Human milk is a dynamic, bioactive fluid that supports infant growth, development, and immune protection. Gestational diabetes mellitus (GDM), characterised by glucose intolerance with onset during pregnancy, is associated with altered maternal metabolism that may persist postpartum and affect lactation and milk composition. To systematically evaluate and meta-analyse evidence on associations between maternal GDM and human milk composition across lactation, five electronic databases were searched for studies comparing human milk composition between mothers with and without GDM. Data were extracted for milk macronutrients, lipids, oligosaccharides, hormones and metabolic regulatory factors, immune and inflammatory factors, micronutrients and antioxidants, and multiomics across colostrum, transitional, and mature milk. Meta-analyses were conducted where possible. Fifty-two studies with 3233 mothers were included. Macronutrient content, total fat, and fatty acids were found to be similar between GDM and non-GDM milk. However, lactose concentrations were lower in GDM colostrum. In addition, mothers with GDM who were not taking docosahexaenoic acid (DHA) supplements had lower DHA concentrations than mothers without GDM. Appetite- and metabolism-related peptides were lower in colostrum, whereas other regulatory peptides were higher. Mothers with GDM had lower colostrum concentrations of human milk oligosaccharides (HMOs), including 2′-fucosyllactose and 6′-sialyllactose, with partial normalisation in mature milk. Immune, metabolomic, and proteomic findings were heterogeneous but indicated stage-dependent remodelling. GDM is associated with selective, lactation-stage-specific alterations in the bioactive and functional components of human milk rather than the disruption of core nutritional composition. The stage-specific nature of these alterations suggests that human milk composition may adapt to maternal physiological changes during lactation.

Organoids have emerged as powerful in vitro models that bridge the gap between traditional two-dimensional cultures and in vivo studies. Over the past decade, advances in stem cell biology and extracellular matrix (ECM) engineering have enabled the establishment of organoids that partially recapitulate the structural and functional features of the mammary gland. These models have provided new opportunities to investigate mammary development, lactation biology, and breast cancer. In this review, we summarize recent progress in the establishment of mammary organoids across species, including humans, mice, and livestock. We discuss the effects of cell source, ECM, and growth factors on organoid culture. We further highlight the applications of organoid culture in mammary gland development, lactation biology, drug screening, precision medicine, and cell-based milk production. Despite the large advances achieved in the technique, the current mammary organoid culture still has many limitations due to the incomplete understanding of tissue complexity, insufficient vascularization, loss of microenvironmental interactions, and challenges in reproducibility. Emerging strategies, such as multi-organ systems, three-dimensional bioprinting, and organoids-on-a-chip, offer promising approaches to improve the physiological relevance of this technique and functional maturity. Overall, mammary organoids represent a rapidly evolving platform with broad applications. They are expected to become important platforms linking mammary biology to livestock production and next-generation dairy biomanufacturing.

In Japan, a version of the Japanese Food Guide, specifically developed for pregnancy and lactation (JFGST-P/L), promotes healthy dietary habits. In the mid- to-late stages of pregnancy, it is especially important to consume the recommended additional calories and nutrients. Adherence to these guidelines also plays a key role in achieving appropriate gestational weight gain (GWG). This study investigated the relationship between adherence to these guidelines and GWG among women in the mid- to late stages of pregnancy. Data were obtained from the Maternal and Child Cohort Study, conducted at the National Center for Child Health and Development (Setagaya-ku, Tokyo, Japan). The degree of adherence to the JFGST-P/L was evaluated using scores calculated from responses to a semi-quantitative food frequency questionnaire. The participants were classified into quartiles (Q1–Q4) based on their adherence scores. GWG was classified as inadequate, adequate, or excessive according to the Ministry of Health, Labour and Welfare guidelines. The degree of JFGST-P/L adherence was divided into quartiles, and a multinomial logistic regression analysis was performed. Furthermore, the Q1 group was compared with the Q2–Q4 groups to examine the association with the risk of insufficient GWG. In the quartile analysis, no clear dose–response relationship was observed between JFGST-P/L adherence and GWG. Conversely, among Q1, an increased risk of insufficient GWG was noted compared to the Q2–Q4 group (Unadjusted OR 1.389, 95%CI 1.008–1.913). In this study, the lowest degree of adherence to the JFGST-P/L among pregnant women was associated with inadequate GWG.

Exclusive breastfeeding in the first 6 months of life is crucial for the health of mothers and babies in low-and middle-income countries. Milk mid-chain fatty acids (MCFA) are potential biomarkers of milk production in other settings. This study investigates MCFA as markers of exclusive breastfeeding in low-and middle-income countries. This was an ancillary observational analysis of human milk fatty acids from a parent randomised controlled trial of vitamin D supplementation in Bangladesh. We categorised mothers as currently exclusively or non-exclusively breastfeeding based on weekly infant feeding questionnaires. We analysed milk fatty acids at 3 months postpartum by GC and modelled longitudinal exclusive breastfeeding using milk fatty acids in repeated-measures Poisson regression. Fatty acids are reported as % total fatty acids. The prevalence of currently exclusive breast-feeding was 76 % at 3 months and 43 % at 6 months (n 587). Both C6:0 and C15:0 were higher with exclusive breastfeeding (C6:0, P = 0·001; C15:0, P = 0·007), while C12:0 and C14:0 were lower (C12:0, P < 0·001; C14:0, P < 0·001). We combined these into an MCFA index defined as ((C6:0 + C15:0)/(C12:0 + C14:0)) × 1000 (Excl: 25 ± 0·50, Non-excl: 20 ± 0·60, P < 0·001). Mothers in the highest and lowest MCFA index tertiles had an exclusive breastfeeding prevalence at 3 months of 95 % and 60 %, respectively (P < 0·001), and remained different until 6 months. In secondary analysis, vitamin D supplementation during lactation was moderately associated with exclusive breastfeeding (relative prevalence: 1·17 (95 % CI 1·04, 1·32)). Milk MCFA were markers of exclusive breastfeeding in this cohort, and the milk MCFA index at 3 months predicted exclusive breastfeeding from 3 to 6 months postpartum.

Despite increasing efforts to promote and support breastfeeding, the United States continues to have some of the lowest exclusive and sustained breastfeeding rates globally. Foreign-born immigrants and refugees specifically have been reported to have high initiation but low exclusive breastfeeding (EBF) rates. This scoping review aims to explore what is known about strategies to support breastfeeding among foreign-born mothers in the United States using the Arksey & O’Malley framework for scoping reviews and PRISMA-ScR (Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews). Six databases were searched using a comprehensive search strategy and 2103 articles were identified, of which 31 met eligibility criteria and discussed 33 specific breastfeeding interventions. The articles describe a range of interventions, including breastfeeding promotion and education (n = 30), hands-on breastfeeding support (n = 9), material support like giving breastfeeding supplies and food (n = 16), social support (n = 18) and social marketing campaigns (n = 1) to promote community support for breastfeeding. Common strategies for implementing these interventions include individual counselling (n = 21), group breastfeeding education (n = 17), informational materials (n = 12) and family support promotion (n = 11). In total, 87·3% of the immigrant mothers targeted by these breastfeeding support interventions were Hispanic, and 4·5% and 7·0% were mothers of African and Asian descent, respectively. This study reveals limited data and key gaps in efforts to preserve the culture of breastfeeding and promote EBF among multicultural immigrant and refugee families, particularly non-Hispanic groups. Addressing these gaps will improve optimal infant feeding practices among foreign-born mothers in the United States and, consequently, maternal and infant health outcomes.

The distinct size and shape of breasts in women is a uniquely human trait. This trait has no conclusive explanation as it is not a requirement for milk production. Additionally, breasts are already enlarged at puberty, which is usually long before the first pregnancy. We hypothesized that the perennially enlarged human breasts were potentially developed to support infant’s thermal balance by providing increased warming surface in skin-to-skin contact.

To test the hypothesis, we measured breast surface temperature to explore their heating capacity and resilience to temperature changes in an environmental conditions laboratory. Volunteers, divided in groups of nursing women, non-nursing women, and men, were exposed to three temperatures: 32°C, 27°C, and 18°C. The exposure time in each temperature was 20 min. The changes in breast surface temperature were recorded by thermal imaging camera. Data were analysed using Kruskal–Wallis tests. Breastfeeding women had overall higher mammary surface temperature compared to other groups. Furthermore, nursing women had distinct resilience against cooling environment: they lost the average of 2.5°C of their mammary surface temperature, whereas other study groups lost 4.3°C and 4.7°C of surface temperature, respectively. This proof-of -concept study clearly indicated the potential of the nursing women’s breasts to support infant’s thermal balance.

Pregnancy and lactation change women’s body composition (BC), but few longitudinal studies have investigated postpartum BC trajectories. We aimed to investigate maternal and infant predictors of maternal body fat (BF), fat mass (FM), fat-free mass (FFM) and BMI trajectories during lactation. Longitudinal study with 234 Brazilian mother–infant dyads followed at 1·0–3·49, 3·5–5·99 and 6·0–8·5 months postpartum. Maternal BC was estimated using bioelectrical impedance at all follow-up points. Longitudinal mixed–effects models with interaction terms with time (weeks postpartum) were employed. FFM declined significantly over weeks postpartum (β = −0·02 kg; 95 % CI –0·03, −0·01). Pre-pregnancy overweight women experienced an increase in all body components (BF: β = 4·91 %, 95 % CI 3·79, 6·04; FM: β = 6·46 kg, 95 % CI 5·26, 7·67; FFM: β = 3·72 kg, 95 % CI 2·80, 4·65) and BMI (β = 4·51 kg/m2, 95 % CI 3·91, 5·12). Multiparous women showed BMI increases (β = 0·76 kg/m2, 95 % CI 0·11, 1·41), and those who delivered by caesarean had FFM (β = 1·87 kg, 95 % CI 0·67, 3·07) and BMI (β = 1·39 kg/m2, 95 % CI 0·61, 2·18) increases. Women who birthed girls had reductions in FM (β = −1·24 kg, 95 % CI –2·41, −0·07) and FFM (β = −0·93 kg, 95 % CI –1·84, −0·01). Interactions occurred between maternal age ≥ 30 years, higher family income, multiparity and infant sex for BC and BMI trajectories. Maternal age, pre-pregnancy BMI, parity, family income, mode of delivery and infant sex predict maternal BC and BMI trajectories.

The objective was to evaluate the influence of supplementation of L-arginine at 10 g/kg on the performance of lactating sows and their litters by evaluating the milk amino acid composition, serum hormone levels, mammary tissue redox status indicators, mammary tissue histomorphology, and the expression of genes related to mammary gland metabolism. The study was conducted in the municipality of Oliveira, Minas Gerais, Brazil, in 2019. A total of 24 sows were selected. A completely randomized design was used in a 2 × 3 factorial arrangement, with two diets (control and 10 g L-arginine/kg) and three mammary gland positions (thoracic, abdominal and inguinal), totaling six treatment groups. Each dietary treatment consisted of 12 replicates, with each replicate equivalent to one experimental unit, which was considered a sow and its litter. Females that were fed a diet supplemented with L-arginine had lower feed intake and greater weight loss. Piglets from sows that received L-arginine supplementation presented reduced weaning weight variation. L-arginine supplementation did not affect the amino acid composition of the milk, the plasma hormone levels of the sows, the oxidative stress parameters of redox, or breast tissue morphology. However, it may modulate the expression of genes important for mammary gland metabolism, such as the COX1 and SLC27A4. Piglets that suckled teats in the thoracic and abdominal positions had higher mean weights at 14 and 23 days, as well as greater daily weight gains. L-arginine supplementation to sows improves litter quality by increasing weaning weight uniformity; piglets that occupy the thoracic and abdominal positions perform better.

We have previously demonstrated that calcium plus vitamin D supplementation during adolescent pregnancy reduces the magnitude of transient postpartum bone mass loss. In the present post hoc analysis, we further investigated the effect of calcium plus vitamin D supplementation during pregnancy in hip geometry throughout one year postpartum in Brazilian adolescents with low daily calcium intake (∼600 mg/d). Pregnant adolescents (14–19 years) were randomly assigned to receive calcium (600 mg/d) plus vitamin D3 5 μg/d (or 200 IU/d) or a placebo from 26 weeks of gestation until parturition. Dual-energy X-ray absorptiometry images were obtained at 5 (n 30 and 26 for calcium plus vitamin D and placebo, respectively), 20 (n 26 and 21) and 56 (n 18 and 12) weeks postpartum, and hip geometry parameters were analysed by Advanced Hip Assessment software. The effects of the intervention, time point and their interaction were assessed using repeated-measures mixed-effects models. No significant intervention effects or intervention × time interactions were observed on hip geometry parameters (P > 0·05). Time effects were observed in cross-sectional area, cross-sectional moment of inertia and section modulus parameters with decreases from the 5th to the 20th week postpartum followed by recovery from the 20th to the 56th week (P < 0·05). Our findings indicate that the postpartum period is associated with transient changes in the hip geometry of lactating adolescent mothers, regardless of the low calcium intake and the supplementation offered during pregnancy, suggesting that a physiological adaptation of these adolescents to low calcium intake is at play.

This scoping review addresses gaps in the existing literature on dietary guidelines for pregnant and lactating women globally. The study delves into adherence levels, identifies influencing factors and examines outcomes associated with these guidelines. Analysing food-based dietary guidelines (FBDG) from around the world, the review reveals that half of the countries lack FBDG, with only 15% providing tailored advice for pregnant and lactating women. Utilising data extracted from forty-seven articles across MEDLINE and EMBASE, the study highlights a scarcity of adherence studies, particularly in low- or middle-income countries (LMIC), and emphasises the lack of research during lactation. Overall adherence to dietary guidelines is low, with disparities in fruit, vegetable, whole grain and fish consumption. Positive correlations with adherence include age, education, employment, social class and certain medical histories, while negative correlations involve smoking, alcohol consumption, metropolitan residence and elevated BMI. The study documented significant associations between adherence and reduced risks of gestational complications but calls for further exploration of intermediate nutritional outcomes such as micronutrient deficiencies and child growth. Emphasising the urgency for globally standardised guidelines, especially in LMIC, this review provides a foundational call for prioritised studies and strategies to enhance dietary practices for pregnant and lactating women worldwide.

The developmental origins of health and disease hypothesis have highlighted the link between early life environment and long-term health outcomes in offspring. For example, maternal protein restriction during pregnancy and lactation can result in adverse metabolic and cognitive outcomes in offspring postnatal. Hence, in the present study, we assess whether an isocaloric low-protein diet (ILPD) affects the fatty acid profile in breast milk, the hippocampal synaptophysin (Syn) ratio, and the oxidative stress markers in the neonatal stage of male and female offspring. The aim of this work was to assess the effect of an ILPD on the fatty acid profile in breast milk, quantified the hippocampal synaptophysin (Syn) ratio and oxidative stress markers in neonatal stage of male and female offspring. Female Wistar rats were fed with either a control diet or an ILPD during gestation to day 10 of lactation. Oxidative stress markers were assessed in serum and liver. All quantifications were done at postnatal day 10. The results showed: ILPD led to decreases of 38.5% and 17.4% in breast milk volume and polyunsaturated fatty acids content. Significant decreases of hippocampal Syn ratio in male offspring (decreases of 98% in hippocampal CA1 pyramidal and CA1 oriens, 83%, stratum pyramidal in CA3, 80%, stratum lucidum in CA3, and 81% stratum oriens in CA3). Male offspring showed an increase in pro-oxidant status in serum and liver. Thus, the data suggest that male offspring are more vulnerable than females to an ILPD during gestation and lactation.

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.

We previously reported changes in gene expression in mammary tissue from non-inflamed mammary glands adjacent to an inflamed gland challenged with lipopolysaccharide (LPS). We determined if changes in the expression of selected genes in non-inflamed glands would be replicated in RNA isolated from milk fat. Cows were milked twice daily prior to experiment. Per cow, one mammary gland (QLPS) was randomly assigned to receive an intramammary infusion of 50 µg LPS immediately after morning milking on d-0. The ipsilateral (QI) and contralateral (QC) mammary glands adjacent to QLPS remained untreated. Quarter foremilk samples from all mammary glands were collected on d-1 and d-0 for milk composition and isolation of RNA for quantification of selected genes via quantitative polymerase chain reaction. Symptoms of clinical mastitis developed only in QLPS and were apparent within 3 h post-challenge. In QI and QC, lactose percentages were lower at 12 h post-challenge compared to d-1, but milk fat and protein contents were not different. For gene expression, 7 of 13 selected genes were differentially regulated in non-inflamed glands. In QI but not QC, LALBA expression was lower at 12 h post-challenge than on d-1. One gene of interest, LPIN1, was significantly upregulated in QI and QC but downregulated in QLPS at 12 h post-challenge. Five additional immune or stress-related genes were significantly upregulated in QLPS and, to a lesser but significant degree, in QI and QC compared to d-1. Notably, expression of two immune genes (NFKBIA, PTX3) was significantly greater in QI than QC despite QI having a numerically lower somatic cell count. Minor changes in the composition of milk secreted by non-inflamed mammary glands were linked to several immune and stress responses in those glands. Further, individual non-inflamed mammary glands responded differently depending on their position relative to the mastitic gland.

Our objectives were to quantify the dimensions of a fully ‘closed’ teat canal in dry cows and to describe recovery of the teat canal between milkings in lactating cows to assess whether and when full closure is attained, since this is an important determinant of udder health. Using an ultrasound scanner, teat canal length and diameter (proximal, midpoint and distal), teat cistern width, teat end width, whole teat width and teat wall thickness in 77 dry and 39 lactating dairy cows were measured. The dry cows represented a cross section of the dry population, with days since dry off ranging from 0 to 69 (median: 27). Data from lactating cows were recorded just before milking, and every 3 h post-milking. To control for location a cross-over (parlour vs. barn) study design was used. In dry cows, teat canal length and diameter did not vary by quarter or days since dry off, but multiparous cows had significantly wider teat canals than primiparous cows. The dry cow measurements can be used as baseline for dimensions for closed teats. In lactating cows, all teat dimensions except teat end width changed significantly during the 12-h milking cycle. Location (parlour vs. barn) did not affect the measurements, except teat end width and teat wall thickness. Teat canal length increased after milking and returned to pre-milking values by 9 h. Proximal and midpoint teat canal diameters decreased slightly just after milking and then progressively increased to above the pre-milking values by 9 h. Distal teat canal diameter increased after milking, partially contracting by 9 h. We found that during the dry period the teat canal is in a steady state, but its diameter is not zero, while during the lactation, the teat canal is in a near constant state of remodelling.