on breast milk, providing essential information for healthcare professionals and general citizens.

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.

The effect of extra virgin olive oil (EVOO) on fat mass and fat-free mass for breastfeeding mothers (0-24 months) in Makassar City, Indonesia

BACKGROUND

Extra Virgin Olive Oil (EVOO) is a fat source classified as monounsaturated fatty acid. Previous studies have shown that 47.5% of breastfeeding mothers have less fat intake when compared to the Adequacy of Nutrition Rate (RDA). EVOO consumption can improve the composition of breast milk. However, no research has been found regarding the body composition of breastfeeding mothers after consuming EVOO. This study aims to determine the effect of EVOO on the body composition of breastfeeding mothers 0-24 months.

MATERIALS AND METHODS

The study was conducted at the Sudiang Raya and Tamalanrea Health Centers in Makassar City with a randomized clinical trial design from January to February 2023. The sample was breastfeeding mothers 0-24 months divided into the intervention group (EVOO and Nutrition Education, n = 17) and the control (Nutrition Education, n = 17). Instruments with Bioelectrical Impedence Analysis tools. Data analysis using t-test.

RESULTS

The sample is breastfeeding mothers aged between ≤19 and >35 years. The results of the analysis showed that the average pre-post test, % fat mass (FM) P = 0.426 and % fat free mass (FFM) P = 0.508 (P > 0.05), meant that there was no significant difference. Between the two groups there was no significant difference at the end of the study, %FM P = 0.469 and %FFM P = 0.529 (P > 0.05).

CONCLUSIONS

In the intervention group that was given EVOO, it was possible to maintain%FM and%FFM in the normal percentage range, while in the control group, there was a decrease from the normal to less/low range.

Factors affecting total protein and lactoferrin in human milk

The aim of this study was to investigate factors affecting total, true protein and lactoferrin (Lf) concentrations in human milk (HM) and to evaluate the changes in protein concentrations over the course of lactation (first to sixth month postpartum). HM samples were collected from exclusively breastfeeding mothers during six time periods (1-6 months postpartum); 198 breast milk samples were collected in total. The concentrations of total and true protein in HM were determined using the MIRIS human milk analyzer (HMA). The assessment of HM protein content was also performed in skim HM samples and quantified by bicinchoninic methods with the Bicinchoninic Acid Protein Assay Kit. In turn, Lf content in skim HM samples was determined by the enzyme-linked immunosorbent assay (ELISA) in accordance with a slightly modified procedure. In the first month of lactation total protein concentration was negatively correlated with maternal pre-pregnancy BMI (r = - 0.397; p = 0.022), whereas in the third month postpartum, positive correlation with maternal age was found (r = 0.399; p = 0.021). Considering Lf concentration, in the first month of lactation, it was positively correlated with baby's birth weight (r = 0.514; p = 0.002). In the next months (from second to sixth) no relationships between Lf concentration and maternal and infants' factors were observed. The concentration of protein and Lf in HM changes dynamically throughout lactation. Maternal and infant characteristics may impact the HM protein and Lf content, especially in the first month postpartum.

Nutritional composition of human milk and its association with maternal and perinatal factors

OBJECTIVE

The objective of this study was to evaluate the influence of maternal and perinatal factors on the nutritional composition of human milk.

METHODS

A cross-sectional study was conducted between November 2018 and January 2020, with 181 donors selected in Tertiary Health Units of the Unified Health System - from one collection station and five Human Milk Banks. Data were collected through a standardized questionnaire. To be fit to be a donor in a Human Milk Banks and produce mature milk were the eligibility criteria to participate in the study. We excluded milk samples with Dornic acidity above 8° D. The dependent variables were the macronutrients of human milk (i.e., carbohydrates, proteins, lipids, and total energy), that were analyzed using spectroscopy with the Miris Human Milk Analyzer™. The maternal and perinatal factors were the independent variables.

RESULTS

Women with pre-gestational obesity and gestational weight gain above the recommendation showed a lower protein concentration compared to eutrophic women (median=0.8, interquartile range (IQR): 0.7-0.9 vs. median=0.8, and IQR: 0.8-1.0) and those with adequate gestational weight gain (median=0.8, IQR: 0.7-0.9 vs. median=0.9, and IQR: 0.8-1.0), respectively. The other analyzed factors (i.e., maternal habits, comorbidities, and perinatal factors) were not associated with the nutritional composition of human milk.

CONCLUSIONS

The assessment of factors associated with the nutritional composition of human milk is extremely important to assist postpartum care. Pre-gestational obesity and inadequate gestational weight gain were the only factors statistically associated with the nutritional composition of human milk as they impacted its protein content.

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.

Physical activity in lactating women influences SARS-CoV-2-specific antibodies in human milk

Background

Moderate exercise results in a significant increase in serum and salivary immunoglobulins. Maternal physical activity might therefore also be a factor influencing antibody levels in human milk. This study aims to determine the influence of physical activity on SARS-CoV-2-specific Immunoglobulin A (IgA) in human milk and Immunoglobulin G (IgG) in serum.

Methods

In this prospective cross-sectional cohort study, all lactating women in the Netherlands were eligible to participate. SARS-CoV-2-specific IgA in human milk and IgG in serum were determined using an enzyme-linked immunosorbent assay (ELISA). Data on performed physical activity was collected using the Short Questionnaire to Assess Health enhancing physical activity (SQUASH), which includes intensity and duration of the performed activity.

Findings

In total, 356 out of 2312 lactating women tested positive for SARS-CoV-2-specific antibodies in serum. Of them, 323 filled in the questionnaire and were included in the analysis. An association between the activity score and SARS-CoV-2-specific antibodies in human milk (B = 1·035, 95·0% CI = 1·019 to 1·052, p = 0·042) and serum (B = 1·019, 95·0% CI = 1·009 to 1·029, p = 0·048) was demonstrated. No association was found between the duration of physical activity and SARS-CoV-2-specific antibodies in human milk or serum.

Interpretation

Our findings suggest that physical activity is beneficial for the levels of SARS-CoV-2-specific antibodies in human milk and serum, with the intensity of the physical activity being the most important contributor to this relationship. A higher level of antibodies in human milk might provide better immunological protection for infants against COVID-19.

The effects of freezing and thawing on mature human milk's contains: A systematic review

OBJECTIVE

To conduct a systematic review on the effects of freezing and thawing mature human milk at -18 to -20°C for different periods of time on the macronutrients, micronutrients and bioactive content of milk.

DESIGN

Before starting the research, the study protocol was recorded in the 'PROSPERO' database. Eleven databases were searched, and eight studies were included in this review. The articles were published between January 2010 and June 2020.

MEASUREMENTS AND FINDINGS

Total protein content increased when milk was frozen for 2 days, but this decreased significantly when milk was frozen for >1 week. Total carbohydrate content also increased when milk was frozen for 2 days, and no significant change was observed when milk was frozen for >1 week. Energy content decreased when milk was frozen for >8 weeks. Total fat content decreased as the freezing period of milk increased, and total free fatty acid content increased. Thirty days of freezing led to a non-significant decrease in the vitamin E content of milk. Freezing did not lead to changes in immunological factors in human milk, but decreases in glutathione peroxidase, antioxidant capacity and lactoferrin were observed.

KEY CONCLUSIONS

In order to maintain the nutritional and immunological properties of human milk after freezing and thawing, families, especially mothers, should be informed about the effects of storing milk this way. After expressing milk, it is recommended that the date should be written on the freezer bag, so that milk is frozen for a shorter period of time before use.

Maternal Diet Influences Human Milk Protein Concentration and Adipose Tissue Marker

(1) Background: Adequate protein intake plays an essential role in growth and neurodevelopment, especially in preterm infants. We investigated the effects of maternal diet and body mass index (BMI) on human milk (HM) composition. (2) Methods: HM samples were obtained from 136 lactating mothers (BMI: 18.0−36.7 kg/m2), of which 93% gave birth to preterm infants. Macronutrient content in HM was measured by mid-infrared transmission spectroscopy. Leptin and adiponectin were analyzed using appropriate ELISAs. Maternal diet was determined by 24-h recall. (3) Results: Significant positive associations were found between protein, fat, carbohydrate and energy intake, and levels of corresponding macronutrients in HM, especially in protein concentrations (p < 0.001). An increased protein intake was positively correlated with adiponectin (p < 0.001) and leptin (p = 0.035) in HM. Maternal BMI was positively associated with a higher protein level in HM (p < 0.05), as well as with a higher dietary protein intake (p < 0.05). (4) Conclusions: Knowledge of maternal diet and BMI impacting HM composition is essential to optimize the feeding of newborn infants. This is especially relevant in the nutritional management of preterm infants; it can be utilized in approaches to improve growth rates and the appropriate development of infants and to prevent obesity.

Does Fetal Growth Adequacy Affect the Nutritional Composition of Mothers' Milk?: A Historical Cohort Study

OBJECTIVE

The study aimed to assess the association between intrauterine growth of preterm infants and energy and macronutrient contents in their mothers' milk.

STUDY DESIGN

A historical cohort of mothers of preterm infants was assessed according to offspring's intrauterine growth. Fetal growth restriction (FGR) was defined as small-for-gestational age or appropriate for gestational age with fetal growth deceleration. During the first 4 weeks after delivery, the composition of daily pool samples of mothers' milk was measured by using a mid-infrared human milk analyzer. Explanatory models for milk energy, true protein, total carbohydrate, and fat contents were obtained by generalized additive mixed effects regression models.

RESULTS

In total, 127 milk samples were analyzed from 73 mothers who delivered 92 neonates. Energy content was significantly higher in mothers with chronic hypertension (average: +6.28 kcal/dL; 95% confidence interval [CI]: 0.54-12.01; p = 0.034) and for extremely preterm compared with very preterm infants (average: +5.95 kcal/dL; 95% CI: 2.16-9.73; p = 0.003), and weakly associated with single pregnancies (average: +3.38 kcal/dL; 95% CI: 0.07-6.83; p = 0.057). True protein content was significantly higher in mothers with chronic hypertension (average: +0.91 g/dL; 95% CI: 0.63-1.19; p < 0.001) and with hypertension induced by pregnancy (average: +0.25 g/dL, 95% CI: 0.07-0.44; p = 0.007), and for extremely preterm compared with very and moderate preterm infants (average: +0.19; 95% CI: 0.01-0.38; p = 0.043 and +0.28 g/dL; 95% CI: 0.05-0.51; p = 0.017, respectively). Fat content was weakly and negatively associated with FGR, both in SGA infants and AGA infants with fetal growth deceleration (average: -0.44 g/dL; 95% CI: -0.92 to -0.05; p = 0.079 and average: -0.36 g/dL; 95% CI: -0.74 to -0.02; p = 0.066, respectively).

CONCLUSION

Energy and macronutrient contents in mothers' milk of preterm infants was significantly and positively associated with the degree of prematurity and hypertension. The hypothesis that the composition of milk is associated with FGR was not demonstrated.

KEY POINTS

· Energy and protein are higher for more immature infants.. · Energy and/or protein is higher in hypertension.. · Fat may be lower for infants with intrauterine growth restriction..

Influence of maternal and perinatal factors on macronutrient content of very preterm human milk during the first weeks after birth

OBJECTIVE

To identify changes in macronutrient content of very preterm human milk associated with perinatal factors.

STUDY DESIGN

Milk macronutrients were measured on weeks 1, 2, 4 and 8 with mid-infrared transmission spectrometers.

RESULT

We assessed 625 samples (from 117 mothers and 130 very preterm infants). Average concentrations were: protein 1.3 ± 0.3 g/dl, carbohydrates 7.3 ± 0.6 g/dl, fat 3.7 ± 1.0 g/dl and energy 296.0 ± 41.0 kJ/dl (70.7 kcal/dl). Gestational age negatively correlated with protein (rho: -0.307, p < 0.001) and energy (r: -0.193, p = 0.003). Advanced maternal age, gestational age and intrauterine growth restriction were independently associated with milk protein content over the first 4 weeks (adjusted R²: 0.113, p = 0.002).

CONCLUSION

These findings may help neonatologists identify patients fed Mother´s Own Milk who are at increased risk of poor postnatal growth.

Human milk pH is associated with fortification, postpartum day, and maternal dietary intake in preterm mother-infant dyads

OBJECTIVE

To compare pH of human milk types (mother's own milk (MOM), pasteurized donor human milk (PDHM), fortified MOM, and fortified PDHM) fed to preterm infants.

STUDY DESIGN

This observational study consisted of 63 mother-infant dyads < 34 weeks gestation. Human milk samples (n = 245), along with maternal factors, were collected for pH analysis. pH of MOM was analyzed over the course of lactation accounting for fortification status, postpartum day, and storage conditions.

RESULTS

Mean pH of MOM was slightly acidic at 6.60 ± 0.28, which was significantly higher (p < 0.05) than other milk types. pH of MOM varied by fortification, postpartum day, and maternal vegetable/fiber intake. There was a significant interaction between fortification status and postpartum day; pH of MOM decreased over time, while pH of fortified MOM increased over time.

CONCLUSION

pH of human milk varied by type. pH of MOM was significantly associated with fortification status, postpartum day, and maternal vegetable/fiber intake.

Cannabis use during lactation may alter the composition of human breast milk

BACKGROUND

Cannabis is often used by women to manage symptoms of morning sickness during pregnancy, and postpartum stress and anxiety. While exclusive breastfeeding has been recommended for the first 6 months of an infant's life, the presence of cannabinoids in the milk of cannabis users complicates this recommendation. The objective of this study was to investigate the effect of maternal cannabis use on changes in the levels of macronutrients and bioactive factors in breast milk.

METHODS

Milk was collected from women who were 6-8 weeks postpartum and were either using cannabis post-delivery, had used cannabis during pregnancy, or were non-users. Levels of cannabinoids, macronutrients, lactose, and SIgA were assessed in the milk of all subjects.

RESULTS

THC was detected in the milk of women who reported cannabis use during lactation (n = 13, median: 22 ng/mL). Carboxy-THC, 11-hydroxy-THC, CBD, and CBN were also detected in the milk of women who used cannabis postpartum. Relative to non-users (n = 17), lactose levels were higher and SIgA levels were significantly lower in the milk of subjects who used cannabis during lactation (n = 14).

CONCLUSIONS

The presence of cannabinoids, along with altered lactose and SIgA levels in the milk of cannabis users, may have implications for infant health.

IMPACT

Metabolites of cannabis are found in breast milk and can accumulate in higher concentrations with ongoing consumption, which is concerning for potential exposure among infants born to mothers who consume cannabis. This work reports that lactose levels are increased and SIgA levels are decreased in the breast milk of cannabis users, relative to the milk of non-users. Change in levels of lactose and SIgA in the milk of cannabis users may have significant implications on infant health, which must be investigated in the future to better inform mothers.

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.

Profiles of total and sn-2 fatty acid of human mature milk and their correlated factors: A cross-sectional study in China

Fatty acid (FA) in breast milk is beneficial to the growth and neurodevelopment of infants. However, the structure profiles of breast milk FAs and the influencing factors which are crucial for normal function have not been fully elucidated. This study aimed to characterize the profiles of total and sn-2 FAs in human mature milk based on two representative urban areas in China and explore potential sociodemographic determinants. Mothers (n = 70) at 40–100 d postpartum from Beijing and Danyang were recruited according to unified inclusion and exclusion criteria. Total and sn-2 FA compositions were examined by gas chromatography and quantified. Using the Spearman correlation and multiple regression model, we found that the location and maternal education level were the most conspicuous correlated factor. The milk of mothers from Beijing had higher levels of the n-6 series of long-chain polyunsaturated fatty acids (LCPUFA) (C20:2, C20:3n-6, C20:4n-6, n-6PUFA/n-3PUFA, LA/ALA, and ARA/DHA) than that of Danyang, while the opposite was observed in the n-3 series of LCPUFA (C18:3n-3 and Total n-3PUFA). Compared to the milk of mothers with a high school degree or below, those with a bachelor's degree or above had lower SFAs (C10:0, C12:0, C14:0, and Total SFA), n-3 series of LCPUFA (C18:3n-3 and Total n-3PUFA), C18:1n-9t, and higher n-6 series of LCPUFA (C18:2n-6c, C20:2, C20:4n-6, Total n-6PUFA, and n-6PUFA/n-3PUFA). Maternal age, infant gender, pre-conception body mass index (BMI), parity, delivery mode, and gestational weight gain were also associated with total FAs. However, fewer associations were found between the above factors and sn-2 FAs. This study will promote an understanding of human breast milk's lipid profile and help develop a formula more suitable for infants.

Maternal Stress and Human Milk Antibodies During the COVID-19 Pandemic

Importance

SARS-CoV-2-specific antibodies in human milk might protect the breastfed infant against COVID-19. One of the factors that may influence human milk antibodies is psychological stress, which is suggested to be increased in lactating women during the COVID-19 pandemic.

Objective

To determine whether psychological stress is increased in lactating women during the COVID-19 pandemic, and if maternal stress is associated with the level of SARS-CoV-2-specific antibodies in human milk.

Design

Population-based prospective cohort study.

Setting

Data collection took place in the Netherlands between October 2020 and February 2021.

Participants

Lactating women living in the Netherlands were eligible to participate in this study. In total, 2310 women were included.

Exposures

Stress exposure during the COVID-19 pandemic was determined using the Perceived Stress Scale (PSS) questionnaire and maternal lifetime stress was determined by the Life Stressor Checklist - revised (LSC-r) questionnaire.

Main Outcomes and Measures

Stress experience during the COVID-19 pandemic was compared with a pre-pandemic cohort. SARS-CoV-2-specific antibodies in human milk were measured using an Enzyme-Linked Immunosorbent Assay (ELISA) with the Spike protein of SARS-CoV-2. The association between maternal stress and human milk antibodies was determined using a multiple regression model.

Results

The PSS score of lactating mothers was not increased during the pandemic compared to the PSS score in the prepandemic cohort. Six hundred ninety-one participants had SARS-CoV-2-specific antibodies and were included in the regression models to assess the association between maternal stress and human milk antibodies. No association was found between PSS scores and human milk antibodies. In contrast, the LSC-r score was negatively associated with SARS-CoV-2-specific IgA in human milk (β = 0.98, 95% CI: 0.96-0.997, p = 0.03).

Conclusions and Relevance

Our results suggest that lactating women in the Netherlands did not experience higher stress levels during the COVID-19 pandemic. Breastfed infants of mothers with high chronic stress levels receive lower amounts of antibodies through human milk, which possibly makes them more vulnerable to respiratory infections. This emphasizes the importance of psychological wellbeing during lactation.

DYNAMICS OF SIgA CONTENT IN BREAST MILK WHEN RISK FACTORS AND LACTATIONAL CHARACTERISTICS ARE CONSIDERED

The leading role associated with an anti-infective action of breast milk belongs to secretory IgA (SIgA). Therefore, the determination of the level of SIgA in colostrum and milk of mothers with different lactation levels and mothers at risk at different levels and duration of lactation has a practical interest. Aim. The research aims at studying the dynamics of SIgA content in breast milk, taking into account risk factors and features of lactation. Material and Methods. The content of SIgA in colostrum and breast milk of 372 mothers with full lactation and 208 with hypogalactia, of which 72 with early and 146 with late hypogalactia at different times of lactation (1-8 days and 1-3 months) was determined. The SIgA content was also studied in mothers; 65 with preeclampsia, including 12 with early hypogalactia, 24 with late hypogalactia, 23 with full lactation, and 44 with anemia of pregnancy, including 12 with early hypogalactia, 19 with late hypogalactia and 13 with full lactation. The determination of SIgA content in colostrum and milk was performed using the method of simple radial immunodiffusion in a gel by G. Mancini et al. Results and Discussion. The SIgA concentration in colostrum and breast milk decreased during the secretion process. In early hypogalactia, the content of SIgA did not differ significantly from the level of SIgA in colostrum and breast milk with full lactation in the early neonatal period and at 1-3 months of secretion. In the late hypogalactia, SIgA content did not differ significantly from its level in the control group. Due to the lower amount of milk received by the mother's child with hypogalactia, the supply of children with SIgA is insufficient, and the deficit is higher the sooner the hypogalactia develops. Similar changes in the dynamics of SIgA content have been found in mothers with preeclampsia and at different levels of lactation. The exception was the content of SIgA in colostrum and milk of mothers with anemia of pregnancy and early hypogalactia, which in the first five days of lactation was lower than in mothers with full lactation. Conclusion. The SIgA concentration in colostrum and breast milk decreases during the secretion process. The level of lactation does not affect the dynamics of SIgA content, except for the SIgA content in colostrum and breast milk of mothers with anemia of pregnancy and hypogalactia in the early stages of secretion. Despite the absence of a significant difference in SIgA levels in mothers with different levels of lactation due to less colostrum and milk received by children with early and late hypogalactia, the supply of SIgA is insufficient, and the cumulative deficit is higher the faster the hypogalactia develops.

Maternal dietary intake, nutritional status and macronutrient composition of human breast milk: systematic review

Human breast milk (BM) is the best source of nutrition in early life, particularly during the first 6 months. Nevertheless, human BM composition is variable, and more insight in the exact factors contributing to this variability is warranted. In this review, we explored the impact of maternal dietary intake and nutritional status (e.g. anthropometric measures, BMI, bioimpedance) on human milk macronutrient composition. PubMed, Scopus and Cochrane were systematically searched till November 2019. In total, 4946 publications underwent title-abstract screening; 101 publications underwent full-text screening. Eventually, fifty publications were included in this review, investigating either associations between maternal dietary intake (n 29) and/or maternal nutritional status (n 29), and macronutrient composition of human BM. Reported energy composition ranged from 213 to 301 kJ/100 ml, and 67 % and 54 % of the studies reported associations between with maternal nutritional intake and status, respectively. Protein content ranged from 0·8 to 3·3 g/100 ml, and four studies suggested a negative association with nutritional status. Fat content ranged from 2·1 to 9·8 g/100 ml, and 68 % of the studies reported positive associations with nutritional status. Carbohydrate content ranged from 5·8 to 7·5 g/100 ml, and 67 % of the included studies did not report an association between intake and status. Literature investigating associations of maternal dietary intake and nutrition status with BM composition of macronutrients and energy content is diversified, both in terms of used methodology and results. Further studies using well-defined and standard parameters are essential to aid the formulation of scientific recommendations.

Preservation of Anti-cytomegalovirus Activity in Human Milk Following High-Pressure Processing Compared to Holder Pasteurization

Pasteurized donor human milk is recommended for hospitalized preterm infants when mother’s own milk is unavailable. Our aim was to compare the antiviral activity of human milk processed by Holder pasteurization (HoP) or high-pressure processing (HPP) against representative enveloped and non-enveloped viruses including cytomegalovirus and hepatitis A virus. Expressed milk from 20 donors collected from the Ontario Milk Bank was combined into 10 pools, each from two unique donors. Each pool was processed by HoP (62.5°C, 30 min) or HPP (500 MPa, 8 min, 4°C) and subsequently inoculated with cytomegalovirus or hepatitis A virus to achieve a final concentration of 5-log plaque-forming units/mL. Plaque reduction assays were used to quantify detectable virus after 30 min incubation (room temperature). Post hoc experiments using a 4 h incubation time were conducted if reductions were detected at 30 min. Irrespective of processing, cytomegalovirus concentrations declined in all pools after 30 min incubation (P &lt; 0.0001). Milk processed by HoP exhibited significantly less reduction compared to raw milk (P = 0.0069). In post hoc experiments, anti-cytomegalovirus activity was maintained at 4 h, with high inter-pool variability. Hepatitis A virus concentration remained unchanged after 30 min incubation in raw and processed milk. Anti-cytomegalovirus activity in human milk is preserved following HoP and HPP, persisting up to 4 h post-inoculation; anti-hepatitis A virus activity was not observed in raw or processed milk. Further research is needed to understand how HoP or promising alternative processing methods affect the antiviral activity of donated milk, given its potential importance to recipient infants.

Profile of Twenty-Three Human Milk Oligosaccharides in Han Chinese Mothers throughout Postpartum 1 year

Human milk oligosaccharides (HMOs) are multifunctional carbohydrates in breast milk, which are composed by a variety of structures. This study aimed to identified HMOs concentration profile, milk microbiota composition, and the associations with major maternal characteristics in Han Chinese mothers in the one-year lactation period. Seventeen healthy mothers aged from 28 to 36 years, who gave birth to healthy term infants, were recruited. Carbohydrates were detected using the MIRIS human milk analyzer (HMA), and twenty-three HMOs were quantified using ultra-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS). Results showed that carbohydrates were relatively stable, while total HMO concentrations ranged from 1.74 to 9.72 g/L and decreased gradually over lactation in breast milk. Based on the structure, seven sialylated HMOs concentration showed the significant decline ( $p<0.05$ ) after three months in lactation. In addition, the relationships between maternal factors, containing the lactation period, genetic status, delivery mode, parity, and milk microbiota profile, and the HMO composition in healthy women, which still need further investigations, were observed.

Evaluation of Breast Milk Macronutrient Content in Preeclamptic Mothers

Background: Preeclampsia remains among the leading causes of maternal and perinatal morbidity and mortality worldwide. This study aimed to evaluate the macronutrient content of colostrum in mothers with preeclampsia. Materials and Methods: Women who delivered by cesarean section at ≤37 weeks of gestation were included in the study. Fresh colostrum samples were collected by manual expression on postpartum days 2 and 4 and were analyzed using a mid-infrared human milk analyzer. Demographic characteristics of the patients were recorded. The protein, fat, carbohydrate, and energy composition of the milk samples were compared between mothers with and without preeclampsia. Results: A total of 58 colostrum samples (25 preeclampsia, 33 nonpreeclampsia) were analyzed. The median gestational age of the infants was similar in both groups (32 versus 33 weeks; p > 0.05). There were also no differences between the groups in terms of maternal age, maternal body mass index, maternal weight gain during pregnancy, and infant gender. Median protein, fat, and carbohydrate levels in the colostrum of the preeclamptic mothers were 2.2, 2.1, and 6.3 g/dL, respectively, compared with 1.8, 2.4, and 6.2 g/dL in the nonpreeclamptic mothers, respectively. Although the colostrum of preeclamptic mothers had higher protein content and lower fat content, the difference was not statistically significant. Carbohydrate and energy contents were similar in both groups. Conclusions: The presence of preeclampsia does not cause a significant change in the macronutrient composition of mother's milk. Analyses of micronutrients at different lactation stages in larger samples are needed.

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.

Anti-RBD IgA and IgG Response and Transmission in Breast Milk of Anti-SARS-CoV-2 Vaccinated Mothers

The appearance of the severe acute respiratory syndrome virus-2 (SARS-CoV-2) has had a significant impact on the balance of public health and social life. The data available so far show that newborns and young children do not develop severe forms of COVID-19, but a small proportion of them will still need hospitalization. Even though young children represent an important vector of the infection, vaccination at such a young age was not yet considered. Thus, the question of whether potentially protective antibodies against SARS-CoV-2 could be provided to them via breast milk or across the placenta, as "passive immunity", still stands.

MATERIALS AND METHODS

Between January-July 2021, we have conducted a prospective study that aimed to measure the immunoglobulin (Ig) A and IgG anti-SARS-CoV-2 titers in the breast milk of 28 vaccinated lactating mothers, sampled at 30 and 60 days after the second dose of the anti-SARS-CoV-2 Pfizer or Moderna mRNA vaccines. Anti-RBD reactive IgA and IgG antibodies were detected and quantified by a sandwich enzyme-linked immunosorbent assay.

RESULTS

Anti-RBD IgA and IgG were present in all breast milk samples, both in the first and in the second specimens, without a significant difference between those two. The anti-RBD IgA titers were approximately five-times higher than the anti-RBD IgG ones. The anti-RBD IgA and IgG titers were correlated with the infants' age, but they were not correlated with the vaccine type or mother's age. The anti-RBD IgA excreted in milk were inversely correlated with the parity number.

CONCLUSIONS

Anti-SARS-CoV-2 IgA and IgG can be found in the milk secretion of mothers vaccinated with mRNA vaccines and, presumably, these antibodies should offer protection to the newborn, considering that the antibodies' titers did not decrease after 60 days. The antibody response is directly proportional to the breastfed child's age, but the amount of anti-RBD IgA decreases with the baby's rank. The antibody response did not depend on the vaccine type, or on the mother's age.

Expression profiles of hsa-miR-148a-3p and hsa-miR-125b-5p in human breast milk and infant formulae

Background

Milk-derived microRNAs (miRNAs), including hsa-miR-148a-3p (miR-148a) and hsa-miR-125b-5p (miR-125b), have been shown to be beneficial to the gastrointestinal function in infants. Here, we investigated their expression during lactation in humans and determined whether the infant formulae available in Japan contain these miRNAs.

Methods

Healthy Japanese women (n = 16) who gave birth vaginally or by cesarean section at the Teine Keijinkai Hospital between 1 September 2020, and 31 April 2021 were included in this study. Breast milk was collected by nurses on days 4 or 5 after delivery (hereinafter, transition milk) and on day 30 of postpartum (hereinafter, mature milk). The levels of miR-148a and miR-125b in breastmilk and six commercially available infant formulae were compared and evaluated using quantitative reverse transcription-polymerase chain reaction.

Results

In all participants, the miR-148a level in mature breastmilk was significantly lower than that in the transition milk. The changes in miR-125b expression during lactation showed similar trends to the changes in miR-148a expression. The miR-148a and miR-125b levels in all analyzed infant formulae were lower than 1/500th and 1/100th of those in mature breastmilk, respectively.

Conclusions

The levels of both miR-148a and miR-125b in human breast milk decreased on day 30 postpartum compared with those in the transition milk. Additionally, the expression of these miRNAs in infant formulae available in Japan was very low. Further studies with larger populations are required to understand precisely the lactational changes in the expression of miR148a and miR-125b in breast milk.

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".

Effect of E-cigarettes aerosol exposure during lactation in rats: Hormonal and biochemical aspects

Electronic cigarettes (e-cigarettes) have been marketed as a less lethal substitute for smoking traditional cigarettes. This study aims to investigate the impact of e-cigarettes aerosol exposure on lactating dams and pups, whose dams were exposed. Lactating dams received fresh air (control) or e-cigarettes aerosol during lactation (day 4-21). Maternal exposure to e-cigarettes aerosol during lactation induced significant reduction (P < 0.0001) in the fat content of the milk and serum Leptin level (P < 0.005) compared to control dams. Furthermore, pups whose dams were exposed to e-cigarettes during lactation showed an increased level of glucose, thyroxine and decreased level of insulin. The exposure to e-cigarettes aerosol during lactation altered the composition of milk as well as the hormonal and biochemical profile in dams and pups. This result, if observed in women using e-cigarettes, suggests that e-cigarettes' use during lactation may have consequences on the milk production and hormonal and biochemical profile in breastfeeding mothers and nursing babies.

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.

Perspective: Moving Toward Desirable Linoleic Acid Content in Infant Formula

Infant formula should provide the appropriate nutrients and adequate energy to facilitate healthy infant growth and development. If conclusive data on quantitative nutrient requirements are not available, the composition of human milk (HM) can provide some initial guidance on the infant formula composition. This paper provides a narrative review of the current knowledge, unresolved questions, and future research needs in the area of HM fatty acid (FA) composition, with a particular focus on exploring appropriate intake levels of the essential FA linoleic acid (LA) in infant formula. The paper highlights a clear gap in clinical evidence as to the impact of LA levels in HM or formula on infant outcomes, such as growth, development, and long-term health. The available preclinical information suggests potential disadvantages of high LA intake in the early postnatal period. We recommend performing well-designed clinical intervention trials to create clarity on optimal levels of LA to achieve positive impacts on both short-term growth and development and long-term functional health outcomes.

Determinants of fatty acid content and composition of human milk fed to infants born weighing <1250 g

BACKGROUND

Infants born at very low birth weight (VLBW) are vulnerable to deficits in fatty acids (FAs) but little is known of factors that influence the intakes or composition of their human milk feeds.

OBJECTIVES

We aimed to identify sources of variability in the fat composition of human milk fed to VLBW infants and examine the impact of milk source (mother's own or donor) on fat and FA intakes.

METHODS

Serial samples of mother's milk (n = 476) and donor milk (n = 53) fed to infants born weighing <1250 g (n = 114 infants from 100 mothers) were collected [Optimizing Mothers' Milk for Preterm Infants (OptiMoM) randomized clinical trial]. Fat and FA were analyzed using a mid-infrared human milk analyzer and GC with flame ionization detection.

RESULTS

At full enteral feeding, donor milk is estimated to provide 1.3 g · kg-1 · d-1 less total fat than mature mother's milk (recommended intake: 4.8 g · kg-1 · d-1), and 5-9 mg · kg-1 · d-1 less DHA (22:6n-3) and arachidonic acid (20:4n-6) (estimated average requirement: 55-60 and 35-45 mg · kg-1 · d-1, respectively) than colostrum or transitional milk. Similar deficits were observed in measured intakes of a subset of OptiMoM infants. In multivariable-adjusted models, maternal ethnicity had medium to large [≥0.5 SD score (SDS)] effects on DHA, SFAs, and MUFAs. Mothers with prepregnancy BMI in overweight and obese categories had higher milk total fat (β: 0.35; 95% CI: 0.10, 0.61 and β: 0.46; 95% CI: 0.16, 0.77 SDS, respectively). Those with BMI ≥30 in addition had higher proportions of SFAs (β: 0.61; 95% CI: 0.33, 0.89 SDS) and lower DHA (β: -0.54; 95% CI: -0.89, -0.20 SDS). Other factors, such as gestational age and income, were also associated with FA composition.

CONCLUSIONS

The fat and FA content of human milk fed to VLBW infants is variable. Care must be taken to ensure fat and FA intakes meet recommendations, particularly when feeding a high proportion of donor milk.This trial was registered at clinicaltrials.gov as NCT02137473.

Remodeling of the maternal gut microbiome during pregnancy is shaped by parity

BACKGROUND

The maternal microbiome has emerged as an important factor in gestational health and outcome and is associated with risk of preterm birth and offspring morbidity. Epidemiological evidence also points to successive pregnancies-referred to as maternal parity-as a risk factor for preterm birth, infant mortality, and impaired neonatal growth. Despite the fact that both the maternal microbiome and parity are linked to maternal-infant health, the impact of parity on the microbiome remains largely unexplored, in part due to the challenges of studying parity in humans.

RESULTS

Using synchronized pregnancies and dense longitudinal monitoring of the microbiome in pigs, we describe a microbiome trajectory during pregnancy and determine the extent to which parity modulates this trajectory. We show that the microbiome changes reproducibly during gestation and that this remodeling occurs more rapidly as parity increases. At the time of parturition, parity was linked to the relative abundance of several bacterial species, including Treponema bryantii, Lactobacillus amylovorus, and Lactobacillus reuteri. Strain tracking carried out in 18 maternal-offspring "quadrads"-each consisting of one mother sow and three piglets-linked maternal parity to altered levels of Akkermansia muciniphila, Prevotella stercorea, and Campylobacter coli in the infant gut 10 days after birth.

CONCLUSIONS

Collectively, these results identify parity as an important environmental factor that modulates the gut microbiome during pregnancy and highlight the utility of a swine model for investigating the microbiome in maternal-infant health. In addition, our data show that the impact of parity extends beyond the mother and is associated with alterations in the community of bacteria that colonize the offspring gut early in life. The bacterial species we identified as parity-associated in the mother and offspring have been shown to influence host metabolism in other systems, raising the possibility that such changes may influence host nutrient acquisition or utilization. These findings, taken together with our observation that even subtle differences in parity are associated with microbiome changes, underscore the importance of considering parity in the design and analysis of human microbiome studies during pregnancy and in infants. Video abstract.

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.

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.

The Breast Milk Immunoglobulinome

Breast milk components contribute to the infant’s immune development and protection, and among other immune factors, immunoglobulins (Igs) are the most studied. The presence of IgA in milk has been known for a long time; however, less information is available about the presence of other Igs such as IgM, IgG, and their subtypes (IgG1, IgG2, IgG3, and IgG4) or even IgE or IgD. The total Ig concentration and profile will change during the course of lactation; however, there is a great variability among studies due to several variables that limit establishing a clear pattern. In this context, the aim of this review was firstly to shed light on the Ig concentration in breast milk based on scientific evidence and secondly to study the main factors contributing to such variability. A search strategy provided only 75 studies with the prespecified eligibility criteria. The concentrations and proportions found have been established based on the intrinsic factors of the study—such as the sampling time and quantification technique—as well as participant-dependent factors, such as lifestyle and environment. All these factors contribute to the variability of the immunoglobulinome described in the literature and should be carefully addressed for further well-designed studies and data interpretation.

Daily variation of macronutrient concentrations in mature human milk over 3 weeks

Human milk (HM) composition is known to be highly variable, both between individuals and across the duration of lactation. It is less clear, however, to what extent fat, lactose and protein concentrations in HM change daily over shorter time periods in mature HM, and no studies have evaluated this to date. The aim of this study was to systematically assess and compare HM macronutrient concentrations in samples collected at different times of day, from left and right breasts and daily across a 3-week period in the same woman. Fifteen lactating women (1.6–4.9 months postpartum) collected daily pre-feed HM samples from both breasts each morning for 21 consecutive days and completed intensive sampling once a week (morning, afternoon and evening samples) during this period. Concentrations of fat, protein and lactose in HM did not differ according to time of day, day of week or breast used for collection. The results of this study suggest that pre-feed samples collected at any point across a 3-week period and from either the left or right breast provide comparable measures of fat, protein and lactose concentrations in mature HM, in pragmatic studies where women are collecting their own HM samples.

Clinical trial registration: Australian New Zealand Clinical Trials Registry (ACTRN12619000606189).

What Are the Maternal Factors that Potentially Intervenes in the Nutritional Composition of Human Milk?

Background: To evaluate the potential factors associated with the nutritional composition of human milk of puerperal women. Methods: cross-sectional study, conducted between March 2016 and August 2017, with 107 women, selected in a Tertiary Health Care Tertiary Health Facility of the Unified Health System (SUS) in the Municipality of Rio de Janeiro. Data were collected two months after delivery. The dependent variable of the study was the nutritional composition of human milk. We divided the independent variables into hierarchical levels: distal (age, schooling, parity and pregestational nutritional status), intermediate (number of prenatal visits and gestational weight gain) and proximal (alcohol consumption, smoking, diabetes mellitus and hypertension). For data analysis, we applied the multiple linear regression, centered on the hierarchical model. Only the variables associated with the nutritional composition of breast milk remained in the final model at a 5% level of significance. Results: The nutritional composition of human milk yielded by women with pregestational overweight, smokers and hypertensive had higher amounts of lipids and energy. Conversely, women with gestational weight gain below the recommended had lower amounts of these components. Conclusion: The evaluation of factors associated with the nutritional composition of human milk is extremely important to assist post-partum care practices. In this study, we observed that lipid and energy contents were associated to pregestational nutritional status, gestational weight gain, smoking and hypertension.

Lactation as a programming window for metabolic syndrome

The concept of developmental origins of health and disease (DOHaD) was initially supported by the low birth weight and higher risk of developing cardiovascular disease in adult life, caused by nutrition restriction during foetal development. However, other programming windows have been recognized in the last years, namely lactation, infancy, adolescence and even preconception. Although the concept has been developed in order to study the impact of foetal calorie restriction in adult life, it is now recognized that maternal overweight during programming windows is also harmful to the offspring. This article explores and summarizes the current knowledge about the impact of maternal obesity and obesogenic diets during lactation in the metabolic programming towards the development of metabolic syndrome in the adult life. The impact of maternal obesity and obesogenic diets in milk quality is discussed, including the alterations in specific micro and macronutrients, as well as the impact of such alterations in the development of metabolic syndrome-associated features in the newborn, such as insulin resistance and adiposity. Moreover, the impact of milk quality and formula feeding in infants' gut microbiota, immune system maturation and in the nutrient-sensing mechanisms, namely those related to gut hormones and leptin, are also discussed under the current knowledge.

Impact of maternal obesity and prebiotic supplementation on select maternal milk microRNA levels and correlation with offspring outcomes

Breast milk composition varies with maternal factors including diet and confers health benefits to the neonate; however, the mechanisms mediating this protection remain incompletely understood. Our aim was to investigate the effects of supplementing a maternal high-fat/sucrose (HFS) diet with prebiotic oligofructose (OFS) on milk composition in rats and associations with offspring body composition and gut microbiota. Obese Sprague-Dawley dams consumed a control, HFS, HFS + OFS (10 % wt/wt) or HFS diet weight-matched to the HFS + OFS group (HFS-WM) during pregnancy and lactation. Pups were weaned onto a HFS diet on day 21. Milk was collected at weaning and analysed for protein, leptin and microRNA (miRNA) levels. Milk produced by HFS dams contained less protein than milk from lean controls which was normalised by OFS. Six miRNA (miR-222, miR-203a, miR-200a, miR-26a, miR-27a and miR-103) were differentially expressed in milk according to maternal diet. Milk leptin content was positively correlated with maternal body fat and faecal Enterobacteriaceae in male offspring at 24 weeks of age. Milk protein content was inversely associated with maternal body fat and body weight. miR-200a was positively associated with maternal body fat and Enterobacteriaceae in female offspring at 24 weeks of age. Correlations between milk protein and multiple milk miRNA and offspring body composition and gut microbiota differed by sex. Overall, our results suggest that obesogenic diets and prebiotic supplementation can alter the protein and miRNA levels in breast milk in rats and these milk components may explain, in part, the influence of these maternal diets on offspring body composition.

Acute changes to breast milk composition following consumption of high-fat and high-sugar meals

Breast milk composition is influenced by habitual diet, yet little is known about the short-term effects of changes in maternal diet on breast milk macronutrient concentrations. Our aim was to determine the acute effect of increased consumption of sugar/fat on breast milk protein, lactose and lipids. Exclusively breastfeeding women (n = 9) were provided with a control, higher fat (+28 g fat) and higher sugar (+66 g sugar) diet over three separate days at least 1 week apart. Hourly breast milk samples were collected concurrently for the analysis of triglycerides, cholesterol, protein, and lactose concentrations. Breast milk triglycerides increased significantly following both the higher fat and sugar diet with a greater response to the higher sugar compared to control diet (mean differences of 3.05 g/dL ± 0.39 and 13.8 g/dL ± 0.39 in higher fat and sugar diets, respectively [P < 0.001]). Breast milk cholesterol concentrations increased most in response to the higher sugar diet (0.07 g/dL ± 0.005) compared to the control (0.04 g/dL) and the higher fat diet (0.05 g/dL) P < 0.005. Breast milk triglyceride and lactose concentrations increased (P < 0.001, P = 0.006), whereas protein decreased (p = 0.05) in response to the higher fat diet compared to the control. Independent of diet, there were significant variations in breast milk composition over the day; triglycerides and cholesterol concentrations were higher at end of day (P < 0.001), whereas protein and lactose concentrations peaked at Hour 10 (of 12) (P < 0.001). In conclusion, controlled short-term feeding to increase daily sugar/fat consumption altered breast milk triglycerides, cholesterol, protein and lactose. The variations observed in breast milk protein and lactose across the 12 h period is suggestive of a circadian rhythm.

Human milk composition promotes optimal infant growth, development and health

Human milk is a living dynamic fluid that promotes optimal nutrition and development of the infant and impacts health across the lifespan. This review reports on the diverse range of nutrients, immune protection factors, hormones, microbes and metabolites in human milk and their impacts on infant nutrition and health. While many of these components are stable across lactation and similar between women, some vary over time, and in response to maternal and infant health status, maternal diet and geographic location. Human milk may be considered as personalized nutrition, with many components working synergistically to stimulate and support the infant's immature immune system, while enhancing appropriate development, growth and body composition.