Human milk cortisol is associated with infant temperament

Ramadan fasting in the third trimester of pregnancy and postpartum colostrum cortisol concentrations in Morocco

Breast milk cortisol concentration varies among and within lactating women, but the causes and consequences of variation are not yet fully understood. This study investigated whether maternal fasting from food and water for over 16 h per day during the third trimester of pregnancy was associated with increased concentrations of cortisol in colostrum during the month of Ramadan in a Moroccan sample. Participants were women who gave birth at the public maternity hospital in Rabat, Morocco throughout the month of and month following Ramadan. Participants completed interviews (N = 92), underwent anthropometric assessment (N = 73), and colostrum samples (N = 63) were collected approximately 48-72 h postpartum. Cortisol analysis was completed on a subset of colostrum samples (N = 43). Women were categorized as fasting every day of Ramadan before giving birth (N = 52/92, 57%), fasting some days (N = 29/92, 32%), and not fasting (N = 11/92, 11%). For women who fasted, average fasting duration was 19.5 days (range: 1-29 days), and average time between the last day of fasting and birth was 8.8 days (range: 0-43 days). The number of days of fasting was positively associated with cortisol concentrations in colostrum (p < .009) in a multivariate analysis controlling for maternal anthropometry, hypertension and/or diabetes, and reasons for opting out of fasting. Each day of fasting was associated with a 4.05% increase in colostrum cortisol. Results are consistent with the hypothesis that maternal fasting during the third trimester of pregnancy increases breast milk cortisol and thus alters the hormonal milieu to which the infant is exposed.

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

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

Association between Maternal Perinatal Stress and Depression on Infant DNA Methylation in the First Year of Life

Maternal stress and depression during pregnancy and the first year of the infant's life affect a large percentage of mothers. Maternal stress and depression have been associated with adverse fetal and childhood outcomes as well as differential child DNA methylation (DNAm). However, the biological mechanisms connecting maternal stress and depression to poor health outcomes in children are still largely unknown. Here we aim to determine whether prenatal stress and depression are associated with changes in cord blood mononuclear cell DNAm (CBMC-DNAm) in newborns (n = 119) and whether postnatal stress and depression are associated with changes in peripheral blood mononuclear cell DNAm (PBMC-DNAm) in children of 12 months of age (n = 113) from the Canadian Healthy Infant Longitudinal Development (CHILD) cohort. Stress was measured using the 10-item Perceived Stress Scale (PSS) and depression was measured using the Center for Epidemiologic Studies Depression Questionnaire (CESD). Both stress and depression were measured at 18 weeks and 36 weeks of pregnancy and six months and 12 months postpartum. We conducted epigenome-wide association studies (EWAS) using robust linear regression followed by a sensitivity analysis in which we bias-adjusted for inflation and unmeasured confounding using the bacon and cate methods. To investigate the cumulative effect of maternal stress and depression, we created composite prenatal and postnatal adversity scores. We identified a significant association between prenatal stress and differential CBMC-DNAm at 8 CpG sites and between prenatal depression and differential CBMC-DNAm at 2 CpG sites. Additionally, we identified a significant association between postnatal stress and differential PBMC-DNAm at 8 CpG sites and between postnatal depression and differential PBMC-DNAm at 11 CpG sites. Using our composite scores, we further identified 2 CpG sites significantly associated with prenatal adversity and 7 CpG sites significantly associated with postnatal adversity. Several of the associated genes, including PLAGL1, HYMAI, BRD2, and ERC2 have been implicated in adverse fetal outcomes and neuropsychiatric disorders. This suggested that differential DNAm may play a role in the relationship between maternal mental health and child health.

Association between maternal stress and premature milk cortisol, milk IgA, and infant health: a cohort study

Background

Maternal stress is pervasive in the neonatal intensive care unit (NICU). Maternal stress is associated with changes in human milk (HM) immunomodulatory agents, which may impact neonatal health. We sought to determine the association between maternal stress, HM immunoglobulin A (IgA) and cortisol, and to assess how these milk components correlate with infant immune and neurodevelopmental outcomes. We then compared how these associations persist over time.

Methods

The study design involved a cohort study of exclusively breastfeeding mothers and their singleton moderately preterm (28-34 weeks) infants admitted to the NICU. We collected maternal serum, maternal saliva, and first-morning whole milk samples, and administered maternal stress questionnaires at 1 and 5 weeks postpartum. We analyzed the samples for HM IgA (using a customized immunoassay in skim milk) and for HM and salivary cortisol (using a chemiluminescent immunoassay). Infant illness was assessed using the Score for Neonatal Acute Physiology II (SNAP II) and SNAP II with Perinatal Extension (SNAPPE II), and infant neurodevelopment were assessed using the Test of Infant Motor Performance. We analyzed changes in HM IgA and cortisol over time using paired t-tests. Furthermore, we performed correlation and regression analyses after adjusting for gestational age (GA), corrected GA, and infant days of life.

Results

In our study, we enrolled 26 dyads, with a mean maternal age of 28.1 years, consisting of 69% white, 19% Black, and 8% Hispanic. Cortisol: Salivary and HM cortisol were closely associated in week 1 but not in week 5. Though mean salivary cortisol remained stable over time [2.41 ng/mL (SD 2.43) to 2.32 (SD 1.77), p = 0.17], mean HM cortisol increased [1.96 ng/mL (SD 1.93) to 5.93 ng/mL (SD 3.83), p < 0.001]. Stress measures were inversely associated with HM cortisol at week 1 but not at week 5. IgA: HM IgA decreased over time (mean = -0.14 mg/mL, SD 0.53, p < 0.0001). High maternal stress, as measured by the Parental Stressor Scale: neonatal intensive care unit (PSS:NICU), was positively associated with HM IgA at week 5 (r = 0.79, P ≤ 0.001). Higher IgA was associated with a lower (better) SNAP II score at week 1 (r = -0.74, p = 0.05). No associations were found between maternal stress, salivary cortisol, HM cortisol, or HM IgA and neurodevelopment at discharge (as assessed using the TIMP score). Furthermore, these relationships did not differ by infant sex.

Conclusion

Maternal stress showed associations with HM cortisol and HM IgA. In turn, HM IgA was associated with lower measures of infant illness.

Perinatal hair cortisol concentrations linked to psychological distress and unpredicted birth complications

Maternal well-being and stress during the perinatal period have been hypothesized to influence birth outcomes and the postnatal development of offspring. In the present study, we explored whether hair cortisol concentration (HCC) was related to symptoms of psychological distress during the perinatal period and with unpredicted birth complications (UBCs). Surveys measuring symptoms of perceived stress, state/trait anxiety, and depression were collected from 53 participants (mean age = 31.1, SD = 4.04; 83% Caucasian, 17% other races) during the third trimester and again at two and six months after birth, 24.5% of which reported UBCs. In a subset of participants, we measured HCC in hair samples collected during the third trimester (27-39 weeks) and six months after birth. Compared to participants reporting normal births, those reporting UBCs had significantly elevated composite stress, anxiety, and depression (SAD) scores two months after birth, but scores decreased by six months postpartum. During the third trimester, HCC was positively associated with reported SAD scores, and HCC was elevated in participants reporting birth complications. Logistic regression showed HCC, but not SAD scores, predicted UBCs (p = 0.023, pseudo R2= 19.7%). Repeated measures MANOVA showed HCC varied over the perinatal period depending on both SAD scores reported at two months postpartum and the experience of UBCs; but when SAD scores reported at six months postpartum were included in the model, the association between HCC and SAD scores and the influence of UBCs was diminished. Although generalizability is limited by our relatively small, homogeneous sample, findings support a positive association between reported psychological distress and HCC during pregnancy and at two months postpartum. We also report a novel finding that chronically elevated cortisol concentrations during pregnancy were related to the risk of UBCs and remain elevated through the early postpartum period, suggesting the importance of monitoring both psychological distress and HCC during the perinatal period.

Mothers' prenatal distress accelerates adrenal pubertal development in daughters

Human life history schedules vary, partly, because of adaptive, plastic responses to early-life conditions. Little is known about how prenatal conditions relate to puberty timing. We hypothesized that fetal exposure to adversity may induce an adaptive response in offspring maturational tempo. In a longitudinal study of 253 mother-child dyads followed for 15 years, we investigated if fetal exposure to maternal psychological distress related to children's adrenarche and gonadarche schedules, assessed by maternal and child report and by dehydroepiandrosterone sulfate (DHEA-S), testosterone, and estradiol levels. We found fetal exposure to elevated maternal prenatal psychological distress predicted earlier adrenarche and higher DHEA-S levels in girls, especially first-born girls, and that associations remained after covarying indices of postnatal adversity. No associations were observed for boys or for gonadarche in girls. Adrenarche orchestrates the social-behavioral transition from juvenility to adulthood; therefore, significant findings for adrenarche, but not gonadarche, suggest that prenatal maternal distress instigates an adaptive strategy in which daughters have earlier social-behavioral maturation. The stronger effect in first-borns suggests that, in adverse conditions, it is in the mother's adaptive interest for her daughter to hasten social maturation, but not necessarily sexual maturation, because it would prolong the duration of the daughter allomothering younger siblings. We postulate a novel evolutionary framework that human mothers may calibrate the timing of first-born daughters' maturation in a way that optimizes their own reproductive success.

Predictors of milk cortisol in North American women

OBJECTIVES

Human milk content varies across mother-child dyads, environments, and populations. Among the hormones in milk is cortisol, a glucocorticoid; its impact on the breastfeeding child is unknown. Milk cortisol may constitute a signal to the child's developing physiology which can shape characteristics (e.g., growth, temperament) to prevailing environmental conditions. This exploratory study evaluated the maternal, breastfeeding, and infant characteristics associated with milk cortisol.

METHODS

We evaluated archived milk specimens for cortisol using enzyme immunoassay and employed an information-theoretic approach to assess associations between milk cortisol and participant characteristics with linear regression modeling. Because we employed secondary data, information for some variables likely to impact milk cortisol variation (e.g., time of day, socioeconomic status, maternal or infant body mass index, milk energy density) was unavailable.

RESULTS

Participants were 48 lactating mothers from upstate New York, aged 21-40 years. Milk cortisol ranged from 0.098 to 1.007 μg/dL. Child age ranged from 1 to 26 months. In linear regression employing best fit modeling criteria, milk cortisol increased with child age (B: 0.069; p: .000; a 7.1% increase in milk cortisol for each month of child age), while child symptoms of illness (B: -0.398; p: .057; a 33% decrease) and consumption of complementary foods (B: -.525; p: .020; a 41% decrease) were associated with lower milk cortisol.

CONCLUSIONS

We speculate that increasing milk cortisol with child age plays a role in signaling development (e.g., as increasing independence increases risk for injury and other negative health outcomes), independent of the maternal stressors we could capture.

Associations between milk cortisol and activity of the immune system of milk

OBJECTIVES

Both the immune system of human milk and milk cortisol have complex short- and long-term effects on child health and development. As understanding continues to grow of the independent effects of each of these components of milk, it is also important to investigate their intersection, including how milk cortisol affects the immune system of milk. We began this important endeavor through secondary analyses of archived milk specimens.

METHODS

Participants were 31 lactating mothers from upstate New York. We estimated milk cortisol concentrations via enzyme immunoassay. We assessed milk proinflammatory cytokine (interleukin-6, IL-6) responses to pathogenic (Salmonella) and commensal (Escherichia, Lactobacillus, Bifidobacterium) bacteria via in vitro stimulation. We estimated ordered logistic regression models to assess associations between milk cortisol and IL-6 responses to bacteria.

RESULTS

Milk cortisol ranged from 0.098 to 1.007 μg/dL. Milk cortisol was positively associated with IL-6 responses to S. enterica (B: 4.035; 95% CI: 0.674, 7.395) and B. breve (B: 3.675; 95% CI: 0.426, 6.924); this association persisted after controlling for child age. Results were less clear for associations between milk cortisol and IL-6 responses to L. acidophilus (B: 2.318; 95% CI: -1.224, 5.859) and E. coli (B: 2.366; 95% CI: -0.960, 5.692).

CONCLUSIONS

Complex interactions between cortisol and the immune system extend to milk. Milk cortisol was positively associated with proinflammatory responses to some bacteria in vitro. This may suggest that milk cortisol is causally upstream of protective immune activity.

Determinants of maternal breast milk cortisol increase: Examining dispositional and situational factors

BACKGROUND

Breast milk is a rich nutritional source, containing numerous proteins, carbohydrates, and hormones that impact long-term offspring development. Strikingly, predictors and correlates of breast milk composition remain largely unknown. Building on a previously discovered increase in breast milk cortisol concentration from 2 to 12 weeks postpartum, we investigated potential predictors of maternal breast milk cortisol in the first three months post-delivery by examining a suite of maternal dispositional (e.g., attachment, adverse childhood experiences or ACEs) and situational factors (e.g., partner support, self-efficacy).

METHODS

Data from 73 mothers were collected prenatally, at birth, and 2-, 6- and 12 weeks postpartum. The analyses, which sought to predict postnatal changes in breast milk cortisol, included a pool of theoretically-sound constructs (Table 1) and an exploratory data-driven approach. We fit models differing in complexity as preregistered: 1) Random Forest models, capable of modeling interactions and non-linear relationships, and 2) Bayesian linear models, allowing to model change over time while less prone to overfitting.

RESULTS

Overall, we found that no single variable had strong predictive value beyond the known predictors of cortisol, such as time since awakening and time of collection. However, results from both models suggest that ACEs carry information that warrants future investigations, pointing towards a negative relationship with cortisol concentration in breast milk, albeit with a minimal effect size.

CONCLUSION

Using sophisticated models, we found that early life stress may play a role in physiological stress markers in breast milk in the first three months postpartum, with potential implications for offspring development.

The contributions of parental lactation on offspring development: It's not udder nonsense!

The Developmental Origins of Health and Disease (DOHaD) hypothesis describes how maternal stress exposures experienced during critical periods of perinatal life are linked to altered developmental trajectories in offspring. Perinatal stress also induces changes in lactogenesis, milk volume, maternal care, and the nutritive and non-nutritive components of milk, affecting short and long-term developmental outcomes in offspring. For instance, selective early life stressors shape the contents of milk, including macro/micronutrients, immune components, microbiota, enzymes, hormones, milk-derived extracellular vesicles, and milk microRNAs. In this review, we highlight the contributions of parental lactation to offspring development by examining changes in the composition of breast milk in response to three well-characterized maternal stressors: nutritive stress, immune stress, and psychological stress. We discuss recent findings in human, animal, and in vitro models, their clinical relevance, study limitations, and potential therapeutic significance to improving human health and infant survival. We also discuss the benefits of enrichment methods and support tools that can be used to improve milk quality and volume as well as related developmental outcomes in offspring. Lastly, we use evidence-based primary literature to convey that even though select maternal stressors may modulate lactation biology (by influencing milk composition) depending on the severity and length of exposure, exclusive and/or prolonged milk feeding may attenuate the negative in utero effects of early life stressors and promote healthy developmental trajectories. Overall, scientific evidence supports lactation to be protective against nutritive and immune stressors, but the benefits of lactation in response to psychological stressors need further investigation.

Acute decrease in mothers' cortisol following nursing and milk expression

The glucocorticoid hormone cortisol is an integral component of signaling pathways related to stress reactivity, energy balance, immune function, and other processes. In animal models, lactation is robustly associated with alterations in glucocorticoid signaling, and limited data suggest that similar changes may occur across human lactation. We asked whether milk letdown/secretion in breastfeeding mothers was associated with changes in cortisol, and whether such effects required presence of an infant. We measured changes in maternal salivary cortisol concentrations before and after nursing, the expression of breastmilk with an electric pump, or control activities. Participants conducted pre-session and post-session sampling (at 30 min) for all conditions, and provided a sample of pumped milk from one session. Both nursing and mechanical expression of breastmilk but not control were associated with equivalent declines in maternal cortisol concentration from pre-session values, indicating an effect of milk letdown on circulating cortisol independent of infant contact. Pre-session maternal salivary cortisol concentration was strongly and positively correlated with cortisol concentration in pumped milk samples, indicating that cortisol ingested by offspring provides a signal of maternal cortisol levels. Self-reported maternal stress was associated with higher pre-session cortisol concentrations, as well as with a larger drop in cortisol following nursing or pumping. These findings demonstrate that milk release-in the presence or absence of a suckling infant-regulates cortisol in mothers, and supports the potential for maternal signaling through breastmilk.

Ecologies, synergies, and biological systems shaping human milk composition-a report from "Breastmilk Ecology: Genesis of Infant Nutrition (BEGIN)" Working Group 2

Human milk is universally recognized as the preferred food for infants during the first 6 mo of life because it provides not only essential and conditionally essential nutrients in necessary amounts but also other biologically active components that are instrumental in protecting, communicating important information to support, and promoting optimal development and growth in infants. Despite decades of research, however, the multifaceted impacts of human milk consumption on infant health are far from understood on a biological or physiological basis. Reasons for this lack of comprehensive knowledge of human milk functions are numerous, including the fact that milk components tend to be studied in isolation, although there is reason to believe that they interact. In addition, milk composition can vary greatly within an individual as well as within and among populations. The objective of this working group within the Breastmilk Ecology: Genesis of Infant Nutrition (BEGIN) Project was to provide an overview of human milk composition, factors impacting its variation, and how its components may function to coordinately nourish, protect, and communicate complex information to the recipient infant. Moreover, we discuss the ways whereby milk components might interact such that the benefits of an intact milk matrix are greater than the sum of its parts. We then apply several examples to illustrate how milk is better thought of as a biological system rather than a more simplistic "mixture" of independent components to synergistically support optimal infant health.

Pandemic beyond the virus: maternal COVID-related postnatal stress is associated with infant temperament

BACKGROUND

Studies have shown that infant temperament varies with maternal psychosocial factors, in utero illness, and environmental stressors. We predicted that the pandemic would shape infant temperament through maternal SARS-CoV-2 infection during pregnancy and/or maternal postnatal stress. To test this, we examined associations among infant temperament, maternal prenatal SARS-CoV-2 infection, maternal postnatal stress, and postnatal COVID-related life disruptions.

METHODS

We tested 63 mother-infant dyads with prenatal maternal SARS-CoV-2 infections and a comparable group of 110 dyads without infections. To assess postnatal maternal stress, mothers completed the Perceived Stress Scale 4 months postpartum and an evaluation of COVID-related stress and life disruptions 6 months postpartum. Mothers reported on infant temperament when infants were 6-months-old using the Infant Behavior Questionnaire-Revised (IBQ-R) Very Short Form.

RESULTS

Maternal SARS-CoV-2 infection during pregnancy was not associated with infant temperament or maternal postnatal stress. Mothers with higher self-reported postnatal stress rated their infants lower on the Positive Affectivity/Surgency and Orienting/Regulation IBQ-R subscales. Mothers who reported greater COVID-related life disruptions rated their infants higher on the Negative Emotionality IBQ-R subscale.

CONCLUSIONS

Despite no effect of prenatal maternal SARS-CoV-2 infection, stress and life disruptions incurred by the COVID-19 pandemic were associated with infant temperament at 6-months.

IMPACT

SARS-CoV-2 infection during pregnancy is not associated with postnatal ratings of COVID-related life disruptions, maternal stress, or infant temperament. Postnatal ratings of maternal stress during the COVID-19 pandemic are associated with normative variation in maternal report of infant temperament at 6 months of age. Higher postnatal ratings of maternal stress are associated with lower scores on infant Positive Affectivity/Surgency and Orienting/Regulation at 6 months of age. Higher postnatal ratings of COVID-related life disruptions are associated with higher scores on infant Negative Emotionality at 6 months of age.

Factors Influencing Cortisol Concentrations in Breastmilk and Its Associations with Breastmilk Composition and Infant Development in the First Six Months of Lactation

Previous studies provided contradictory results regarding the influence of maternal, seasonal, and infant factors on breastmilk cortisol, and its associations with breastmilk composition and infant development. This study aimed to assess breastmilk cortisol levels at the first, third, and sixth months of lactation and evaluate the associations with maternal psychosocial, seasonal, and infant factors, breastmilk composition, and infant anthropometric and psychomotor development and temperament. Cortisol concentrations were assessed by ELISA in 24 h breastmilk samples obtained from 38 healthy mothers. Maternal psychological status was assessed by EPDS and PSS-10 and infant psychomotor development was assessed using the Children's Development Scale (DSR). Breastmilk cortisol was 11.2 ± 6.2, 11.2 ± 4.3, and 12.7 ± 6.2 ng/mL at the first, third, and sixth months of lactation (p > 0.05), respectively. In the spring-summer season, we observed lower and higher levels of cortisol in the first and sixth months of lactation (p ≤ 0.05), respectively, but no other associations were detected regarding maternal or infant characteristics. In the third month of lactation, cortisol was related to breastmilk crude protein (β = 0.318, 0.007-0.630) and infant BMI z-score before adjustment for infant birthweight and sex (Model 2: β = 0.359, 0.021-0.697), but no other associations with breastmilk composition, infant development, or temperament were confirmed. Our results indicated that breastmilk cortisol is unrelated to maternal and infant factors and has limited influence on breastmilk crude protein, but not on infant anthropometric and psychomotor development.

Minimally invasive biomarkers in human and non-human primate evolutionary biology: Tools for understanding variation and adaptation

BACKGROUND

The use of minimally invasive biomarkers (MIBs - physiological biomarkers obtained from minimally invasive sample types) has expanded rapidly in science and medicine over the past several decades. The MIB approach is a methodological strength in the field of human and non-human primate evolutionary biology (HEB). Among humans and our closest relatives, MIBs provide unique opportunities to document phenotypic variation and to operationalize evolutionary hypotheses.

AIMS

This paper overviews the use of MIBs in HEB. Our objectives are to (1) highlight key research topics which successfully implement MIBs, (2) identify promising yet under-investigated areas of MIB application, and (3) discuss current challenges in MIB research, with suggestions for advancing the field.

DISCUSSION AND CONCLUSIONS

A range of MIBs are used to investigate focal topics in HEB, including energetics and life history variation/evolution, developmental plasticity, and social status and dominance relationships. Nonetheless, we identify gaps in existing MIB research on traits such as physical growth and gut function that are central to the field. Several challenges remain for HEB research using MIBs, including the need for additional biomarkers and methods of assessment, robust validations, and approaches that are standardized across labs and research groups. Importantly, researchers must provide better support for adaptation and fitness effects in hypothesis testing (e.g., by obtaining complementary measures of energy expenditure, demonstrating redundancy of function, and performing lifetime/longitudinal analyses). We point to continued progress in the use of MIBs in HEB to better understand the past, present, and future of humans and our closest primate relatives.

Glucocorticoids in preterm human milk

Background

Glucocorticoids (GCs), cortisol and cortisone, are essential regulators of many physiological responses, including immunity, stress and mammary gland function. GCs are present in human milk (HM), but whether maternal and infant factors are associated with HM GC concentration following preterm birth is unclear.

Materials and methods

HM samples were collected on postnatal day 5 and 10 and at 4 months’ corrected age (4m CA) in a cohort of moderate- and late-preterm infants. GCs in HM were measured by liquid chromatography-tandem mass spectrometry. Relationships between GCs in HM and both maternal and infant characteristics were investigated using Spearman’s correlations and linear mixed models.

Results

170 mothers of 191 infants provided 354 HM samples. Cortisol concentrations in HM increased from postnatal day 5–4m CA (mean difference [MD] 0.6 ± 0.1 ng/ml, p < 0.001). Cortisone concentration did not change across lactation but was higher than cortisol throughout. Compared to no antenatal corticosteroid (ANS), a complete course of ANS was associated with lower GC concentrations in HM through to 4m CA (cortisol: MD –0.3 ± 0.1 ng/ml, p < 0.01; cortisone MD –1.8 ± 0.4 ng/ml, p < 0.001). At 4m CA, higher maternal perceived stress was negatively associated with GC concentrations in HM (cortisol adjusted beta-coefficient [aβ] –0.01 ± 0.01 ng/ml, p = 0.05; and cortisone aβ –0.1 ± 0.03 ng/ml, p = 0.01), whereas higher postpartum depression and maternal obesity were associated with lower cortisone concentrations (aβ –0.1 ± 0.04 ng/ml p < 0.05; MD [healthy versus obese] –0.1 ± 0.04 ng/ml p < 0.05, respectively). There was a weak positive correlation between GC concentrations in HM and gestational age at birth (r = 0.1, p < 0.05). Infant birth head circumference z-score was negatively associated with cortisol concentrations (aβ –0.01 ± 0.04 ng/ml, p < 0.05). At hospital discharge, fat-free mass showed a weak positive correlation with cortisol concentrations (r = 0.2, p = 0.03), while fat mass showed a weak negative correlation with cortisone concentrations (r = –0.25, p < 0.001).

Conclusion

The mammary gland appears to protect the infant from cortisol through inactivation into cortisone. Maternal and infant characteristics were associated with concentration of GCs in HM, including ANS, stress and depression scores, obesity, gestational age and infant size. The effects of HM glucocorticoids on long-term health outcomes requires further research.

Non-nutritive bioactive components in maternal milk and offspring development: a scoping review

Lactation is a critical time in mammalian development, where maternal factors shape offspring outcomes. In this scoping review, we discuss current literature concerning maternal factors that influence lactation biology and highlight important associations between changes in milk composition and offspring outcomes. Specifically, we explore maternal nutritional, psychosocial, and environmental exposures that influence non-nutritive bioactive components in milk and their links to offspring growth, development, metabolic, and behavioral outcomes. A comprehensive literature search was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Extension for Scoping Reviews (PRISMA-ScR) guidelines. Predetermined eligibility criteria were used to analyze 3,275 papers, and the final review included 40 primary research articles. Outcomes of this review identify maternal obesity to be a leading maternal factor influencing the non-nutritive bioactive composition of milk with notable links to offspring outcomes. Offspring growth and development are the most common modes of programming associated with changes in non-nutritive milk composition due to maternal factors in early life. In addition to discussing studies investigating these key associations, we also identify knowledge gaps in the current literature and suggest opportunities and considerations for future studies.

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.

Inheritance of hormonal stress response and temperament in infant rhesus macaques (Macaca Mulatta): Nonadditive and sex-specific effects

OBJECTIVE

Early life interindividual variation in hypothalamic-pituitary-adrenal (HPA) reactivity to stress is predictive of later life psychological and physical well-being, including the development of many pathological syndromes that are often sex-biased. A complex and interactive set of environmental and genetic causes for such variation has been implicated by previous studies, though little attention has been paid to nonadditive effects (e.g. dominance, X-linked) or sex-specific genetic effects.

METHOD

We used a large pedigreed sample of captive 3-4 months old infant rhesus macaques (N = 2,661, 54% female) to fit univariate and multivariate linear mixed quantitative genetic models for four longitudinal blood cortisol samples and three reliable ratings of infant temperament (nervousness, gentleness, confidence) during a mother-infant separation protocol.

RESULTS

Each trait had a moderate narrow-sense heritability (h², 0.26-0.46), but dominance effects caused the first two cortisol samples to have much larger broad-sense heritabilities (H², 0.57 and 0.77). We found no evidence for X-linked variance or common maternal environment variance. There was a sex difference in heritability of the first cortisol sample (h_f² < h_m²), suggesting differing genetic architecture of perception of maternal separation and relocation during infancy. Otherwise, genetic covariance matrices for the sexes were very similar. Genetic correlations between cortisol levels and temperament were weak (< |0.4|) but stronger than residual or phenotypic correlations.

CONCLUSIONS

HPA reactivity and temperament had a primarily additive genetic basis in infant macaques, but there were important complexities to the genetic architecture of including genetic dominance and sex differences in heritability at this early life stage. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Effect of pasteurization on melatonin concentration in human breast milk

Introduction

Women who have problems with lactation can use human milk banks. Mainly this human milk is provided to premature babies and sick newborns. Human milk is the most suitable food for newborns and infants, recommended by WHO (World Health Organization). Human milk has anti-inflammatory, anti-infective, and anti-allergic properties, and also works for immunomodulation. Melatonin has a special, underestimated importance in the composition of breast milk. It is a hormone that has many body functions and, for several decades, its antioxidant potential has been increasingly talked about.

The aim of the study was to examine the effect of Holder pasteurization on melatonin concentration in human milk.

Materials and Methods

18 samples of human milk from donors from the human milk bank were used for the analysis. Melatonin concentration before and after pasteurization was determined by ELISA. In addition, the nutritional content composition of milk was analyzed using MIRIS Human Milk Analyzer and correlations examined.

Results

Melatonin concentration in human milk before pasteurization was 0.65–26.24 pg/mL (Me=9.58, IQR=12.72), while after pasteurization 0.80–29.58 pg/mL (Me=9.98, IQR=11.26). There was a positive correlation between melatonin concentration before and after pasteurization (r=0.797, p<0.001).

Conclusions

The Holder pasteurization process does not affect the concentration of melatonin in milk samples, which may be a recommendation for human milk banks.

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".

DHA Supplementation of Obese Rats throughout Pregnancy and Lactation Modifies Milk Composition and Anxiety Behavior of Offspring

We investigated if supplementing obese mothers (MO) with docosahexaenoic acid (DHA) improves milk long-chain polyunsaturated fatty acid (LCPUFA) composition and offspring anxiety behavior. From weaning throughout pregnancy and lactation, female Wistar rats ate chow (C) or a high-fat diet (MO). One month before mating and through lactation, half the mothers received 400 mg DHA kg⁻¹ d⁻¹ orally (C+DHA or MO+DHA). Offspring ate C after weaning. Maternal weight, total body fat, milk hormones, and milk nutrient composition were determined. Pups’ milk nutrient intake was evaluated, and behavioral anxiety tests were conducted. MO exhibited increased weight and total fat, and higher milk corticosterone, leptin, linoleic, and arachidonic acid (AA) concentrations, and less DHA content. MO male and female offspring had higher ω-6/ ω-3 milk consumption ratios. In the elevated plus maze, female but not male MO offspring exhibited more anxiety. MO+DHA mothers exhibited lower weight, total fat, milk leptin, and AA concentrations, and enhanced milk DHA. MO+DHA offspring had a lower ω-6/ω-3 milk intake ratio and reduced anxiety vs. MO. DHA content was greater in C+DHA milk vs. C. Supplementing MO mothers with DHA improves milk composition, especially LCPUFA content and ω-6/ω-3 ratio reducing offspring anxiety in a sex-dependent manner.

Breast may not always be best: moderation of effects of postnatal depression by breastfeeding and infant sex

BACKGROUND

There is good evidence that female infants are particularly vulnerable to poor emotional outcomes following in utero glucocorticoid exposure. It is currently unclear whether such effects might persist into the postnatal period for breastfed infants, as maternal cortisol is expressed in breastmilk and is influenced by maternal psychological distress. We pre-registered hypotheses that maternal postnatal depression would be associated with infant negative emotionality, and that this effect would be moderated by breastfeeding status and infant sex.

METHODS

We analysed data from the Wirral Child Health and Development Study (WCHADS), a prospective epidemiological study starting in pregnancy. Nine weeks after birth mothers self-reported depressive symptoms and breastfeeding status, and reported infant negative emotionality using the distress to limits subscale of the infant behaviour questionnaire (IBQ-R) when their infant was aged 9 weeks and 14 months. Maximum likelihood estimations made use of data from 857 mother-infant pairs.

RESULTS

At 9 weeks of age, maternal postnatal depressive symptoms were positively associated with infant distress to limits; however, this effect was not moderated by infant sex or breastfeeding. At age 14 months, the association between postnatal depression symptoms and distress to limits was greatest in the breastfed females, whereas the association was smaller, but still significant, in the non-breastfed females. For males, the association was non-significant in both the breastfed and non-breastfed groups. A test of sex difference between breastfed males and females was significant.

CONCLUSIONS

We provide evidence that effects of maternal postnatal depression on child emotional outcomes are moderated by breastfeeding status and differ by infant sex. Female vulnerability to elevated maternal breastmilk glucocorticoids may, at least in part, explain these effects.

Maternal stress effects on infant development in wild Verreaux's sifaka (Propithecus verreauxi)

Abstract

Maternal effects mediated by nutrients or specific endocrine states of the mother can affect infant development. Specifically, pre- and postnatal maternal stress associated with elevated glucocorticoid (GC) output is known to influence the phenotype of the offspring, including their physical and behavioral development. These developmental processes, however, remain relatively poorly studied in wild vertebrates, including primates with their relatively slow life histories. Here, we investigated the effects of maternal stress, assessed by fecal glucocorticoid output, on infant development in wild Verreaux’s sifakas (Propithecus verreauxi), a group-living Malagasy primate. In a first step, we investigated factors predicting maternal fecal glucocorticoid metabolite (fGCM) concentrations, how they impact infants’ physical and behavioral development during the first 6 months of postnatal life as well as early survival during the first 1.5 years of postnatal life. We collected fecal samples of mothers for hormone assays and behavioral data of 12 infants from two birth cohorts, for which we also assessed growth rates. Maternal fGCM concentrations were higher during the late prenatal but lower during the postnatal period compared to the early/mid prenatal period and were higher during periods of low rainfall. Infants of mothers with higher prenatal fGCM concentrations exhibited faster growth rates and were more explorative in terms of independent foraging and play. Infants of mothers with high pre- and postnatal fGCM concentrations were carried less and spent more time in nipple contact. Time mothers spent carrying infants predicted infant survival: infants that were more carried had lower survival, suggesting that they were likely in poorer condition and had to be cared for longer. Thus, the physical and behavioral development of these young primates were impacted by variation in maternal fGCM concentrations during the first 6 months of their lives, presumably as an adaptive response to living in a highly seasonal, but unpredictable environment.

Significance statement

The early development of infants can be impacted by variation in maternal condition. These maternal effects can be mediated by maternal stress (glucocorticoid hormones) and are known to have downstream consequences for behavior, physiology, survival, and reproductive success well into adulthood. However, the direction of the effects of maternal physiological GC output on offspring development is highly variable, even within the same species. We contribute comparative data on maternal stress effects on infant development in a Critically Endangered primate from Madagascar. We describe variation in maternal glucocorticoid output as a function of ecological and reproductive factors and show that patterns of infant growth, behavioral development, and early survival are predicted by maternal glucocorticoids. Our study demonstrates how mothers can influence offspring fitness in response to challenging environmental conditions.

Objective Assessment of Temperament in Temperamentally Vulnerable Children: Role in the Studies on Their Stress Levels

Under conditions of suboptimal parental care, children with specific temperamental features have been shown to be especially vulnerable to the effects of stress. Most studies of temperamentally vulnerable children have been conducted using parental questionnaires, which are unfortunately not completely objective. An alternative approach, the use of objective methods for assessing temperament in childhood, can and should be used to study the impact of poor parenting quality on children's stress levels, an important factor in child development. Although studies using such objective methods exist, they are quite rare. A PubMed search identified twelve articles reviewed here. Existing data indicate that, in general, higher basal cortisol and cortisol stress response are associated with "reactive" temperament: shyness, fearfulness, behavioral inhibition, and negative affectivity. Furthermore, child temperament interacts with the quality of parental care to predict cortisol levels in early childhood. Accordingly, in the context of inadequate parental care, temperamentally vulnerable children with "reactive" temperaments are particularly at risk for negative effects of stress. Studies of stress-by-parental-care-interactions are essential for preventing long-term mental problems and problems with physical health that could occur in temperamentally vulnerable children who receive suboptimal parental care.

Chrononutrition and Breast Milk: A Review of the Circadian Variation of Hormones Present in Human Milk

Introduction

Breast milk contains a wide range of hormones, nutrients, and bioactive compounds. Chrononutrition looks at the interaction between food, both meal timing and meal composition, and circadian rhythms.

Method

This review is a continuation on series on chrononutrition and breast milk. All human studies published in English were included regardless of location or year of publication.

Results

This review identifies the hormonal circadian variation researched in breast milk to date for melatonin, cortisol, cortisone, leptin, and insulin.

Conclusion

The circadian variation observed in some hormones reinforces the superiority of breast milk over formula milk. Melatonin has been the most studied, but more research for all the hormones is needed due to various gaps in the literature and varying levels of study quality. There is insufficient evidence to make recommendations specifically targeting the lactating mother, but we identify and recommend several ideas for future research.

Maternal effects in mammals: Broadening our understanding of offspring programming

The perinatal period is a sensitive time in mammalian development that can have long-lasting consequences on offspring phenotype via maternal effects. Maternal effects have been most intensively studied with respect to two major conditions: maternal diet and maternal stress. In this review, we shift the focus by discussing five major additional maternal cues and their influence on offspring phenotype: maternal androgen levels, photoperiod (melatonin), microbiome, immune regulation, and milk composition. We present the key findings for each of these topics in mammals, their mechanisms of action, and how they interact with each other and with the maternal influences of diet and stress. We explore their impacts in the contexts of both predictive adaptive responses and the developmental origins of disease, identify knowledge gaps and research opportunities in the field, and place a particular emphasis on the application and consideration of these effects in non-model species and natural ecological systems.

Maternal Supply of Both Arachidonic and Docosahexaenoic Acids Is Required for Optimal Neurodevelopment

During the last trimester of gestation and for the first 18 months after birth, both docosahexaenoic acid,22:6n-3 (DHA) and arachidonic acid,20:4n-6 (ARA) are preferentially deposited within the cerebral cortex at a rapid rate. Although the structural and functional roles of DHA in brain development are well investigated, similar roles of ARA are not well documented. The mode of action of these two fatty acids and their derivatives at different structural-functional roles and their levels in the gene expression and signaling pathways of the brain have been continuously emanating. In addition to DHA, the importance of ARA has been much discussed in recent years for fetal and postnatal brain development and the maternal supply of ARA and DHA. These fatty acids are also involved in various brain developmental processes; however, their mechanistic cross talks are not clearly known yet. This review describes the importance of ARA, in addition to DHA, in supporting the optimal brain development and growth and functional roles in the brain.

A bioecocultural approach to supporting adolescent mothers and their young children in conflict-affected contexts

An estimated 12 million girls aged 15-19 years, and 777,000 girls younger than 15 give birth globally each year. Contexts of war and displacement increase the likelihood of early marriage and childbearing. Given the developmentally sensitive periods of early childhood and adolescence, adolescent motherhood in conflict-affected contexts may put a family at risk intergenerationally. We propose that the specifics of normative neuroendocrine development during adolescence, including increased sensitivity to stress, pose additional risks to adolescent girls and their young children in the face of war and displacement, with potential lifelong consequences for health and development. This paper proposes a developmental, dual-generational framework for research and policies to better understand and address the needs of adolescent mothers and their small children. We draw from the literature on developmental stress physiology, adolescent parenthood in contexts of war and displacement internationally, and developmental cultural neurobiology. We also identify culturally meaningful sources of resilience and provide a review of the existing literature on interventions supporting adolescent mothers and their offspring. We aim to honor Edward Zigler's groundbreaking life and career by integrating basic developmental science with applied intervention and policy.

Maternal glucocorticoids have minimal effects on HPA axis activity and behavior of juvenile wild North American red squirrels

As a response to environmental cues, maternal glucocorticoids (GCs) may trigger adaptive developmental plasticity in the physiology and behavior of offspring. In North American red squirrels (Tamiasciurus hudsonicus), mothers exhibit increased GCs when conspecific density is elevated, and selection favors more aggressive and perhaps more active mothers under these conditions. We tested the hypothesis that elevated maternal GCs cause shifts in offspring behavior that may prepare them for high-density conditions. We experimentally elevated maternal GCs during gestation or early lactation. We measured two behavioral traits (activity and aggression) in weaned offspring using standardized behavioral assays. Because maternal GCs may influence offspring hypothalamic-pituitary-adrenal (HPA) axis dynamics, which may in turn affect behavior, we also measured the impact of our treatments on offspring HPA axis dynamics (adrenal reactivity and negative feedback), and the association between offspring HPA axis dynamics and behavior. Increased maternal GCs during lactation, but not gestation, slightly elevated activity levels in offspring. Offspring aggression and adrenal reactivity did not differ between treatment groups. Male, but not female, offspring from mothers treated with GCs during pregnancy exhibited stronger negative feedback compared with those from control mothers, but there were no differences in negative feedback between lactation treatment groups. Offspring with higher adrenal reactivity from mothers treated during pregnancy (both controls and GC-treated) exhibited lower aggression and activity. These results suggest that maternal GCs during gestation or early lactation alone may not be a sufficient cue to produce substantial changes in behavioral and physiological stress responses in offspring in natural populations.

The Relationship Between Internalized Weight Stigma During Pregnancy and Breastfeeding: A Prospective Longitudinal Study

OBJECTIVE

This study aimed to examine the relationship between internalized weight stigma during pregnancy and breastfeeding outcomes at 1 month post partum among individuals with prepregnancy overweight or obesity. Secondarily, the study explored the temporal stability of internalized weight stigma from the third trimester to 1 month post partum via the Weight Bias Internalization Scale (WBIS).

METHODS

A total of 103 pregnant individuals with overweight or obesity were recruited for this study. Participants completed the WBIS during the third trimester and self-reported breastfeeding initiation, continuation, and exclusivity outcomes at 1 month post partum. A paired t test and binomial logistic regression were conducted with covariates hierarchically added to the model.

RESULTS

The average prepregnancy BMI was 33.53 (SD 7.17) kg/m² (range = 25.4-62), and average prenatal WBIS scores were 25.95 (SD 11.83). No difference was found in mean prenatal and postpartum scores (25.95 [SD 11.83]; 26.86 [SD 13.03], respectively; t₉₄ = -0.83, P = 0.41), evidencing temporal stability in WBIS scores from pre to post partum. Prenatal WBIS scores did not predict breastfeeding initiation, continuation, or exclusivity at 1 month post partum in either unadjusted or adjusted models.

CONCLUSIONS

Collectively, this sample displayed low weight bias internalization, which was not predictive of breastfeeding initiation, continuation, or exclusivity at 1 month post partum. Future research is needed to develop a pregnancy-specific weight stigma measure.

Promoting and Protecting Human Milk and Breastfeeding in a COVID-19 World

The global COVID-19 pandemic has put enormous stress on healthcare systems and hospital staffing. However, through all this, families will continue to become pregnant, give birth, and breastfeed. Unfortunately, care of the childbearing family has been de-prioritized during the pandemic. Additionally, many healthcare practices during the pandemic have not been positive for the childbearing family or breastfeeding. Despite recommendations from the World Health Organization to promote early, direct breastfeeding and skin to skin contact, these and other recommendations are not being followed in the clinical setting. For example, some mothers have been forced to go through labor and birth alone in some institutions whilst some hospitals have limited or no parental visitation to infants in the NICU. Furthermore, hospitals are discharging mothers and their newborns early, limiting the amount of time that families receive expert lactation care, education, and technical assistance. In addition, some hospitals have furloughed staff or transferred them to COVID-19 wards, further negatively impacting direct care for families and their newborns. We are concerned that these massive changes in the care of childbearing families will be permanently adopted. Instead, we must use the pandemic to underscore the importance of human milk and breastfeeding as lifesaving medical interventions. We challenge healthcare professionals to change the current prenatal and post-birth practice paradigms to protect lactation physiology and to ensure that all families in need receive equal access to evidence-based lactation education, care and technical assistance.

Shortening sow restraint period during lactation improves production and decreases hair cortisol concentrations in sows and their piglets

Food animal welfare is an issue of great concern, as society has a responsibility for animals under human care. Pork is the most consumed meat worldwide, with more than a billion pigs being slaughtered globally every year. Still, in most countries, sows are restrained in farrowing crates throughout lactation. In these crates, sows are confined with bars to an area that is just slightly larger than their body. Thus, moving and turning around, grooming, or expressing other natural behaviors are typically impossible. In this study, we utilized a simple and practical modification of conventional farrowing crates to designed farrowing pens, by removable confinement bars, which provide the flexibility to change the housing system from one to another. Our objective was to examine the parameters of production and hair cortisol concentrations after different restraint periods during lactation. Analyses included data from 77 sows and their 997 piglets. Sows were housed in farrowing crates, but the confinement bars were removed after different periods, from 3 days post-farrowing to full restraint. For certain analyses, sows were grouped into Short or Long Restraint groups (3-10 days vs 13-24 days, respectively). Multiple linear regression revealed that for any additional day in restraint of the sows, piglets' weaning rate decreases by 0.4% (P < 0.05). Moreover, the total number of weaned piglets per litter was higher in the Short Restraint group as compared to the Long Restraint group (10.4 ± 0.3 vs 9.7 ± 0.3, respectively; P < 0.05). Accordingly, total litter weight on the weaning day tended to be higher in the Short Restraint group (68.8 ± 2.2 vs 64.9 ± 1.8 kg; P = 0.1210). The requirement for medical treatments during lactation (e.g., antibiotics, NSAID) tended to be less frequent in the Short Restraint group (Sows: 21.9% vs 40%; P = 0.1219. Piglets: 2.4% vs 17.1%; P = 0.0609). Hair cortisol as a marker for chronic stress during lactation decreased when the restraint period was shortened in both sows and piglets. Our analysis revealed that sows' hair cortisol is a significant mediator between the restraint of the sow and its piglets' hair cortisol (Sobel test; P < 0.05). For every day of sows' restraint, sows' hair cortisol increased by 0.5 pg/mg, and for any additional unit of sows' hair cortisol, piglets' hair cortisol increased by 0.36 pg/mg. In conclusion, sustainable swine farming management can be beneficial for both animals and farmers; limiting sow restraint during lactation is expected to reduce stress, enhance welfare and production, and potentially improve the economics of swine operations.

Associations between maternal socioeconomic, psychosocial and seasonal factors, infant characteristics and human milk cortisol concentrations

OBJECTIVES

Glucocorticoids are one component of human milk (HM) potentially affecting offspring development. Previous studies have identified various maternal, obstetric and socioeconomic characteristics that are associated with HM cortisol concentration but the literature is still scarce concerning these determinants in human populations. We aimed to identify which factors are linked with HM cortisol concentration at 2 months postpartum.

METHODS

We analyzed data from 340 lactating Finnish mothers using ordinary least squares regression with log-transformed HM cortisol concentration as the dependent variable. Potential predictors included obstetric and maternal factors (maternal age, parity status, delivery mode, gestational age, pre-pregnancy obesity, and smoking in pregnancy), socioeconomic status (education and socioeconomic class), subjective economic well-being, maternal psychosocial factors (postpartum depression and anxiety symptoms), infant sex and age, and HM sample characteristics (time of the day and season of the year at sample collection).

RESULTS

The strongest and most robust predictors were season of the year of sample collection and parity status. HM cortisol concentration was significantly higher for primiparas than multiparas. HM samples collected in summer showed significantly higher cortisol concentrations than those collected in winter, spring or autumn.

CONCLUSIONS

The findings suggest that parity and season of the year at sample collection may be important factors to control for when examining HM cortisol. The strongest and most robust associations were related to maternal and sample characteristics and not to socioeconomic and psychosocial distress. This may be related to the fact that the study was conducted in a low-risk population.

Assessing the Multivariate Relationship between the Human Infant Intestinal Exfoliated Cell Transcriptome (Exfoliome) and Microbiome in Response to Diet

Gut microbiota and the host exist in a mutualistic relationship, with the functional composition of the microbiota strongly influencing the health and well-being of the host. In addition to the standard differential expression analysis of host genes to assess the complex cross-talk between environment (diet), microbiome, and host intestinal physiology, data-driven integrative approaches are needed to identify potential biomarkers of both host genes and microbial communities that characterize these interactions. Our findings demonstrate that the complementary application of univariate differential gene expression analysis and multivariate approaches such as sparse Canonical Correlation Analysis (sCCA) and sparse Principal Components Analysis (sPCA) can be used to integrate data from both the healthy infant gut microbial community and host transcriptome (exfoliome) using stool derived exfoliated cells shed from the gut. These approaches reveal host genes and microbial functional categories related to the feeding phenotype of the infants. Our findings also confirm that combinatorial noninvasive -omic approaches provide an integrative genomics-based perspective of neonatal host-gut microbiome interactions.

Human Milk Glucocorticoid Levels Are Associated With Infant Adiposity and Head Circumference Over the First Year of Life

Human milk (HM) is a complex and dynamic biological fluid, which contains appreciable concentrations of the glucocorticoids, cortisol and cortisone. Experimental studies in non-human primates suggest the HM glucocorticoids' impact on infant growth and body composition. In this current study, analysis is made of the relationships between HM glucocorticoid concentrations and the infant growth and development over the first year of life. HM was collected by lactating healthy women (n = 18), using a standardized protocol, at 2, 5, 9, and 12 months after childbirth. Cortisol and cortisone concentrations in the HM were measured using liquid chromatography mass spectrometry. Infant weight, length and head circumference were measured by standard protocols and percentage fat mass (% FM) determined by whole body bioimpedance. Cortisol and cortisone concentrations were unaltered over the analyzed lactation period (2–12 months), and were altered by infant sex. Although, HM cortisol was positively associated with infant percentage fat mass (% FM) (p = 0.008) and cortisone positively associated with infant head circumference (p = 0.01). For the first 12 months of life, the concentration of HM glucocorticoids levels was positively associated with infant adiposity (%FM) and head circumference. This preliminary evidence provides insight to a possible relationship between ingested HM glucocorticoids and infant body composition. Further studies are required to determine the mechanisms regulating HM glucocorticoids.

Interactions between cortisol and lipids in human milk

Background

Human breast milk is one of the key early postnatal biological exposures for the developing child. It includes bioactive compounds, such as cortisol and fatty acids, which may be linked via the mother’s lipid metabolism.

Methods

This study investigated the associations between cortisol and lipids in human milk at the infant age of 2.5 months. Human milk cortisol concentrations were measured using luminescence immunoassay, and two groups of milks (n = 50 each) were formed based on either high (> 10 nmol/L) or low (< 3 nmol/L) cortisol levels. Lipids, as fatty acid content and composition of neutral (triacylglycerol-rich) and polar (phospholipid-rich) lipids, were measured with gas chromatography. The samples originated from the FinnBrain Birth Cohort Study.

Results

The percentage of phospholipid-rich lipids of total lipids was 33.08% ± 1.33%. In triacylglycerol-rich lipids, high cortisol level in milk was associated with higher lauric (12:0, mass % and mg/mL), myristic (14:0, mass % and mg/mL), eicosenoic (20:1n − 9, mass %), docosenoic (22:1n − 9, mass %, and mg/mL) acids, and to lower palmitic acid (16:0, mass %) compared with low cortisol levels in milk. In phospholipid-rich lipids, high cortisol level was associated with higher myristic (14:0, mass %) and docosenoic (22:1n − 9, mass %) acids. After adjusting for pre-pregnancy BMI and sampling time by linear regression, the milk cortisol remained a significant predictor for lauric and myristic acids in triacylglycerol-rich lipids, and myristic and docosenoic acid in phospholipid-rich lipids (β = 0.23 to 0.38 and p < 0.05 for each).

Conclusions

This study revealed certain significant associations between milk cortisol and the fatty acid composition of human milk, indicating that cortisol might be one of the factors affecting the origin of the lipids in human milk.

Diurnal rhythmicity in breast-milk glucocorticoids, and infant behavior and sleep at age 3 months

PURPOSE

In previous studies, associations between breast-milk cortisol levels obtained on one occasion and infant neurodevelopment were demonstrated. However, more recent evidence indicates that breast-milk cortisol and cortisone concentrations follow the diurnal rhythm of maternal hypothalamus-pituitary-adrenal axis, peaking in the early morning and with a nadir at midnight. We studied associations between breast-milk glucocorticoid (GC) rhythmicity, and infant behavior and sleep.

METHODS

We included 59 mothers, and their infants, of whom 17 had consulted an expert center during pregnancy for an increased risk of psychological distress. At 1 month postpartum, breast milk was sampled (on average six times) over a 24 h period for assessment of cortisol and cortisone using LC-MS/MS, and experienced maternal distress was assessed using the Hospital Anxiety and Depression Scale questionnaire. Three months after birth, infant behavior was assessed with the Infant Behavior Questionnaire, and infant sleep pattern was quantified by questionnaire. Associations between breast-milk GC rhythm parameters (maximum, delta, and Area Under the Curve increase and ground) and infant behavior and sleep were tested with linear regression analyses.

RESULTS

No consistent associations between breast-milk GC rhythm parameters and infant behavior or sleep were found.

CONCLUSIONS

Breast-milk GC rhythmicity at 1 month postpartum was not associated with infant behavior or sleep at the age of 3 months. Findings from previous studies linking breast-milk cortisol to infant neurodevelopment might be biased by the lack of GC measurements across the full diurnal cycle, and should therefore be interpreted with caution.

Human milk cortisol and immune factors over the first three postnatal months: Relations to maternal psychosocial distress

Background

Many biologically active factors are present in human milk including proteins, lipids, immune factors, and hormones. The milk composition varies over time and shows large inter-individual variability. This study examined variations of human milk immune factors and cortisol concentrations in the first three months post-partum, and their potential associations with maternal psychosocial distress.

Methods

Seventy-seven healthy mothers with full term pregnancies were enrolled, of which 51 mothers collected morning milk samples at 2, 6 and 12 weeks post-delivery. Maternal psychosocial distress was assessed at 6 weeks post-delivery using questionnaires for stress, anxiety, and depressive symptoms. Immune factors were determined using multiplex immunoassays and included innate immunity factors (IL1β, IL6, IL12, IFNγ, TNFα), acquired immunity factors (IL2, IL4, IL10, IL13, IL17), chemokines (IL8, Groα, MCP1, MIP1β), growth factors (IL5, IL7, GCSF, GMCSF, TGFβ2) and immunoglobulins (IgA, total IgG, IgM). Cortisol was quantified using liquid chromatography-tandem mass spectrometry. A linear mixed effects model was fit to test whether stress, anxiety, and depressive symptoms individually predicted human milk cortisol concentrations after accounting for covariates. Repeated measurement analyses were used to compare women with high (n = 13) versus low psychosocial distress (n = 13) for immune factors and cortisol concentrations.

Results

Virtually all immune factors and cortisol, with the exception of the granulocyte-macrophage colony-stimulating factor (GMCSF), were detected in the human milk samples. The concentrations of the immune factors decreased during the first 3 months, while cortisol concentrations increased over time. No correlation was observed between any of the immune factors and cortisol. No consistent relationship between postnatal psychosocial distress and concentrations of immune factors was found, whereas higher psychosocial distress was predictive of higher cortisol concentrations in human milk.

Conclusion

In the current study we found no evidence for an association between natural variations in maternal distress and immune factor concentrations in milk. It is uncertain if this lack of association would also be observed in studies with larger populations, with less uniform demographic characteristics, or with women with higher (clinical) levels of anxiety, stress and/or depressive symptoms. In contrast, maternal psychosocial distress was positively related to higher milk cortisol concentrations at week 2 post-delivery. Further investigation on maternal psychosocial distress in relation to human milk composition is warranted.

Mothering revisited: A role for cortisol?

This selective review first describes the involvement of the maternal hypothalamic-pituitary-adrenal (HPA) axis during pregnancy and the postpartum period, and the relation between peripartum HPA axis function and maternal behavior, stress reactivity and emotional dysregulation in human mothers. To provide experimental background to this correlational work, where helpful, animal studies are also described. It then explores the association between HPA axis function in mothers and their infants, under ongoing non-stressful conditions and during stressful challenges, the moderating role of mothers' sensitivity and behavior in the mother-child co-regulation and the effects of more traumatic risk factors on these relations. The overarching theme being explored is that the HPA axis - albeit a system designed to function during periods of high stress and challenge - also functions to promote adaptation to more normative processes, shown in the new mother who experiences both high cortisol and enhanced attraction and attention to and recognition of, their infants and their cues. Hence the same HPA system shows positive relations with behavior at some time points and inverse ones at others. However, the literature is not uniform and results vary widely depending on the number, timing, place, and type of samplings and assessments, and, of course, the population being studied and, in the present context, the state, the stage, and the stress levels of mother and infant.

Nutritional and immunological factors in breast milk: A role in the intergenerational transmission from maternal psychopathology to child development

Perinatal psychopathologies affect more than 25% of women during and after their gestational period. These psychiatric disorders can potentially determine important biological variations in their organisms, affecting many different physiological and metabolic pathways. Of relevance, any of these changes occurring in the mother can alter the normal composition of breast milk, particularly the concentration of nutritional and inflammatory components, which play a role in child brain functioning and development. Indeed, there is evidence showing that changes in milk composition can contribute to cognitive impairments and alterations in mental abilities in children. This review aims to shed light on the unique intergenerational role played by breast milk composition, from maternal psychopathologies to child development.

'Optimising' breastfeeding: what can we learn from evolutionary, comparative and anthropological aspects of lactation?

BACKGROUND

Promoting breastfeeding is an important public health intervention, with benefits for infants and mothers. Even modest increases in prevalence and duration may yield considerable economic savings. However, despite many initiatives, compliance with recommendations is poor in most settings - particularly for exclusive breastfeeding. Mothers commonly consult health professionals for infant feeding and behavioural problems.

MAIN BODY

We argue that broader consideration of lactation, incorporating evolutionary, comparative and anthropological aspects, could provide new insights into breastfeeding practices and problems, enhance research and ultimately help to develop novel approaches to improve initiation and maintenance. Our current focus on breastfeeding as a strategy to improve health outcomes must engage with the evolution of lactation as a flexible trait under selective pressure to maximise reproductive fitness. Poor understanding of the dynamic nature of breastfeeding may partly explain why some women are unwilling or unable to follow recommendations.

CONCLUSIONS

We identify three key implications for health professionals, researchers and policymakers. Firstly, breastfeeding is an adaptive process during which, as in other mammals, variability allows adaptation to ecological circumstances and reflects mothers' phenotypic variability. Since these factors vary within and between humans, the likelihood that a 'one size fits all' approach will be appropriate for all mother-infant dyads is counterintuitive; flexibility is expected. From an anthropological perspective, lactation is a period of tension between mother and offspring due to genetic 'conflicts of interest'. This may underlie common breastfeeding 'problems' including perceived milk insufficiency and problematic infant crying. Understanding this - and adopting a more flexible, individualised approach - may allow a more creative approach to solving these problems. Incorporating evolutionary concepts may enhance research investigating mother-infant signalling during breastfeeding; where possible, studies should be experimental to allow identification of causal effects and mechanisms. Finally, the importance of learned behaviour, social and cultural aspects of primate (especially human) lactation may partly explain why, in cultures where breastfeeding has lost cultural primacy, promotion starting in pregnancy may be ineffective. In such settings, educating children and young adults may be important to raise awareness and provide learning opportunities that may be essential in our species, as in other primates.

Human Milk Omega-3 Fatty Acid Composition is Associated with Infant Temperament

There is growing evidence that omega-3 (n-3) polyunsaturated fatty-acids (PUFAs) are important for the brain development in childhood and are necessary for an optimal health in adults. However, there have been no studies examining how the n-3 PUFA composition of human milk influences infant behavior or temperament. To fill this knowledge gap, 52 breastfeeding mothers provided milk samples at 3 months postpartum and completed the Infant Behavior Questionnaire (IBQ-R), a widely used parent-report measure of infant temperament. Milk was assessed for n-3 PUFAs and omega-6 (n-6) PUFAs using gas-liquid chromatography. The total fat and the ratio of n-6/n-3 fatty acids in milk were also examined. Linear regression models revealed that infants whose mothers' milk was richer in n-3 PUFAs had lower scores on the negative affectivity domain of the IBQ-R, a component of temperament associated with a risk for internalizing disorders later in life. These associations remained statistically significant after considering covariates, including maternal age, marital status, and infant birth weight. The n-6 PUFAs, n-6/n-3 ratio, and total fat of milk were not associated with infant temperament. These results suggest that mothers may have the ability to shape the behavior of their offspring by adjusting the n-3 PUFA composition of their milk.

Maternal and Neonatal Hair Cortisol Levels and Psychological Stress Are Associated With Onset of Secretory Activation of Human Milk Production

BACKGROUND

Several factors can influence the production of mothers' own milk.

PURPOSE

To assess the influence of maternal psychological stress, maternal cortisol levels, and neonatal hair cortisol levels on timing of secretory activation.

METHODS

A prospective study was conducted at 2 public health centers in Andalusia, Spain. Participants were 60 pregnant women and their 60 neonates. Hair cortisol levels and psychological stress (pregnancy-specific stress [Prenatal Distress Questionnaire, PDQ] and perceived stress [Perceived Stress Scale, PSS]) were evaluated during the third trimester and the postpartum period. This study was part of the GESTASTRESS cohort study on the effects of stress during pregnancy.

RESULTS

Higher PDQ and PSS scores (P < .05) in the third trimester were associated with later onset of secretory activation. Higher postpartum maternal hair cortisol levels were associated with a delayed secretory activation of mother's own milk (P < .05).

IMPLICATIONS FOR RESEARCH

Future studies should look at the influence of psychological stress and cortisol levels on hormones involved in mother's own milk production.

IMPLICATIONS FOR PRACTICE

Neonatal nurses and other healthcare providers should be familiar with levels of neonates' exposure to maternal prenatal stress prior to birth.

Trajectories of maternal pre- and postnatal anxiety and depressive symptoms and infant fear: Moderation by infant sex

BACKGROUND

Prior work has examined the links between pre- and postnatal maternal distress and infant negative affectivity; however, there is little understanding about how the continuity of infant exposure to pre- and postnatal maternal distress relates to infant development. This study investigated the continuity of maternal pre- and postnatal depressive and anxiety symptoms and their relations with infant fear among 391 mother-infant dyads. An additional aim was to consider infant sex as a moderating factor.

METHODS

Maternal anxiety and depressive symptoms were measured during gestational weeks 14, 24 and 34 and 3 and 6 months postpartum. Subsequently, infant fear was measured using mother reports (IBQ-R) at 6 months and in a laboratory setting (Lab-TAB Masks episode) at 8 months. Using growth mixture modeling, a three-class model describing the course of maternal symptoms across pregnancy and the early postnatal period was identified, consisting of mothers with "Consistently Low Distress", "Prenatal-Only Distress", and "Consistently High Distress".

RESULTS

Infant girls exposed to prenatal-only maternal distress were higher in observed fear than infant boys exposed to prenatal-only distress. Infant girls exposed to consistently high distress also showed lower observed fear than their counterparts exposed to prenatal-only maternal distress.

LIMITATIONS

The main limitation of the study is the relatively small group size within the Consistently High subgroup.

CONCLUSIONS

The findings suggest that girls might be particularly sensitive to maternal distress, and that prenatal-only and continuous distress exposure are differentially related to female infant fear.