Maternal stress is associated with higher protein-bound amino acid concentrations in human milk

Maternal sleep and psychological status in the postpartum period are associated with functional protein alterations in breast milk:a mother-infant cohort study

BACKGROUND & AIMS

Postpartum sleep disorder and mental disorders are common unpleasant conditions faced by women after delivery, and they have many adverse effects on both mothers and infants. It is unclear whether breast milk composition is affected by maternal sleep, psychological state, diet and gut microbiome. This study aims to explore the effects of these key factors on the functional protein components of breast milk.

METHODS

With a prospective design, this pilot study included a total of 41 postpartum women. Breast milk and maternal faecal samples collected at 42 days and 3 months postpartum were tested by liquid chromatography-mass spectrometry and 16S RNA sequencing, respectively. Sleep state, psychological state and dietary intake data were also collected from the mothers with validated questionnaires.

RESULTS

In the early postpartum period, sleep disorders and depression were associated with a decrease in the functional proteins in breast milk. Disordered sleep was significantly negatively correlated with α-lactalbumin (cor = -0.578, p < 0.001), osteopontin (cor = -0.522, p < 0.01) and κ-casein (cor = -0.451, p < 0.01). Depression was negatively correlated with αs1-casein (cor = -0.422, p < 0.01), β-casein (cor = -0.317, p < 0.05) and casein (cor = -0.318, p < 0.05). In 3 months postpartum, most associations were disappeared. But a positive correlation was observed between β-casein (cor = 0.414, p < 0.01), casein (cor = 0.372, p < 0.05), total protein (cor = 0.376, p < 0.05) and depression, while a positive correlation was found between total protein (cor = 0.357, p < 0.05) and disordered sleep at 3 months postpartum. Faecal microbiome data illustrated that changes in the gut microbiome at early postpartum were associated with sleep disorders/depression, but not with the diet. Furthermore, functional pathway analysis revealed metabolic regulation in the amino acid synthesis and metabolic pathways associated with specific microbes was involved in the reduction of breast milk protein.

CONCLUSION

Sleep disorders/depression could lead to significant changes in breast milk profiles at 42 days postpartum. Maternal gut microbiome might affect breast milk protein composition through regulating amino acid synthesis and metabolic pathways.

From Mind to Milk: The Influence of Psychological Factors on the Composition of Human Breast Milk

Background/Objectives: Breast milk is a complex fluid crucial for infant development, nutrition, and immunological and neurodevelopmental support. Recent findings suggest that factors regarding mental health, such as stress, anxiety, and postpartum depression (PPD), may influence the composition of breast milk. This review aims to synthesize current knowledge regarding the relationship between a mother's mental state and the biochemical profile of human milk, focusing mainly on nutrients, hormones, immune factors, and microbiota. Methods: A systematic literature search was conducted in PubMed and the Web of Science using predefined keywords related to psychological factors and milk composition. Studies involving validated psychological assessment tools and only human subjects were included, in accordance with PRISMA guidelines. Results: Findings indicated that maternal stress and PPD are associated with alterations in breast milk composition. Elevated cortisol and changes in melatonin and prolactin levels have been observed. Immune components, such as secretory immunoglobulin A and transforming growth factor beta 2, exhibit variable responses depending on stress type and duration. Lower concentrations of docosahexaenoic acid and polyunsaturated fatty acid have been observed among mothers diagnosed with depression. Additionally, maternal psychological distress may influence infants' gut microbiota composition, potentially affecting long-term health outcomes. Conclusions: The maternal psychological state plays an essential role in shaping the composition of human breast milk. Understanding these associations highlights the need for mental health support during the postpartum period to optimize infant development. Future research should focus on the molecular mechanisms underlying these changes and potential interventions to mitigate adverse effects.

Maternal stress in the early postpartum period is associated with alterations in human milk microbiome composition

BACKGROUND

Maternal stress is associated with negative early-life development and (mental)health outcomes. There is recent evidence that maternal stress in the postpartum period impacts the nutrient composition of human milk (HM). However, it is currently not known whether maternal stress is associated with changes in the HM microbiome during the critical early postpartum period.

METHODS

In this prospective observational cohort study, lactating women were recruited into a high-stress (HS, n = 23) and control (CTL, n = 69) group. The HS group included mothers with infants hospitalized for at least two days. Maternal stress was assessed using validated questionnaires and cortisol concentrations in hair, saliva and HM. HM was collected at days 10 and 24 and its microbiome was analyzed using 16 s rRNA sequencing. HM bacterial composition was compared between study groups and their correlation with maternal stress levels, maternal characteristics and infant outcomes was determined.

RESULTS

HM microbiome β-diversity differed significantly between study groups, with HS mothers displaying decreased abundance of Streptococcus, Gemella, and Veillonella, and increased levels of Staphylococcus, Corynebacterium and Acinetobacter compared to the control group. While the strongest correlation of β-diversity was with stress, HM microbiome β-diversity also correlated significantly with maternal education level and infant sex. No correlation between HM microbiome composition and HM cortisol concentrations was found.

CONCLUSIONS

This study demonstrates stress-associated alterations in the early HM microbiome that could potentially contribute to early gut colonization and subsequent (mental)health outcomes. Future research is needed to elucidate the physiological significance of these changes for infant development and health.

Maternal dietary protein and amino acid intake is not associated with the amino acid composition of human milk in an affluent environment

Amino acids (AA) are essential nutrients in human milk (HM) and critical for infant growth and development. Several maternal lifestyle factors have been suggested to influence HM AA composition, with possible consequences for the breastfed infant. Whether maternal dietary protein and AA intake is associated with AA concentrations in HM is still largely unknown. Therefore, the aim of this study was to investigate the association between maternal dietary AA intake and AA concentrations in HM over the first month postpartum. Data from the observational longitudinal Amsterdam Mother's Milk study were used, consisting of 123 lactating women in their first postpartum month. HM samples were collected three times, on day 10, 17 and 24 postpartum. Maternal dietary protein and AA intake on these collection days was assessed using three 24-h recalls. HM protein-bound and free AA (BAA and FAA, respectively) were analysed by liquid chromatography. Associations between maternal AA intake and AA concentrations in HM were assessed using linear mixed models. Maternal intake was negatively associated with milk concentrations of free arginine (-0·0003; P = 0·01) and free lysine (-0·0004; P = 0·03) and was positively associated with free glutamine (0·002; P = 0·03) and free threonine (0·0008; P = 0·03). However, these associations were attenuated after correction for multiple testing. Both the quality and quantity of dietary protein intake in lactating women do not seem to influence the amino composition of their breast milk when living in an affluent environment.

Acute and chronic sleep restriction differentially modify maternal behavior and milk macronutrient composition in the postpartum rat

BACKGROUNDS

Sleep restriction is considered a stressful condition itself, causing a wide variety of physiological alterations, from cognitive and hormonal to immunological status. In addition, it is established that stress in mother rats can modify milk ejection, milk composition, and maternal care of the pups. Also, sleep disturbances during the early stages of motherhood are a common feature of all studied species. In this context, while the impacts of sleep disruption in non-lactating animals were extensively investigated, its repercussions during the initial phases of motherhood have been poorly explored. Therefore, we wonder if maternal behavior, milk ejection and its macronutrient composition would be disrupted when mother rats are subjected to an additional acute or chronic sleep restriction to the already existing sleep disturbances.

METHODS

Lactating rats were implanted with unilateral electrodes for polysomnographic recordings and for deep brain electrical stimulation into mesopontine waking-promoting area (for sleep deprivation). During the early postpartum period (postpartum day 5-9), mother rats were randomly assigned into one of three groups: chronic sleep restriction group (CSR; 6 h of sleep deprivation/day for five consecutive days), acute sleep restriction group (ASR; 6 h of sleep deprivation only for one day), or undisturbed group (control group). Active maternal behaviors (retrievals of the pups into the nest, mouthing, lickings [corporal and anogenital] and sniffing the pups) and passive maternal behaviors (kyphotic and supine nursing postures) were evaluated during a 30 min period without sleep restriction immediately after the sleep restriction or control period. The litter weight gain was assessed every day, and on the last experimental session mothers were milked for posterior macronutrients analysis (protein, carbohydrates and fat).

RESULTS

When compared to control group, CSR decreased the amount of milk ejected in the middle days of the sleep restriction period, while ASR did not affect this parameter. Moreover, ASR reduced milk protein content compared to control and CSR groups. Finally, compared to the control group, CSR reduced active maternal behaviors towards the end of the treatment days.

CONCLUSIONS

We demonstrated that not only acute but also chronic sleep restriction impacts on the postpartum period, each one affecting different aspects of maternal behavior and lactation. Our results suggest the existence of a homeostatic recovery mechanism in breastfeeding during CSR, possibly ensuring the survival of the litter, while the decline in active maternal behaviors appears to be cumulative.