Welcome to the N&G 2023 Meeting Calendar
The conference will officially run on BDT - British Daylight Time (UTC+1)
To convert the congress times to your local time Click Here
Mother-Infant Conflict and "Signalling" via Breast Milk
Abstract
Abstract Body
Lactation is a dynamic process in which the mother and the infant actively compete over how much of the mother's resources will be invested in breast milk during lactation. The infant's demand for milk can be expressed through behaviour, appetite, vocalisation, and/or non-nutritive suckling, while the mother's response can be shown in nursing behaviour, milk production, and/or milk composition. It is hypothesised that these relationships may shape infant behaviour and feeding, particularly appetite regulation, and may thus influence infant growth and development. However, there are many unanswered questions about this tug-of-war, including who is more in charge, how the mother allocates her energy economically to maximise her offspring's fitness, and whether, for instance, an abundance of maternal energy will result in a lessening of tension. It is also acknowledged that maternal emotion could influence breast milk synthesis and ejection, highlighting the need for minimising maternal stress or promoting relaxation during the postpartum period. Furthermore, the mother's energy reserves might be considerably depleted during the early postnatal period as she recovers from birth while continuing to invest in her infant, primarily through breast milk. Because breastfeeding requires high energy, postpartum distress may intensify the tug-of-war by affecting the mother's energy budget. Aiming to reduce this mother-infant conflict, we conducted a randomised controlled trial by manipulating the maternal psychological state using relaxation therapy (breastfeeding meditation) to see the effect on maternal stress, breast milk production, and infant behaviour and growth. The trial was conducted in Malaysia among first-time mothers and their full-term infants (n = 64), who were followed up on from birth to 16 weeks in three home visit sessions. Maternal stress and infant behaviour were assessed, infant growth was monitored, and breast milk samples were collected at all visit sessions. This trial found significant relaxation therapy intervention benefits for both mothers and infants, with the strongest evidence on maternal stress reduction and achieving optimal infant weight and BMI. The intervention therapy also showed a significant effect on infant behaviour, with longer infant sleeping duration, and on milk composition, with a greater decrease in milk cortisol concentrations at the early home visit. The pooled results from early to later home visits also revealed that the intervention might have long-term or cumulative consequences on elevating total energy levels in breast milk. Overall, listening to the relaxation treatment lowered maternal stress and modified the breast milk composition, which had an influence on infant sleeping behaviour and growth. The benefits of relaxation treatment on infant outcomes might be mediated by physiological signalling via changes in breast milk composition, or behavioural signalling via the influence on sleeping duration. In conclusion, encouraging relaxation during breastfeeding shifted the mother-infant tug-of-war toward a positive energy balance (reduced mother-infant conflict), leading to a greater energy investment in milk production and promoting healthy newborn growth. Nevertheless, it is important to consider the study's main limitations, which include the small sample size and non-blinded intervention due to the nature of behavioural intervention.
Maternal Inflammation and Milk Composition
Abstract
Abstract Body
Systemic inflammation plays an important role in the etiology of most chronic diseases but its role in shaping breast milk composition and the developing infant gut microbiome have only recently been investigated. The MILk Study is an observational cohort of 500 healthy mother-infant dyads followed from pregnancy to 6 months postpartum. Its primary goal is to assess the role of maternal obesity, diabetes, diet, and genetic factors in shaping variation in human milk, and whether differences in milk alter infant growth and health. Recent multi-omic analyses in a subset of 242 of the dyads utilized genomic material from mammary epithelial cells and other cell types found in human milk to provide insight into individual variation in mammary gene expression signatures. Our data show that 1) milk interleukin-6 (IL-6) concentration, a biomarker of inflammation, explained the most variation in milk gene expression, being correlated with expression levels of over 2000 genes, most of which fell into “inflammatory response” and related pro-inflammatory gene pathways; 2) that women with gestational diabetes had higher milk concentrations of both CRP and sialylated human milk oligosaccharides (HMOs), the latter of which were correlated with gene expression levels in multiple inflammatory pathways, and 3) that expression of JAK/STAT pathway genes in milk, particularly STAT1, was inversely correlated with the abundance and growth of infant fecal Bifidobacterium infantis abundance, a dominant microbe in the gut of breastfed infants that is known to beneficially shape the biochemical and immunological environment of the intestinal epithelium. Thus, our results suggest that mammary inflammation, as indexed by elevated IL-6 levels in the milk and evidenced by activation of pro-inflammatory gene pathways, may be an important driver of variation in milk composition, with potential effects on the infant gut microbiome.
Maternal Capital, Stress and Infant Growth
Abstract
Abstract Body
Maternal capital is a broad term referring to any aspect of maternal phenotype, including somatic, cognitive, psychological and social traits, that represent the resources that are available for maternal investment in the offspring. During pregnancy, maternal capital is the only direct source of signals that a fetus is exposed to, while during lactation the infant is exposed directly to other environmental signals, but maternal capital remains the main environment that the infant is exposed to and responds to. Previous research has shown that maternal capital was associated with infant growth, nutritional status, adult size, and even educational attainment. Therefore, strategies that enhance maternal capital could potentially improve children’s health and development by improving maternal investment in the offspring during critical windows of growth. One such strategy is reducing maternal stress. We previously showed in a randomized controlled trial that reducing maternal stress by asking breastfeeding mothers of late preterm and early term infants to listen to a relaxation therapy, resulted in higher infant weight gain. The intervention also promoted maternal capital by improving verbal memory scores of mothers in the intervention group. Additionally, there were significant interactions between the intervention group assignment and maternal capital which indicated that the intervention had greater effects on infant weight, length, crying, and maternal responsiveness to infant cues among mothers with lower maternal capital. The findings suggested that a relaxation intervention could buffer against maternal capital insults, as the effects of low maternal capital appeared most detrimental to infants whose mothers did not receive the intervention. Overall, understanding and applying evolutionary concepts such as maternal capital to health-related studies could improve understanding of how the environment interacts with the mother, milk and infant. It could also help to better predict the outcome of interventional studies and achieve the desired results such as improved infant growth and promotion of breastfeeding.