The effect of maternal habitus on macronutrient content of human milk colostrum

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.

Correlation Between Maternal Age and Cytokine (IL-6 and TGF-Beta) Levels in Colostrum

BACKGROUND

Cytokines are small proteins that play an important role in cell signaling, particularly in inflammatory pathways. There are both pro- as well as anti-inflammatory cytokines that regulate this pathway and modulate the immune responses. Advancing maternal age is associated with systemic inflammation. The present study intends to evaluate the effect of advancing maternal age on cytokine (IL-6 and TGF-β) levels in colostrum, the first breast milk secreted by mothers.

METHODOLOGY

A total of 77 term deliveries were enrolled in the study. Colostrum specimens were collected and evaluated for cytokine IL-6 and TGF-β levels. Colostrum IL-6 and TGF-β levels were correlated with maternal age and were assessed using the Spearman rank correlation coefficient. Multivariate analysis was done using a linear regression model comprising age, parity, and mode of delivery.

RESULTS

Mean colostrum IL-6 and TGF-β levels were 113.3±73.1 pg/ml and 20.9±23.6 pg/ml, respectively. No significant correlation between maternal age and colostrum IL-6 levels was observed (r=0.137; p=0.314). However, there was a significant positive correlation between maternal age and colostrum TGF-β levels (r=0.452; p<0.001).

CONCLUSIONS

The findings of the study show a significant association between maternal age and colostrum TGF-β levels. The impact of colostrum cytokine levels on neonatal growth and development in context with advancing maternal age needs to be evaluated.

Carbohydrate content of human milk is affected by seasonal variations: a retrospective observational study

OBJECTIVE

The influence of seasonal variation upon human milk macronutrient content has not been elucidated. This study aimed to compare the macronutrient content of HM produced by lactating mothers during the winter and the summer seasons.

STUDY DESIGN

Macronutrient content of colostrum milk samples collected from lactating mothers of healthy term infants between March 2012 and February 2016 was measured by mid-infrared spectroscopy and compared.

RESULT

The carbohydrate content of the colostrum was significantly higher in the summer season than in the winter season (6.2 ± 1.3 vs. 5.5 ± 1.4, p-value < 0.001). Protein, fat, and energy contents were similar in summer and winter in both groups (protein 2.7 ± 2.1 vs. 2.6 ± 2.2 g/100 ml, fat 2.6 ± 1.9 vs. 2.35 ± 1.9 g/100 ml, and energy 62 ± 19.1 vs. 60.5 ± 21 kcal/100 ml, respectively).

CONCLUSION

The carbohydrate content in colostrum obtained from mothers of term infants was affected by seasonal variations.

Human Milk Lipids Induce Important Metabolic and Epigenetic Changes in Neonates

Lipids are a major source of energy during the fetal/neonatal period. Most are received from the mother, transplacentally during the intrauterine period or via maternal milk after birth. However, in addition to the known nutritional roles, lipids are now known to bind a variety of cellular receptors to regulate specific patterns in metabolism and gene expression. The expression of these receptors is regulated by various genetic and environmental stimuli, and ligation can activate positive-feedback loops in the expression and the activity of downstream signaling pathways. The authors summarize the role of lipid ligands, cognate receptors, epigenetic regulation, and downstream signaling.

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.

Macronutrient Composition of Colostrum in Mothers with Gestational Diabetes Mellitus

Background: Infants fed breast milk are known to have lower rates of childhood obesity. However, there is evidence suggesting an increased risk of obesity in infants who receive milk from a diabetic mother. The aim of this study was to investigate the calorie and macronutrient content of colostrum in mothers with gestational diabetes mellitus (GDM). Methods: This prospective, controlled study included mothers who had diagnosis of GDM and a control group of mothers without GDM who delivered at term. Colostrum samples were analyzed for macronutrients (fat, protein, and carbohydrate) and calorie content using a human milk analyzer (Miris, Uppsala, Sweden). Results: A total of 92 colostrum samples were analyzed, 31 in the GDM group and 61 in the non-GDM group. The carbohydrate content of colostrum in the GDM group was higher compared with the non-GDM group (p = 0.004). The calorie, fat, and protein contents of colostrum were similar between the groups (p > 0.05). Multiple regression analysis indicated that having GDM was significantly related to carbohydrate content. Conclusion: The colostrum of GDM mothers had higher carbohydrate content. This might be one of the factors explaining the relationship between diabetic breast milk and infantile obesity.

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.

Tandem Breastfeeding and Human Milk Macronutrients: A Prospective Observational Study

BACKGROUND

Tandem breastfeeding is defined as two or more offspring of different ages who are breastfed by their mother at the same time. Breastfeeding during pregnancy and tandem breastfeeding have not been widely investigated.

RESEARCH AIM

To determine the influence of tandem breastfeeding on the macronutrient content of human milk.

METHODS

This longitudinal study used a prospective and a retrospective group. Human milk samples from tandem-breastfeeding participants (n = 18) were compared to samples from non-tandem-breastfeeding participants (n = 31). Samples were collected during the last month of pregnancy (pregnancy milk), 72 hr after birth (colostrum) and 14-60 days post-delivery (mature milk). Macronutrients were measured by mid-infrared spectroscopy.

RESULTS

Fat content in pregnancy milk was lower than in mature milk (p < .01). Protein content was higher in pregnancy milk than in colostrum and mature milk (p < .01 and p < .001, respectively). Inversely, carbohydrate content in pregnancy milk was lower than in colostrum and mature milk (p = .02 and p < .01, respectively). Fat and energy contents in pregnancy milk of tandem-breastfeeding participants were lower than in mature milk of non-tandem-breastfeeding participants (p < .001 and p < .01, respectively), and protein content was higher than in mature milk (p < .001). Carbohydrate content in colostrum and mature milk of tandem-breastfeeding participants was higher than that of non-tandem-breastfeeding participants (p < .001 for both).

CONCLUSION

Human milk produced during pregnancy had different macronutrient content than human milk produced after delivery. Colostrum and mature milk of tandem-breastfeeding participants were similar to human milk produced by non-tandem-breastfeeding participants, with the exception of carbohydrate content.

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.

A comprehensive review on non-clinical methods to study transfer of medication into breast milk - A contribution from the ConcePTION project

Breastfeeding plays a major role in the health and wellbeing of mother and infant. However, information on the safety of maternal medication during breastfeeding is lacking for most medications. This leads to discontinuation of either breastfeeding or maternal therapy, although many medications are likely to be safe. Since human lactation studies are costly and challenging, validated non-clinical methods would offer an attractive alternative. This review gives an extensive overview of the non-clinical methods (in vitro, in vivo and in silico) to study the transfer of maternal medication into the human breast milk, and subsequent neonatal systemic exposure. Several in vitro models are available, but model characterization, including quantitative medication transport data across the in vitro blood-milk barrier, remains rather limited. Furthermore, animal in vivo models have been used successfully in the past. However, these models don't always mimic human physiology due to species-specific differences. Several efforts have been made to predict medication transfer into the milk based on physicochemical characteristics. However, the role of transporter proteins and several physiological factors (e.g., variable milk lipid content) are not accounted for by these methods. Physiologically-based pharmacokinetic (PBPK) modelling offers a mechanism-oriented strategy with bio-relevance. Recently, lactation PBPK models have been reported for some medications, showing at least the feasibility and value of PBPK modelling to predict transfer of medication into the human milk. However, reliable data as input for PBPK models is often missing. The iterative development of in vitro, animal in vivo and PBPK modelling methods seems to be a promising approach. Human in vitro models will deliver essential data on the transepithelial transport of medication, whereas the combination of animal in vitro and in vivo methods will deliver information to establish accurate in vitro/in vivo extrapolation (IVIVE) algorithms and mechanistic insights. Such a non-clinical platform will be developed and thoroughly evaluated by the Innovative Medicines Initiative ConcePTION.

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 Maternal Anxiety on Human Milk Macronutrients Content: A Prospective Observational Study

Objective: The impact of maternal anxiety on the macronutrients content of human milk (HM) is unknown. We hypothesized that maternal stress generated by her infant's hospitalization will affect the mother's breast milk's macronutrients content. Materials and Methods: HM samples (2-3 mL) were collected from 21 mothers whose infants were hospitalized for 2-3 days between August 2016 and November 2017 due to neonatal fever. Samples were provided at three time points: first day of admission, second day of admission, and 1 week after discharge. The maternal anxiety level was measured by the State-Trait Anxiety Inventory (STAI). Milk analyses for macronutrients were performed by infrared transmission spectroscopy. Results: Fat and energy contents of HM on day 7 were significantly higher compared with the day of admission (p = 0.019 and p = 0.022, respectively), whereas they were similar to values on day 2. The maternal anxiety level (STAI) at the time of infant admission was significantly higher than at 1 week after discharge (p < 0.001). There was no significant correlation between the changes in fat content and changes in the STAI score between admission and 1 week after discharge. Conclusion: Short infant hospitalization is associated with a significant rise in maternal stress; however, macronutrients content of HM remained unaffected.

Comparison of the Macronutrient Content of Colostrum: Locals with Refugees

Background: Breast milk (BM) is considered the ideal and natural way of feeding for all infants. Although previous studies evaluated the factors influencing the content of BM, data concerning the effect of being a refugee on macronutrient contents of BM are rather inadequate. Therefore, we aimed to compare the macronutrient content of colostrum samples of Turkish and Syrian mothers. Materials and Methods: BM from lactating mothers who delivered term newborns was collected within the first 48 hours of lactation. Milk protein, fat, carbohydrate, and energy levels were measured by using a mid-infrared human milk analyzer. Demographic characteristics of the mothers and the infants were recorded. Results: Colostrum samples of 180 lactating mothers (Turkish: 96, Syrian: 84) were obtained. There were no significant differences between the groups in terms of body mass index of the mothers, mode of delivery, and infant gender. However, Syrian mothers gained less weight during pregnancy compared with Turkish mothers (p = 0.029). The median protein, fat, and energy levels of colostrum samples were found to be significantly higher in Turkish mothers than in Syrian mothers (p = 0.001, p = 0.017, p < 0.001, respectively). Cesarean delivery and being a Syrian refugee were independently associated with lower protein content of colostrum in logistic regression analysis. Conclusion: Lactating mothers who delivered their babies through vaginal route were found to be advantageous in terms of colostral protein content. Also, an association between being a refugee and lower protein content of colostrum was remarkable.

The impact of maternal obesity on human milk macronutrient composition: A systematic review and meta-analysis

Maternal obesity has been associated with changes in the macronutrient concentration of human milk (HM), which have the potential to promote weight gain and increase the long-term risk of obesity in the infant. This article aimed to provide a synthesis of studies evaluating the effects of maternal overweight and obesity on the concentrations of macronutrients in HM. EMBASE, MEDLINE/PubMed, Cochrane Library, Scopus, Web of Science, and ProQuest databases were searched for relevant articles. Two authors conducted screening, data extraction, and quality assessment independently. A total of 31 studies (5078 lactating women) were included in the qualitative synthesis and nine studies (872 lactating women) in the quantitative synthesis. Overall, maternal body mass index (BMI) and adiposity measurements were associated with higher HM fat and lactose concentrations at different stages of lactation, whereas protein concentration in HM did not appear to differ between overweight and/or obese and normal weight women. However, given the considerable variability in the results between studies and low quality of many of the included studies, further research is needed to establish the impact of maternal overweight and obesity on HM composition. This is particularly relevant considering potential implications of higher HM fat concentration on both growth and fat deposition during the first few months of infancy and long-term risk of obesity.

Considerations for Preterm Human Milk Feedings When Caring for Mothers Who Are Overweight or Obese

BACKGROUND

Mother's milk is the recommended source of nutrition for all newborns. Preterm infants may be further compromised by maternal factors that impede successful lactation and alter milk composition.

PURPOSE

To review and summarize the state of the science regarding implications of maternal overweight and obesity on successful lactation and associated alterations in preterm mother's milk composition.

METHODS/SEARCH STRATEGY

PubMed, EMBASE, and Web of Science searches were performed using relevant key words to identify references addressing maternal overweight or obesity, prematurity, human milk, and lactation.

FINDINGS/RESULTS

In the United States, more than half of women enter pregnancy with an overweight or obese body mass index. These women have increased risk of adverse pregnancy outcomes and obstetric complications that can undermine successful initiation and continuation of lactation, including preterm birth. Maternal overweight and obesity are also associated with alterations in mother's milk composition.

IMPLICATIONS FOR PRACTICE

Mother-preterm infant dyads affected by maternal overweight and obesity are at risk for barriers to initiation and continuation of lactation. Support for early initiation of milk expression is needed. Continued support, especially during the first weeks of lactation, can facilitate sustained milk production.

IMPLICATIONS FOR RESEARCH

Considerable knowledge gaps remain in this area of human milk science. Future research is needed to facilitate more comprehensive understanding of differences in milk composition associated with maternal overweight and obesity and their impact on clinical outcomes in the preterm infant.

Maternal body mass index, parity and smoking are associated with human milk macronutrient content after preterm delivery

BACKGROUND

Maternal characteristics may be associated with human milk macronutrients but no definite conclusions have been made to date.

AIM

This study aimed to determine the relationship of maternal-associated factors on the content of macronutrients in human milk for the first six weeks after preterm delivery.

STUDY DESIGN

Prospective observational cohort study.

SUBJECTS

Milk samples were collected from mothers after premature birth between 24 + 0-35 + 6 weeks.

OUTCOME MEASURES

Macronutrients and energy content were analyzed by mid-infrared transmission spectroscopy. Demographic and anthropometric data from mothers were systematically recorded.

RESULTS

A total 1.558 human milk samples from 192 mothers were analyzed. Colostrum: higher protein (p = 0.001) and lower carbohydrate content (p = 0.003) were present in primiparous compared to multiparous milk. Vaginal birth was associated with increased carbohydrate content (p = 0.021). Fat and energy content in colostrum was not related to any maternal characteristics. Mature human milk: similarly to colostrum, higher protein content (p = 0.001) and lower carbohydrates content (p = 0.022) were observed in primiparous compared to multiparous milk. The mode of delivery was found to be another factor possibly influencing protein and carbohydrate levels (p = 0.036, p = 0.003, respectively). Pre-pregnancy obesity was associated with increased fat (p = 0.030) and energy content (p = 0.020) in human milk. On the contrary, smoking had a negative relationship to fat and energy content (p = 0.026, p = 0.007, respectively).

CONCLUSION

Human milk macronutrient concentration after preterm delivery is associated with pre-pregnancy obesity, parity, mode of delivery and smoking. The impact of maternal factors on human milk composition should be taken into account in a strategy of feeding in premature infants.

The effect of gestational diabetes mellitus on human milk macronutrients content

OBJECTIVE

To test the null hypothesis that human milk (HM) macronutrients (fat, lactose, protein) and caloric content in women with gestational diabetes mellitus (GDM) is similar to that of women without GDM.

STUDY DESIGN

Sixty-two lactating mothers (31 GDM, 31 no-GDM) were studied after confirmation by 100-g oral glucose tolerance test. Each mother contributed three manually expressed HM samples (within 72 h after labor (colostrum), after 7 days (transitional) and at 14 days (mature)). Analysis was done by infrared transmission spectroscopy.

RESULTS

Non-GDM and GDM groups did not differ by maternal age, pre-pregnancy weight, height, diet, pregnancy weight gain, gestational age, and infant birth weight. Macronutrients content in colostrum and transitional milk did not differ between groups. Fat and energy contents in mature HM were higher in non-GDM samples than in GDM samples (p = 0.07 and p < 0.02, respectively).

CONCLUSION

Fat and energy content of mature HM obtained from mothers with GDM is lower compared to that of mature HM from mothers without GDM.

Breast Milk Macronutrient Components in Prolonged Lactation

Human milk (HM) is the first dietary exposure in infancy and the best nutritional option for growth and healthy development of the newborn and infant. The concentrations of macronutrients, namely proteins, carbohydrates and lipids, change during lactation stages. HM has been studied extensively in the first 6 months of lactation, but there are limited data regarding milk composition beyond 1 or 2 years postpartum. The aim of our study was to describe longitudinal changes in HM macronutrient concentrations during the prolonged lactation of healthy mothers from the 1st to the 48th month. For the macronutrient content of milk of mothers breastfeeding for longer than 18 months, fat and protein increased and carbohydrates decreased significantly, compared with milk expressed by women breastfeeding up to 12 months. Moreover, the concentration of fat, protein and carbohydrates in HM over 2 years of lactation from the 24th to the 48th month remained at a stable level. However, analyzed macronutrients were positively (carbohydrate, r = 0.51) or negatively (fat, r = -0.36 and protein, r = -0.58) correlated with the amount of feeding. Our results create a greater potential for understanding the nutritional contribution of HM over 2 years of lactation and showed that the source of calories in breast milk for older children is mainly fat, while carbohydrates play a greater role in infant nutrition in the early stage. The observed changes of macronutrient concentrations from the 1st to the 48th month of lactation are probably related to the adaptation of milk composition to the increased energy demand of the intensively growing child.