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The composition of human milk is influenced by storage and processing practices. The effects of thawing and warming practices on human milk composition remain poorly studied despite their prevalence in home, research, and donor milk bank settings. This review comprehensively examines the impact of different thawing and warming methods on nutritional and bioactive human milk components. While some components such as carbohydrates and minerals remain stable under most typical thawing and warming conditions, others, such as fat, immune proteins, bacterial and human cells, and peptide amine hormones, are sensitive to warming. This review has identified that the data on the effects of milk thawing and warming is limited and often contradictory. Given that numerous important components of milk are diminished during cold storage, it is important that thawing and warming practices do not lead to further loss of or alterations to beneficial milk components. Further work in this field will facilitate greater standardization of thawing methods among researchers and underpin recommendations for thawing and warming of expressed milk for parents.

Objective:Human milk (HM) sodium (Na) and potassium (K) concentrations, as well as the Na and K ratio (Na:K), are associated with stages of lactation and breast health. Portable point-of-care instruments to measure HM biomarkers related to secretory activation or tight junction disturbances would supply clinicians immediate information for individualized lactation care. This study compared HM concentrations of Na and K and Na:K measured by a biochemist with inductively coupled plasma optical emission spectrometry (ICP-OES) and measured by a clinician with ion-selective electrode probes (ISEPs).Design:HM samples (n= 92) were participant collected and donated on day 10 postpartum through a convenience sample of breastfeeding women in West Michigan. Na and K concentrations were determined using ICP-OES and ISEPs. Bland–Altman plots, paired sample t-test, and logistic regressions were completed using R 3.4.4 and R Studio 1.2.1335 with package Lattice.Results:Na concentrations were not significantly different with ICP-OES (13.0 ± 14.8 mM) and ISEPs (12.6 ± 13.7 mM, p= 0.06), whereas K concentrations (ICP-OES 16.1 ± 1.9 mM, ISEPs 14.4 ± 2.4 mM, p< 0.001) and Na:K (ICP-OES 0.81 ± 0.92, ISEPs 1.01 ± 1.62, p= 0.011) were significantly different. Between both methods, the Na, K, and Na: K linear relationships were statistically significant.Conclusion:With additional longitudinal and clinical usefulness research clinicians could use ISEPs to collect and interpret relevant lactation data to support individualized lactation interventions.

Background:Nipple pain is a common cause of early cessation of breastfeeding. A nipple shield (shield) is often used to improve breastfeeding comfort. There are concerns that shield use may limit milk transfer. The aims of this study were to determine whether shield use reduces milk transfer and maternal nipple pain.Methods:A within-subject study of two groups of breastfeeding dyads (infants <6 months) was conducted; Control Group (CG): no breastfeeding difficulties; Pain Group (PG) shield used for nipple pain. There were two monitored sessions where shield use was randomized. Test weights and pain questionnaires were completed, and percentage of available milk removed (PAMR) was calculated.Results:Twenty-five PG (6 ± 4 postnatal weeks) and 34 CG (9 ± 6 postnatal weeks) had similar 24-hour milk production (PG: 676 ± 239 mL, CG: 775 ± 162 mL, p= 0.083). PG mean milk transfer volume and PAMR did not differ with shield use (no shield: 46 mL, 59%; shield: 40 mL, 53%, volume p= 0.38, PAMR p= 0.64). CG mean volume and PAMR were reduced with shield use (no shield: 65 mL, 64%; shield: 31 mL, 33%, volume p< 0.001, PAMR p< 0.001). PG pain scores were similar with and without shield use (Visual Analog Scale p= 0.44, McGill p= 0.97).Conclusions:Shield use did not impact either milk production or milk transfer in breastfeeding women experiencing nipple pain.

AbstractIntroduction:S. aureusis one of the most prevalent potential pathogenic bacteria found in DHM. Some strains produce heat stable enterotoxins that are able to survive pasteurization. These enterotoxins have been associated with gastritis and potentially necrotizing enterocolitis in preterm infants. The aim of this study is to assess the impact of different storage temperatures on Staphylococcus aureusgrowth and enterotoxin A and B production in raw and Holder pasteurized donor human milk (DHM).Materials and Methods:Raw and pasteurized DHM were inoculated with enterotoxin A and B producing S. aureus. Samples were incubated at 4°C (10 days), 21°C, and 37°C (18 hours). Bacterial growth and enterotoxin A and B were quantified.Results:S. aureuscount increased in pasteurized DHM. Bacterial count decreased in the raw milk when incubated at 21°C and 4°C and slightly increased when incubated at 37°C. Enterotoxins A and B were only detected in pasteurized DHM at 37°C from 9 hours onward.Conclusion:This study showed that raw milk is capable of suppressing S. aureusgrowth compared to pasteurized DHM. It also provides a measure of assurance of the safety of raw and pasteurized DHM when refrigerated or left at room temperature for a few hours.

AbstractBackground:Some strains of Staphylococcus aureuscan produce heat-stable enterotoxins that have been associated with gastritis and potentially necrotizing enterocolitis in preterm infants.Objectives/Hypothesis:To assess the impact of different storage temperatures on S. aureusgrowth and enterotoxin production in raw, Holder-pasteurized (HP) and ultraviolet-C (UV-C)-treated donated human milk (DHM).Materials and Methods:The milk samples from individual donors were pooled and divided into four equal portions. One portion was HP, the second was UV-C treated, the third was not treated, and the fourth was UV-C treated after being spiked with S. aureus. All samples were incubated at 37°C (18 hours) and 4°C (14 days). Bacterial colony count, enterotoxin A and B, and immune proteins were quantified.Results:At 37°C, the colony count increased in HP DHM and decreased in raw and UV-C-treated DHM. At 4°C, colony counts in HP DHM reduced and were not detected in raw and UV-C-treated DHM from day 8 of incubation. No bacteria were detected in samples that were inoculated before UV-C treatment. Enterotoxin A was only detected in HP-DHM at 37°C from the 9th hour onward. Enterotoxin B was detected in one sample at the 15th hour. Immune protein concentrations were similar in raw and UV-C DHM, and were reduced in the HP DHM.Conclusion:UV-C-treated milk reduces S. aureusgrowth with similar kinetics to raw milk making it a promising emerging technique to eliminate bacteria while retaining essential immune proteins in DHM.

The development of the breast for lactation occurs throughout pregnancy. It is unknown whether pregnancy complications resulting in poor fetal growth can affect breastfeeding success.

Low milk supply (LMS) poses a significant challenge to exclusive and continued breastfeeding, affecting ∼10% to 15% of mothers. Milk production is intricately regulated by both endocrine and autocrine control mechanisms, with estrogens and progesterone playing pivotal roles in this process. In addition to endogenously produced hormones, external substances capable of interfering with normal hormonal actions, including phytoestrogens, mycoestrogens, synthetic estrogens, and hormonal contraceptives, can influence milk production. The effects of these extrinsic hormones on milk production may vary based on maternal body mass index. This comprehensive review examines the multifaceted causes of LMS, focusing on the involvement of estrogens, progesterone, and related external factors in milk production. Furthermore, it investigates the interplay between hormonal factors and obesity, aiming to elucidate the endocrine mechanisms underlying obesity-associated LMS. Insights from this review provide valuable perspectives for developing interventions to improve milk production and address the challenges associated with LMS.

AbstractObjective:Mothers of premature infants confront barriers to coming to volume (CTV; ≥500 mL/day mother's own milk [MOM] by postpartum day 14), a strong predictor of continued MOM provision at neonatal intensive care unit (NICU) discharge. We sought to determine concentrations of secretory activation biomarkers (MOM sodium, total protein, lactose, and citrate) during the first 14 postpartum days and to describe relationships among these biomarkers, pumped MOM volume, CTV, and pumping frequency.Study Design:This descriptive observational study collected serial MOM samples, pumped MOM volume, and pumping frequency during the first 14 postpartum days in 16 breast pump-dependent mothers who delivered <33 weeks gestation. Daily biomarker concentrations were compared to published normal values for mothers of term infants. Relationships among biomarkers, pumped MOM volume, and pumping frequency were determined.Results:On postpartum day 5, only 40% of MOM samples revealed normal concentrations of all four biomarkers, and normalcy was not maintained throughout the first 14 days. All eight mothers (50%) who achieved CTV had normal concentrations for four biomarkers at 5.4 ± 3.5 days postpartum and had more cumulative pumping sessions by day 5 (p= 0.03). A dose–response relationship between number of normal biomarkers and pumped MOM volume was demonstrated for postpartum days 3 (p= 0.01) and 5 (p= 0.04).Conclusion:Secretory activation is delayed in mothers who deliver prematurely and is closely tied to CTV, MOM volume, and pumping frequency. MOM biomarkers hold promise as objective research outcome measures and for point-of-care testing to identify and proactively manage mothers at risk for compromised lactation.

To improve convenience and maximize flexibility whilst pumping, wearable pumps have been designed however, their performance have not been evaluated. This study aimed to develop the protocol and evaluate the efficacy and comfort of a new hands-free, in-bra, breastmilk collection pump set (IBCPS) connected to a personal use double electric breast pump.

The mammary gland undergoes significant remodeling during pregnancy and lactation, which is fuelled by controlled mammary stem cell (MaSC) proliferation. The scarcity of human lactating breast tissue specimens and the low numbers and quiescent state of MaSCs in the resting breast have hindered understanding of both normal MaSC dynamics and the molecular determinants that drive their aberrant self‐renewal in breast cancer. Here, we demonstrate that human breastmilk contains stem cells (hBSCs) with multilineage properties. Breastmilk cells from different donors displayed variable expression of pluripotency genes normally found in human embryonic stem cells (hESCs). These genes included the transcription factors (TFs) OCT4, SOX2, NANOG, known to constitute the core self‐renewal circuitry of hESCs. When cultured in the presence of mouse embryonic feeder fibroblasts, a population of hBSCs exhibited an encapsulated ESC‐like colony morphology and phenotype and could be passaged in secondary and tertiary clonogenic cultures. While self‐renewal TFs were found silenced in the normal resting epithelium, they were dramatically upregulated in breastmilk cells cultured in 3D spheroid conditions. Furthermore, hBSCs differentiated in vitro into cell lineages from all three germ layers. These findings provide evidence that breastmilk represents a novel and noninvasive source of patient‐specific stem cells with multilineage potential and establish a method for expansion of these cells in culture. They also highlight the potential of these cells to be used as novel models to understand adult stem cell plasticity and breast cancer, with potential use in bioengineering and tissue regeneration. STEMCells2012;30:2164–2174

AbstractAim:Breastfeeding mothers expressed their breasts hourly for periods up to 7 hours, without exogenous oxytocin, to determine the consistency of milk removal and the relationship between the volume of milk removed and the mother's 24-hour milk production.Methods:Mothers (n= 20) measured their 24-hour milk production from each breast by test-weighing their babies at home. Mothers came to the research laboratory for a day visit and expressed milk from either both or one breast (left or right) for 10–15 minutes, every hour for 2–7 hours. Mothers were not instructed to restrict breastfeeding prior to the first (0-hour) expression.Results:It was found that the milk volume at 1 hour (59.7 ± 36.5 and 46.5 ± 25.6 mL/hour for the right and left breast, respectively) was significantly (p< 0.05) higher than the milk volume from subsequent hourly intervals. The average hourly volumes obtained from the 2ndto 7thhour (18.0 ± 3.1 and 14.0 ± 4.8 mL/hour for the right and left breast, respectively) were not significantly different from the average hourly rates calculated for the 24-hour milk production (18.4 ± 6.3 and 15.5 ± 5.1 mL/hour for the right and left breast, respectively). Furthermore, local inhibition was not observed during hourly expressions of up to 7 hours.Conclusion:The average hourly volumes of milk from the 2ndto 7thhour expressions could provide an estimate of the rate of milk secretion. Further study is required to fully validate these findings.

The authors compared milk expession using 5 experimental vacuum patterns and a commercially available vacuum pattern ranging in cycle times (20 to 78 cycles/min) and vacuum curve dynamics in 30 mothers using an experimental, software-controlled electric breast pump. The volume of milk removed over 5 minutes differed (P= .0072) between patterns (range = 62.8 ± 6.6m Lto 47.2 ± 5.1 mL). However, therewas no difference in the percentage of available milk removed (range = 99.4% ± 15.1% to 70.6% ± 8.6%). The rate of milk removal differed between patterns at both the beginning (1 minute) and end (1.5 minutes) of the expression period (P< .05). Peak vacuum chosen differed between patterns (P= .0085) butwas not related to either the volume or percentage of available milk expressed. Breastfeeding characteristics did not differ between poor and successful expressers. These results showthat breast milk expression by an electric breast pump can be influenced by the vacuum pattern.

The authors compared breastfeeding and expression characteristics in 30 mothers of exclusively breastfeeding, healthy term infants. Mean (± SD)volume per breastfeed from one breast was 71.8 ± 26.3 mL, and mean duration per breastfeed for one breastwas 16.6 ± 10.5 minutes. Mean volume of milk expressed in 5 minutes from one breast was 60.6 ± 39.0 mL and corresponded to the expression of 99.4 ± 82.6% of the milk stored in the breast. The rate of milk expression differed greatly between mothers (P= .0001)b ut remained constant for the first 2.5 minutes before decreasing with time (P= .0001). These results show the mean breastfeed volumewas similar to the volume of milk expressed in a 5-minute period. Furthermore, this study is the first to establish protocols that allow for the objective determination of breast pump efficacy.

Introduction:This prospective longitudinal study examined changes in milk sodium concentration (Na) and sodium:potassium ratio (Na:K), microbiological culture, milk production, and breast health in relation to mastitis after preterm birth.Methods:We studied women who gave birth at 29–34 weeks of gestation in a tertiary obstetric hospital in Perth, Western Australia. Milk samples, 24-hour milk production, and breast health data were collected every second day to day 10 postpartum, then every third day until infant discharge from the neonatal unit. Milk Na and K were measured at point of care (POC) using handheld ion selective meters, and Na:K calculated. Cultures were performed on postnatal days 8, 13, and every 6 days thereafter. For episodes of mastitis, milk was cultured at onset, and Na and Na:K measured daily until resolution. Women were followed up at 4 and 8 weeks postpartum.Results:In a sample of 44 women, 4 mastitis cases were detected in 3 women during their infants' neonatal stay; all had elevated milk Na and Na:K that resolved within 48 hours; 2/4 experienced reduced milk production and 1/4 had heavy growth of Staphylococcus epidermidis. A further 2 mastitis cases were reported in 39 women followed up to 8 weeks postpartum. Four women had elevated milk Na and Na:K without clinical signs of mastitis; three also had reduced milk production.Conclusions:POC testing of milk Na and/or Na:K may offer a useful indicator of breast health. Mastitis may cause an acute reduction in milk production regardless of the presence of culture-positive infection.