The Relation between Breast Milk Sodium to Potassium Ratio and Maternal Report of a Milk Supply Concern

Breast milk Na+ and Na+/K+ ratio predict delayed onset of lactogenesis in gestational hyperglycemia

To investigate the predictive value of breast milk Na+ concentration and Na+/K+ ratio on delayed onset of lactogenesis (DOL) in puerpera with gestational hyperglycemia. Puerpera with gestational hyperglycemia who delivered at The First Affiliated Hospital of Army Medical University in China between October 20, 2023, and April 1, 2024, were enrolled. The concentrations of Na+ and K+ in breast milk samples were examined from study participants on days 1-3 of the postpartum period. The predictive value of Na+ concentration and the Na+/K+ ratio on DOL were assessed using receiver operating characteristic (ROC) curves. Both the Na+ concentration and Na+/K+ ratio in breast milk collected on day 3 could effectively predict DOL, with areas under the curve (AUCs) of the ROC curve and 95%CI values of 94.7% (95%CI = 0.901-0.992) and 94.2% (95%CI = 0.890-0.994), respectively. The optimized cutoffs were Na+ concentration ≥ 26.25 mmol/L (sensitivity = 88.2%, specificity = 92.2.8%) and Na+/K+ ratio ≥ 1.646 (sensitivity = 79.4%, specificity = 98.4%). Both the Na⁺ concentration and Na+/K+ ratio in breast milk were found to be effective in predicting DOL in puerpera with gestational hyperglycemia.

Feasibility of Using Point-of-Care Biomarkers of Secretory Activation to Address Early, Unplanned Weaning Among Healthy, Term Dyads in Community Settings: A Pilot Study

Background: Delayed and/or impaired secretory activation (SA) achievement is a risk factor for early unplanned lactation cessation. This pilot study (1) evaluated the feasibility of in-home daily milk collection; (2) compared daily maternal self-report of breast fullness with mother's own milk (MOM) biomarkers of SA; and (3) examined SA patterns in association with lactation outcomes through 3 months postpartum. Methods: Twelve mother-infant dyads were enrolled at term (median gestational age (GA) = 39.9 weeks, range = 38.3-41.1 weeks). After birth, participants self-reported breast fullness and collected milk samples daily for a week. Infant weight gain and milk intake by test-weights were assessed postpartum during a week 1 routine infant outpatient visit and again during a week 2 home visit. Milk samples were tested for sodium (Na) and potassium (K) using portable ion selective electrodes. Timing of SA achievement was denoted as the first day breast fullness was self-rated ≥ 3, Na concentration was < 12 mmol/L, or the Na/K ratio was < 0.6. Breastfeeding duration and exclusivity were measured at 1, 2, and 3 months postpartum. Results: By day 6, all mothers self-reported SA achievement, while only 72-82% achieved SA using MOM biomarkers. Cohen's kappa between the timing of SA by maternal self-report and MOM biomarkers showed lack of agreement (κ = 0.05 and 0.08), but was high between MOM Na and Na/K ratio (κ = 0.87). Three patterns of SA by MOM biomarkers emerged (mature and stable, impermanent, and delayed) with implications for infant weight loss/gain at 1 week postpartum. These patterns were not associated with breastfeeding exclusivity through 3 months postpartum in this highly motivated sample. Conclusion: MOM biomarkers of SA achievement are feasible and have significant potential for use in community settings.

The prospective associations of fetal growth-related pregnancy complications with subsequent breastfeeding duration and markers of human milk production

BACKGROUND

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

OBJECTIVES

We examined whether fetal growth-related pregnancy complications were associated with earlier BF cessation and changes in the concentrations of human milk biomarkers of low milk production.

METHODS

We used data from the Growing Up in Singapore Toward healthy Outcomes study (n = 954). Human milk concentrations of protein, lactose, citrate, sodium, potassium, and zinc at 3 wk postpartum were available for 180 mother-infant dyads. We examined the associations of fetal growth measures, including term infants born small-for-gestational-age (SGA) (<10th percentile), pregnancies complicated by fetal growth deceleration (second to third trimester fetal growth dropped between major centiles), elevated umbilical artery resistance (>90th percentile) or hypertensive disorders of pregnancy (HDP) with 1) risk of ceasing BF (Cox regression) and 2) concentrations of human milk components (weighted linear regression).

RESULTS

Adjusting for maternal education, smoking exposure, BF intentions, and prepregnancy BMI (in kg/m2), individuals who delivered SGA infants and those with HDP were more likely to breastfeed for a shorter duration when compared to those with uncomplicated pregnancies {adjusted hazard ratio [95% confidence interval (CI)]: 1.45 (1.11, 1.89) and 1.61 (1.14, 2.29), respectively}; associations were nonsignificant for fetal growth deceleration and umbilical artery resistance. SGA was not associated with concentrations of human milk biomarkers, but compared to participants with uncomplicated pregnancies, milk produced by those with HDP contained lower zinc concentrations [adjusted β coefficient (95% CI): -0.56 mg/L (-1.08, -0.04) mg/L].

CONCLUSIONS

Individuals with HDP and those with SGA infants tend to breastfeed for a shorter duration; however, only HDP appear to be associated with biomarkers of compromised milk production. Further research and support are needed to help individuals with HDP and SGA achieve their BF goals. This trial was registered at clinicaltrials.gov as NCT01174875.

A handheld milk conductivity sensing device (Mylee) for measuring secretory activation progress in lactating women: a device validation study

BACKGROUND

Human milk electrolytes are known biomarkers of stages of lactation in the first weeks after birth. However, methods for measuring milk electrolytes are available only in laboratory or expert settings. A small handheld milk sensing device (Mylee) capable of determining on-site individual secretory activation progress from sensing the conductivity of a tiny milk specimen was developed. Here we evaluate the validity of a novel milk-sensing device (Mylee) for measuring the progress of milk maturation and secretory activation status.

METHODS

Retrospective data analysis of laboratory records generated using the Mylee device. Device conductivity measurements were assessed for accuracy, reliability and stability in rigorous laboratory tests with standard materials. A set of human milk specimens (n = 167) was used to analyze the agreement between the milk maturation score and laboratory measurements of the secretory activation biomarker milk sodium [Na+].

RESULTS

The Mylee device was demonstrated to have excellent reproducibility (CV95%<5%) and accuracy (error < 5%) for conductivity measurements of a small specimen (350 µl), with good device stability and almost perfect inter-device unit reliability (ICC > 0.90). With regression analysis, we revealed excellent agreement between Mylee milk maturation (MM%) output or its raw conductivity signal and laboratory measurements of conductivity and sodium [Na+] in a dataset of milk specimens (n = 167; R2 > 0.9). The Mylee MM% score showed good predictive ability for secretary activation status, as determined by sodium threshold (18 mmol/L) in human milk specimens.

CONCLUSIONS

In this study, we demonstrated the reliability and validity of the Mylee device and its ability to detect on-site milk secretory activation in a manner comparable to that of electrolyte-based methods. The novel MyLee device offers the potential to generate real-time information about the lactation stage, measured by mothers at the commodity of their home.

Milk Composition Is Predictive of Low Milk Supply Using Machine Learning Approaches

Background/Objectives: The causes of low milk supply are multifactorial, including factors such as gene mutations, endocrine disorders, and infrequent milk removal. These factors affect the functional capacity of the mammary gland and, potentially, the concentrations of milk components. This study aimed to investigate the differences in milk composition between mothers with low and normal milk supply and develop predictive machine learning models for identifying low milk supply. Methods: Twenty-four-hour milk production measurements were conducted using the test-weigh method. An array of milk components was measured in 58 women with low milk supply (<600 mL/24 h) and 106 with normal milk supply (≥600 mL/24 h). Machine learning algorithms were employed to develop prediction models integrating milk composition and maternal and infant characteristics. Results: Among the six machine learning algorithms tested, deep learning and gradient boosting machines methods had the best performance metrics. The best-performing model, incorporating 14 milk components and maternal and infant characteristics, achieved an accuracy of 87.9%, an area under the precision-recall curve (AUPRC) of 0.893, and an area under the receiver operating characteristic curve (AUC) of 0.917. Additionally, a simplified model, optimised for clinical applicability, maintained a reasonable accuracy of 78.8%, an AUPRC of 0.776, and an AUC of 0.794. Conclusions: These findings demonstrate the potential of machine learning models to predict low milk supply with high accuracy. Integrating milk composition and maternal and infant characteristics offers a practical approach to identify women at risk of low milk supply, facilitating timely interventions to support breastfeeding and ensure adequate infant nutrition.

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.

Mammary epithelium permeability during established lactation: associations with cytokine levels in human milk

Objective

The cytokine profile of human milk may be a key indicator of mammary gland health and has been linked to infant nutrition, growth, and immune system development. The current study examines the extent to which mammary epithelium permeability (MEP) is associated with cytokine profiles during established lactation within a sample of US mothers.

Methods

Participants were drawn from a previous study of human milk cytokines. The present analysis includes 162 participants (98 Black, 64 White) with infants ranging from 1 to 18 months of age. Levels of cytokines were determined previously. Here we measure milk sodium (Na) and potassium (K) levels with ion-selective probes. Two approaches were used to define elevated MEP: Na levels ≥10 mmol/L and Na/K ratios greater than 0.6. Associations between maternal-infant characteristics, elevated MEP, and twelve analytes (IL-6, IL-8, TNFα, IL-1β, FASL, VEGFD, FLT1, bFGF, PLGF, EGF, leptin, adiponectin) were examined using bivariate associations, principal components analysis, and multivariable logistic regression models.

Results

Elevated MEP was observed in 12 and 15% of milk samples as defined by Na and Na/K cutoffs, respectively. The odds of experiencing elevated MEP (defined by Na ≥ 10 mmol/L) were higher among Black participants and declined with older infant age. All cytokines, except leptin, were positively correlated with either Na or the Na/K ratio. A pro-inflammatory factor (IL-6, IL-8, TNFα, IL-1β, EGF) and a tissue remodeling factor (FASL, VEGFD, FLT1, bFGF, PLGF, adiponectin) each contributed uniquely to raising the odds of elevated MEP as defined by either Na or the Na/K ratio.

Conclusion

This exploratory analysis of MEP and cytokine levels during established lactation indicates that elevated MEP may be more common in US populations than previously appreciated and that individuals identifying as Black may have increased odds of experiencing elevated MEP based on current definitions. Research aimed at understanding the role of MEP in mammary gland health or infant growth and development should be prioritized.

Milk Biomarkers of Secretory Activation in Breast Pump-Dependent Mothers of Preterm Infants: An Integrative Review

Background: Lack of mother's own milk (MOM) at discharge from the neonatal intensive care unit (NICU) is a global problem and is often attributable to inadequate MOM volume. Evidence suggests that the origins of this problem are during the first 14 days postpartum, a time period that includes secretory activation (SA; lactogenesis II, milk coming in). Objectives: To describe and summarize evidence regarding use of MOM biomarkers (MBMs) as a measure of SA in pump-dependent mothers of preterm infants in the NICU and to identify knowledge gaps requiring further investigation. Methods: An integrative review was conducted using Whittemore and Knafl methodology incorporating the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) checklist. A search using electronic databases MEDLINE (through PubMed) and CINAHL (Cumulative Index to Nursing and Allied Health Literature) and reference lists of included articles was conducted. Results: Of the 40 articles retrieved, 6 met the criteria for inclusion. Results revealed the following five findings: (1) Achievement of SA defined by MBMs is delayed and/or impaired in mothers of preterm infants. (2) MBMs are associated with pumped MOM volume. (3) Achievement of SA defined by MBMs is associated with pumping frequency. (4) Delayed and/or impaired achievement of SA defined by MBMs may be exacerbated by maternal comorbidities. (5) There is a lack of consensus as to which MBM(s) and analysis techniques should be used in research and practice. Conclusions: MBMs hold tremendous potential to document and monitor achievement of SA in mothers of preterm infants, with multiple implications for research and clinical practice.

Novel At-Home Mother's Milk Conductivity Sensing Technology as an Identification System of Delay in Milk Secretory Activation Progress and Early Breastfeeding Problems: Feasibility Assessment

BACKGROUND

Prolonged exclusive breastfeeding is a public health priority and a personal desire by mothers; however, rates are low with milk supply challenges as a predominant cause. Early breastfeeding management at home is key. Milk electrolytes, mainly sodium ions, are accepted as biomarkers of secretory activation processes throughout the first weeks after birth and predictors for prolonged breastfeeding success, although they are not incorporated into routine care practice.

OBJECTIVE

The aim of this study was to test the feasibility of a novel handheld smartphone-operated milk conductivity sensing system that was designed to compute a novel parameter, milk maturation percent (MM%), calculated from milk sample conductivity for tracking individual secretory activation progress in a real-world home setting.

METHODS

System performance was initially evaluated in data collected from laboratory-based milk analysis, followed by a retrospective analysis of observational real-world data gathered with the system, on the spot in an at-home setting, implemented by lactation support providers or directly by mothers (N=592). Data collected included milk sample sensing data, baby age, and self-reported breastfeeding status and breastfeeding-related conditions. The data were retroactively classified in a day after birth-dependent manner. Results were compared between groups classified according to breastfeeding exclusivity and breastfeeding problems associated with ineffective breastfeeding and low milk supply.

RESULTS

Laboratory analysis in a set of breast milk samples demonstrated a strong correlation between the system's results and sodium ion levels. In the real-world data set, a total of 1511 milk sensing records were obtained on the spot with over 592 real-world mothers. Data gathered with the system revealed a typical time-dependent increase in the milk maturation parameter (MM%), characterized by an initial steep increase, followed by a moderate increase, and reaching a plateau during the first weeks postpartum. Additionally, MM% levels captured by the system were found to be sensitive to breastfeeding status classifications of exclusive breastfeeding and breastfeeding problems, manifested by differences in group means in the several-day range after birth, predominantly during the first weeks postpartum. Differences could also be demonstrated for the per-case time after birth-dependent progress in individual mothers.

CONCLUSIONS

This feasibility study demonstrates that the use of smart milk conductivity sensing technology can provide a robust, objective measure of individual breastfeeding efficiency, facilitating remote data collection within a home setting. This system holds considerable potential to augment both self-monitoring and remote breastfeeding management capabilities, as well as to refine clinical classifications. To further validate the clinical relevance and potential of this home milk monitoring tool, future controlled clinical studies are necessary, which will provide insights into its impact on user and care provider satisfaction and its potential to meet breastfeeding success goals.

The Utilization of Sodium Concentration in Human Milk from Pump-Dependent Mothers of Preterm Infants as a Measure of Milk Production

Objective: This study investigated changes in sodium concentrations in human milk from mothers of premature infants using different breast pumps for 14 days postpartum, and the correlation between the sodium concentration in mother's own milk (MOM) and the volume pumped. Study Design: This randomized controlled study recruited 66 mothers of premature infants delivered in our hospital from February to December 2018, and we assigned them to three groups using an envelope method. In intervention group 1, a hospital-grade electric breast pump was used from postpartum day 1 to 14; in intervention group 2, a hospital-grade electric breast pump was used on postpartum days 1 to 5 and a normal personal electric breast pump on postpartum days 6 to 14; in the control group, a personal normal electric breast pump was used from postpartum day 1 to 14. Data recorded included the breast milk volume pumped and milk sodium concentration. Results: The average daily volume of MOM pumped differed statistically (p < 0.05) between the intervention and control groups at postpartum days 7 and 14. The average daily volume pumped did not differ between intervention groups 1 and 2 by postpartum day 14 (p > 0.05). However, the time taken for the sodium concentrations to normalize differed significantly (p < 0.01). At postpartum day 5, the sodium concentrations of 73% of intervention group 1 and 2 mothers were within normal limits, and they were maintained until day 14. In comparison, only 41% of the controls had normal MOM sodium levels on day 5, and they were still high on day 7 in 27.3% of controls. Conclusions: In the early stage of lactation initiation (within 5 days postpartum), using a hospital-grade electric breast pump promotes lactation in mothers who deliver prematurely and the sodium concentrations normalize more quickly. Sodium can be used as an objective biomarker of MOM to evaluate the possibility of delayed lactation in mothers of premature infants, and it could assist interventions in the early postpartum period. Trial Registration: Chinese Clinical Trial Registry, ChiCTR2200061384.

Associations of Secretory Activation Breast Milk Biomarkers with Breastfeeding Outcome Measures

OBJECTIVE

The objective of this study was to explore associations between day 10 postpartum (D10) secretory activation biomarkers and the breastfeeding outcome measures.

STUDY DESIGN

This prospective longitudinal descriptive study collected antepartum, D10, and day 60 postpartum (D60) questionnaire data and D10 milk samples. Protein, lactose, and citrate were analyzed with enzymatic spectrophotometric assays. Sodium and potassium were analyzed with inductively coupled plasma optical emission spectrophotometry. Group comparison data were analyzed using χ², Fisher exact, and independent sample t tests, as appropriate, using SPSS for Mac (version 28).

RESULTS

Participants (n = 92) provided a D10 breastmilk sample and completed D10 questionnaires, and 83 completed D60 questionnaires. Participants with D10 impaired secretory activation sodium (>23.0 mM) were more likely to report D10 perceived insufficient milk supply, χ² = 7.002, P < .05; and less D10 feeding/pumping frequency a day, P < .05; and partial breastfeeding at D60, P < .05. Additionally, participants with D10 impaired secretory activation sodium-to-potassium ratio (sodium: potassium) > 0.8 were more likely to partially breastfeed at D60, P < .05.

CONCLUSION

Elevated milk sodium and sodium: potassium are biomarkers related to variables indicative of low milk supply. Therefore, immediate milk testing can be useful in identifying lactation compromise and improving breastfeeding duration. Because breastfeeding affords maternal and infant health benefits, clinicians should identify ways to measure lactation compromise in conjunction with an examination and clinical history to provide early interventions to increase breastfeeding duration and exclusivity.

Sodium and Potassium Concentrations and Somatic Cell Count of Human Milk Produced in the First Six Weeks Postpartum and Their Suitability as Biomarkers of Clinical and Subclinical Mastitis

The sodium (Na) concentration and the ratio of Na to potassium (K; Na/K) in human milk are used commonly as biomarkers of subclinical mastitis, but limited data exist on their relationship to and ability to predict clinical mastitis. Here, we assessed concentrations of Na, K, Na/K, and somatic cell count (SCC), a mammary health biomarker used in the dairy industry, in milk prospectively collected from both breasts of 41 women over the first 6 weeks postpartum. Although values differed over time postpartum, there were no differences in mean values between breasts. Nearly one-quarter (24%) of participants experienced clinical mastitis. Somatic cell counts >4.76 × 105 cells/mL were most strongly related to development of clinical mastitis in the following week (odds ratio, 7.81; 95% CI, 2.15−28.30; p = 0.002), although relationships were also observed for SCC > 4.00 × 105 cells/mL and Na concentration >12 mmol/L. Estimates of the prevalence of subclinical mastitis in women who never progressed to clinical mastitis differed by biomarker but ranged from 20 to 75%. Despite these findings, positive predictive values (PPV) of the biomarkers for identifying clinical mastitis were low (≤0.34), indicating additional research is needed to identify single biomarkers or composite measures that are highly specific, sensitive, and predictive of clinical mastitis in women.

Fatal Hypernatremic Dehydration in a Term Exclusively Breastfed Newborn

Hypernatremic dehydration in term newborns has steadily increased in incidence with increasing efforts to promote exclusive breastfeeding before hospital discharge, a key metric of the Baby-Friendly Hospital Initiative. The following report details a case of a term newborn infant who had evidence of poor intake while exclusively breastfeeding during his hospital stay that may not have been recognized by health care providers. The infant was discharged home and was subsequently found by the parents in cardiac arrest 12 h after discharge and was found to have hypernatremic dehydration. Although return of spontaneous circulation was achieved after fluid resuscitation, the infant sustained extensive hypoxic-ischemic brain injury due to cardiovascular collapse. Due to the infant’s extremely poor prognosis, life support was withdrawn at 19 days of age and the infant expired. This sentinel case demonstrates multiple pitfalls of current perceptions of normal vs. abnormal newborn feeding behavior, weight loss percentages, elimination patterns, and acceptable clinical thresholds believed to be safe for neonates. Newer data have shown that hypernatremia occurs commonly in healthy, term breastfed newborns at weight loss percentages previously deemed normal by most health professionals and hospital protocols. In-hospital strategies to prevent excessive weight loss and screening for hypernatremia in response to signs of inadequate feeding have the potential to prevent tens of thousands of readmissions for feeding complications a year, as well as hundreds of millions in health care costs.

Reliability of an Ion-Selective Electrode as a Simple Diagnostic Tool for Mastitis

BACKGROUND

Developing a simple quantitative tool for mastitis diagnosis is essential. The Ion-Selective Electrode for sodium has been reported to reliably measure sodium concentrations in human milk.

RESEARCH AIM

To determine whether an Ion-Selective Electrode measurement of sodium:potassium ratios could serve as a diagnostic tool for mastitis and, if so, to determine the diagnostic cut-off value.

METHODS

A total of 107 milk samples, including 55 from milk bank donors and 52 from participants with mastitis, were studied. The sodium:potassium ratios were determined in 33 samples (without mastitis n = 15; with mastitis n = 18) by the Ion-Selective Electrode and ion chromatography. The remaining 74 samples (donor milk n = 40; participants with mastitis n = 34) were analyzed by Ion-Selective Electrode only. Values were averaged over three measurements for each method.

RESULTS

The median postpartum months of donors and participants with mastitis were 2 and 3 months, respectively. The mean (SD) sodium:potassium ratios without and with mastitis were 0.5 (0.1) and 1.7 (1.2), respectively. A positive correlation existed between sodium:potassium ratios obtained from the two methods (r = 0.98). Area under the curve values were 0.951 (95% CI [0.904, 0.986]) for the Ion-Selective Electrode (N = 107) and 0.978 (95% CI [0.926, 1.000]) for the ion chromatography (n = 33) methods. The optimal cut-off value for the Ion-Selective Electrode method was 0.60, with 86.5% sensitivity and 92.7% specificity.

CONCLUSIONS

The Ion-Selective Electrode was sufficiently accurate for the diagnosis of mastitis. Cohort studies are needed to explore the relationship between sodium:potassium ratios and clinical outcomes.

Etonogestrel Implant in the Postpartum Period and its Impact on Biochemical Markers in Secretory Activation: A Pilot Study

BACKGROUND

Secretory activation is characterized biochemically in human milk by a fall in sodium concentration, an increase in potassium concentration, and a decreased sodium to potassium ratio. These markers can be used to identify a delay in secretory activation which can result from hormonal birth control.

RESEARCH AIM

To evaluate if the insertion of the Etonogestrel implant early in the postpartum period would delay the time to secretory activation as measured by biochemical markers.

METHODS

We conducted a prospective, longitudinal, non-randomized, observational cohort study. Women with singleton pregnancies were identified as wanting either no birth control or the Etonogestrel implant in the postpartum period. Human milk samples were collected starting at 12 hours after delivery, and then in 12-hour increments. Samples were tested for sodium and potassium levels.

RESULTS

As in the unadjusted models, there was evidence of a difference in sodium levels at two days postpartum, with the sodium level higher by 32.29 mM (95% CI [7.39, 57.20], p = .013) in the implant group than in the no birth control method group. A difference at day 2 was observed in the ratio (sodium/potassium) levels, with a higher mean ratio in the implant group by 2.49 (95% CI [0.14, 4.85], p = .039). For potassium levels, the only difference was observed at day 4, with lower values in the implant group (p = .045).

CONCLUSION

The transition from colostrum to copious milk secretion is delayed by the early insertion of the Etonogestrel device. This is evidenced by the delay in biochemical markers normally seen in secretory activation.

A mixed method inquiry of early complementary feeding of infants in the Dominican Republic

Exclusive breastfeeding (EBF) is infrequent and decreasing over time in the Dominican Republic. This study aimed to identify patterns of, and women's rationale for, early complementary feeding. Mothers of children under 12 months of age living in a low-resource peri-urban community had three opportunities to contribute: (i) responding to feeding questions embedded in a standardized questionnaire used at a well-baby clinic (n = 101), (ii) participating in focus groups (n = 31), and (iii) engaging in home-based, semi-structured individual interviews (n = 25). Quantitative questionnaire data were analyzed to identify feeding practices as a function of child age. Textual data from the individual interviews and focus groups were systematically reviewed and coded to identify key constructs through a qualitative descriptive approach. The majority (>86%) of mothers reported breastfeeding at all monthly age bands up to six months. However, EBF was rare, with more than half reporting use of other milks and other foods by the infants' second and fifth month, respectively. Overarching themes to explain early complementary feeding from the qualitative data can be broadly captured by the complementary perceptions that there are problems with relying on breastfeeding alone and that there are benefits to early complementary feeding in the early months of an infant's life. EBF was experienced as (A) insufficient, (B) not always available, (C) sometimes not safe, (D) having potentially negative effects on the mother, and (E) bringing challenges. Complementary feeding was identified as helpful in addressing each of these concerns. Although mothers typically endorsed breastmilk as the preferable and best option for infant feeding, this did not translate into EBF and was not presented as contradictory to the use and perceived benefits of early complementary feeds.

The association of maternal gestational hyperglycemia with breastfeeding duration and markers of milk production

BACKGROUND

Previous studies focusing on the association between gestational diabetes and breastfeeding duration have been inconclusive.

OBJECTIVES

We aimed to determine whether maternal gestational hyperglycemia is associated with the duration of breastfeeding and the concentrations of markers linked to breastmilk production.

METHODS

Data from the prospective, multiethnic Growing Up in Singapore Towards Healthy Outcomes study were used to assess the association of fasting plasma glucose (FPG) and 2-h postglucose challenge (2hPG) measured at 26-28 wk of gestation with duration of breastfeeding and concentrations of protein, lactose, citrate, sodium, potassium, and zinc in breastmilk 3 wk postpartum.

RESULTS

Of the 1035 participants, 5.2% and 9.5% had elevated FPG and 2hPG, respectively, consistent with a diagnosis of gestational diabetes mellitus based on International Association of Diabetes and Pregnancy Study Groups criteria. FPG ≥5.1 mmol/L was associated with a crude reduction in median breastfeeding duration of 2.3 mo. In a model adjusted for maternal prepregnancy BMI and intention to breastfeed, FPG ≥5.1 mmol/L predicted earlier termination of any breastfeeding (adjusted HR: 1.47; 95% CI: 1.04, 2.08) but not full breastfeeding (adjusted HR: 1.08; 0.76, 1.55). 2hPG ≥8.5 mmol/L was not significantly associated with the durations of any (adjusted HR: 0.86; 95% CI: 0.62, 1.19) or full (adjusted HR: 0.85; 95% CI: 0.62, 1.18) breastfeeding. Maternal FPG was significantly and positively associated with breastmilk sodium (adjusted coefficient: 1.28; 95% CI: 1.08, 1.51) and sodium-to-potassium ratio (adjusted coefficient: 1.29; 95% CI: 1.08, 1.54) but not with other measured breastmilk components.

CONCLUSIONS

Women with FPG ≥5.1 mmol/L during pregnancy breastfeed for a shorter duration. Future work involving measurement of milk production is needed to determine whether low milk production predicts breastfeeding duration among women with elevated FPG. This trial was registered at www.clinicaltrials.gov as NCT01174875.

The rates and factors of perceived insufficient milk supply: A systematic review

Perceived insufficient milk supply (PIMS) is one of the major reasons for discontinued breastfeeding. We aimed to estimate the rates and evaluate related factors of PIMS. We searched four databases for relevant articles published from January 2000 to March 2021. We then performed a meta‐analysis of the pooled data to estimate the rates and related factors of PIMS using Stata 15.0. Descriptive analyses of textual data were performed to summarise the related factors of PIMS if data could not be synthesised quantitatively. The quality of included studies was assessed using Newcastle–Ottawa scale (NOS), AHRQ checklist or Consolidated Criteria for Reporting Qualitative Research (COREQ). Overall, 27 studies were included in this review. At different periods after delivery, approximately 50% of mothers reported PIMS as the reason for stopping breastfeeding, while for breastfeeding mothers, the incidence of PIMS ranged from 10% to 25%. Breastfeeding initiation (OR 4.22, 95%CI 1.57–11.34) and breastfeeding knowledge (OR 7.10, 95%CI 2.00–25.26) were two factors influencing PIMS. Besides, PIMS had a strong negative relationship with breastfeeding self‐efficacy (r = −0.57); moderate negative association with infant suck ability (r = −0.46) and planned breastfeeding duration (r = −0.45); and a moderate positive correlation with formula supplementation (r = 0.42). Descriptive analyses revealed that infant crying was reported to be a sign of PIMS, and inadequate intake of energy/liquids was a reported cause of it. This review identified a high proportion of women reporting PIMS, particularly among those who stopped breastfeeding. Deliberate interventions were needed to improve breastfeeding for mothers at risk.

Indicators of Secretory Activation in Mothers of Preterm Very Low Birth Weight Infants

BACKGROUND

Inconsistent information exists regarding indicators of secretory activation in mothers delivering very low birth weight infants.

RESEARCH AIMS

To compare time to the onset of secretory activation using three separate indicators. A secondary aim examined the association between indicators of secretory activation and milk production.

METHODS

Indicators of secretory activation included maternal perception, volume attainment (production of ≥ 20 mL in two consecutive expression sessions) and biomarkers (sodium and lactose) obtained at volume attainment. Milk production was measured on Days 1-7 and then weekly for 6 weeks.

RESULTS

In 69 mothers of infants born ≤ 32 weeks' gestation and < 1500 g, we found no correlation in time to secretory activation between indicators. Earlier volume attainment was associated with increased milk production on Days 1-7, 14, 21, and 28 (all p < .007). Participants who exhibited both normal lactose and sodium levels produced more milk on Days 28 and 42 (p = .028 and .011), those with only normal lactose levels produced more on Day 42 (p = .026) and those with only normal sodium levels on Day 28 (p = .036). Earlier secretory activation by volume attainment was associated with increased expression frequency during Days 2-5 (all p < .014) and participants with normal biomarkers expressed more frequently during Days 2-5 (all p < .020).

CONCLUSION

Mothers of very low birth weight infants are at risk for delayed secretory activation, which may decrease their milk production. Frequent expression during the first 5 days postpartum may promote earlier secretory activation. Valid methods of determining secretory activation are necessary to develop interventions promoting earlier secretory activation.

Maternal production of milk for infants in the neonatal intensive care unit

Mother's own milk (MOM) feeding is a cost-effective strategy to reduce risks of comorbidities associated with prematurity and improve long-term health of infants hospitalized in the Neonatal Intensive Care Unit (NICU). Significant racial and socioeconomic disparities exist in MOM provision in the NICU, highlighting the importance of developing strategies to reduce these disparities. Mothers of infants in the NICU experience many health concerns which may negatively impact lactation physiology. Objective measures of lactation physiology are limited but may assist in identifying mothers at particular risk. Several strategies to assist mothers of hospitalized infants are essential, including maternal education, qualified lactation professionals, early and frequent milk expression with a hospital-grade double electric breast pump, and providing support for transitioning to direct breastfeeding prior to discharge from the NICU.

Mother's Own Milk Biomarkers Predict Coming to Volume in Pump-Dependent Mothers of Preterm Infants

OBJECTIVE

To assess serial secretory activation biomarker concentrations (sodium [Na], potassium [K], Na:K, protein, lactose, and citrate) in mother's own milk (MOM) from breast pump-dependent mothers of preterm infants to determine associations with coming to volume (CTV), defined as producing at least 500 mL/day MOM by day 14 postpartum.

STUDY DESIGN

We collected serial MOM samples and pumped MOM volume data for 14 days postpartum in mothers who delivered at <33 weeks of gestation. Regression models and the Mann-Whitney U test were used to evaluate associations.

RESULTS

Among 40 mothers, 39 (mean gestational age, 28.8 weeks; 67% overweight/obese; 59% nonwhite) had paired MOM volume and biomarker data; 33% achieved CTV between postpartum days 6 and 14. In univariate models, MOM Na on postpartum day 5 and Na:K on days 3 and 5 were associated with CTV. Mothers achieving CTV were more likely to have postpartum Na:K ≤1 on day 3 (75% vs 25%; P = .06) and ≤0.8 on day 5 (69% vs 10%; P < .01). In a multivariable regression model, day 5 Na:K (1 unit decrease in Na:K: OR, 18.7; 95% CI, 1.13-311.41; P = .049) and maternal prepregnancy body mass index (BMI) (1 unit increase in BMI: OR, 0.88; 95% CI, 0.78-0.99; P = .04) were associated with CTV between postpartum days 6 and 14.

CONCLUSIONS

Secretory activation and CTV were compromised in breast pump-dependent mothers with preterm delivery. CTV was predicted by MOM Na level and Na:K. These biomarkers have potential as objective point-of-care measures to detect potentially modifiable lactation problems in a high-risk population.

Evidence-Based Updates on the First Week of Exclusive Breastfeeding Among Infants ≥35 Weeks

The nutritional and immunologic properties of human milk, along with clear evidence of dose-dependent optimal health outcomes for both mothers and infants, provide a compelling rationale to support exclusive breastfeeding. US women increasingly intend to breastfeed exclusively for 6 months. Because establishing lactation can be challenging, exclusivity is often compromised in hopes of preventing feeding-related neonatal complications, potentially affecting the continuation and duration of breastfeeding. Risk factors for impaired lactogenesis are identifiable and common. Clinicians must be able to recognize normative patterns of exclusive breastfeeding in the first week while proactively identifying potential challenges. In this review, we provide new evidence from the past 10 years on the following topics relevant to exclusive breastfeeding: milk production and transfer, neonatal weight and output assessment, management of glucose and bilirubin, immune development and the microbiome, supplementation, and health system factors. We focus on the early days of exclusive breastfeeding in healthy newborns ≥35 weeks' gestation managed in the routine postpartum unit. With this evidence-based clinical review, we provide detailed guidance in identifying medical indications for early supplementation and can inform best practices for both birthing facilities and providers.

Delayed Lactogenesis II is Associated With Lower Sleep Efficiency and Greater Variation in Nightly Sleep Duration in the Third Trimester

BACKGROUND

Metabolic and hormonal disturbances are associated with sleep disturbances and delayed onset of lactogenesis II.

RESEARCH AIMS

The aim of this study was to measure sleep using wrist actigraphy during gestation weeks 22 and 32 to determine if sleep characteristics were associated with blood glucose, body mass index, gestational related disease, delayed onset of lactogenesis II, or work schedule.

METHODS

Demographic data were collected at study intake from primiparous women who wore a wrist actigraph during gestation weeks 22 (n = 50) and 32 (n = 44). Start and end sleep time, total nighttime sleep, sleep efficiency, wake after sleep onset, and sleep fragmentation were measured. Night to night variability was assessed with the root mean square of successive difference. Blood glucose levels, body mass index, and gestational disease data were abstracted from medical charts. Timing of lactogenesis II was determined by survey.

RESULTS

Between gestation week 22 and 32, sleep efficiency decreased and fragmentation increased (p < .05). During gestation week 32, blood glucose was negatively correlated with sleep duration, and positively related to fragmentation (p < .05). Women who experienced delayed lactogenesis II had lower sleep efficiency and greater fragmentation (p < .05), and greater night-to-night variability in sleep start and end time, efficiency, and duration during gestation week 32 (p < .05).

CONCLUSION

Women with better sleep efficiency and more stable nightly sleep time are less likely to experience delayed onset of lactogenesis II. Interventions to improve sleep may improve maternal health and breastfeeding adequacy.

Impact of Fenugreek on Milk Production in Rodent Models of Lactation Challenge

Fenugreek, a herbal remedy, has long been used as galactologue to help mothers likely to stop breastfeeding because of perceived insufficient milk production. However, few studies highlight the efficacy of fenugreek in enhancing milk production. The aims of our study were to determine whether fenugreek increased milk yield in rodent models of lactation challenge and if so, to verify the lack of adverse effects on dam and offspring metabolism. Two lactation challenges were tested: increased litter size to 12 pups in dams fed a 20% protein diet and perinatal restriction to an 8% protein diet with eight pups’ litter, with or without 1 g.kg⁻¹.day⁻¹ dietary supplementation of fenugreek, compared to control dams fed 20% protein diet with eight pups’ litters. Milk flow was measured by the deuterium oxide enrichment method, and milk composition was assessed. Lipid and glucose metabolism parameters were assessed in dam and offspring plasmas. Fenugreek increased milk production by 16% in the litter size increase challenge, resulting in an 11% increase in pup growth without deleterious effect on dam-litter metabolism. Fenugreek had no effect in the maternal protein restriction challenge. These results suggest a galactologue effect of fenugreek when mothers have no physiological difficulties in producing milk.

Contribution of Maternal Obesity to Medically Indicated and Elective Formula Supplementation in a Baby-Friendly Hospital

Objective: Determine if maternal obesity increases use of medically indicated or elective formula in the context of a Baby-Friendly Hospital with high prevalence of obesity. Study Design: We conducted a secondary analysis of mothers who initiated breastfeeding of their term, singleton infant born at a Baby-Friendly community hospital in 2016. We defined medically indicated as formula given per physician order; and elective as formula given per maternal request. We used multinomial logistic regression to determine the odds ratio (OR) and 95% confidence interval (95% CI) for medically indicated and elective formula (each versus exclusive breastfeeding) by obesity status. We adjusted for available covariates and mediating conditions that may be exacerbated by obesity. Results: A total of 1,245 mothers met inclusion criteria, of which 41% were obese. Exclusive breastfeeding, medically indicated formula, and elective formula were 84% versus 70%, 5% versus 12%, and 11% versus 18%, in nonobese versus obese women, respectively. After adjusting for covariates, obesity significantly increased the risk for medically indicated (OR 2.6 [95% CI 1.7-4.1]) and elective (OR 2.0 [95% CI 1.5-2.8]) formula. After additionally adjusting for conditions exacerbated by obesity, the risk of medically indicated formula was attenuated by 48% (OR 1.7 [95% CI 1.02-2.7]), and there was little attenuation of the risk of elective formula (OR 1.8 [95% CI 1.3-2.6]). Conclusions: In a setting with high obesity prevalence and strong support for exclusive breastfeeding, obesity accounted for 36% of medically indicated formula and 21% of elective formula use. In this era of globally increasing maternal obesity prevalence, there is an urgent need to develop successful strategies for supporting breastfeeding that goes above and beyond standard Baby-Friendly approaches.

Infant growth faltering linked to subclinical mastitis, maternal faecal-oral contamination, and breastfeeding

Infant growth faltering occurs in breastfed infants <6 months of age. The possibility that maternal health status contributes to this growth faltering is underexplored. We investigated whether (a) subclinical mastitis (SCM), an asymptomatic inflammation of the breast, (b) maternal intestinal nematode and protozoan infections, indicators of faecal-oral contamination, or (c) poor breastfeeding practices increased the odds of stunting (length-for-age z-score < -2SD), underweight (weight-for-age z-score < -2SD), or low head circumference (head circumference-for-age z-score < -2SD) in breastfed infants in rural indigenous communities in Guatemala. Mother-infant dyads (n = 105) were subdivided into those with and without SCM (milk Na:K ratio > 0.6). Maternal and infant anthropometry were measured at the time of breast milk collection. Maternal stool samples were examined for the presence of intestinal nematodes and protozoa. Questionnaires were used to characterize breastfeeding practices (exclusivity and frequency) and support, hygiene (latrine use and household faucet), and infant diarrhoea. SCM occurred in 14% of women and was associated with increased odds of infant stunting (odds ratio [OR] = 4.3; confidence interval [CI] [1.1, 15.8]), underweight (OR = 9.2; CI [1.8, 48.0]), and low head circumference (OR = 15.9; CI [2.6, 96.9]). Maternal pathogenic protozoa and nematodes were uncommon (<4%), but nonpathogenic protozoa were common (e.g., Entamoeba coli [39%]). Entamoeba coli increased the likelihood (OR = 3.3; CI [1.02, 10.6]) of low head circumference, whereas higher breastfeeding frequency lowered its odds (OR = 0.74, CI [0.56, 0.97]). Prevention of SCM may improve early infant growth, but public health measures that increase breastfeeding frequency and reduce faecal-oral contamination may be required to minimize low head circumference.

Comparison of Inductively Coupled Plasma Optical Emission Spectrometry with an Ion Selective Electrode to Determine Sodium and Potassium Levels in Human Milk

Sodium (Na), potassium (K), and the ratio Na:K in human milk (HM) may be useful biomarkers to indicate secretory activation or inflammation in the breast. Previously, these elements have been measured in a laboratory setting requiring expensive equipment and relatively large amounts of HM. The aim of this study was to compare measurements of Na and K in HM using inductively coupled plasma optical emission spectrometry (ICP-OES) with small portable ion selective electrode probes for Na and K. Sixty-five lactating women donated 5 mL samples of HM. Samples were analyzed with two ion selective probes (Na and K) and also ICP-OES. The data were analyzed using paired t-test and Bland⁻Altman plots. Na concentrations were not significantly different when measured with ion selective electrode (6.18 ± 2.47mM; range: 3.59⁻19.8) and ICP-OES (5.91 ± 3.37 mM; range: 2.59⁻21.5) (p = 0.20). K concentrations measured using the ion selective electrode (11.7 ± 2.21 mM: range: 7.69⁻18.1) and ICP-OES (11.1 ± 1.55 mM: range: 7.91⁻15.2) were significantly different (p = 0.01). However, the mean differences of 0.65 mM would not be clinically relevant when testing at point of care. Compared to ICP-OES, ion selective electrode is sufficiently accurate to detect changes in concentrations of Na and K in HM associated with secretory activation and inflammation in the mammary gland.

Correlation between Na/K ratio and electron densities in blood samples of breast cancer patients

The main purpose of this study was to investigate the relationship between the electron densities and Na/K ratio which has important role in breast cancer disease. Determinations of sodium and potassium concentrations in blood samples performed with inductive coupled plasma-atomic emission spectrometry. Electron density values of blood samples were determined via ZXCOM. Statistical analyses were performed for electron densities and Na/K ratio including Kolmogorov-Smirnov normality tests, Spearman's rank correlation test and Mann-Whitney U test. It was found that the electron densities significantly differ between control and breast cancer groups. In addition, statistically significant positive correlation was found between the electron density and Na/K ratios in breast cancer group.

Human Milk Biomarkers of Secretory Activation in Breast Pump-Dependent Mothers of Premature Infants

OBJECTIVE

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.

A genetic variant in SLC30A2 causes breast dysfunction during lactation by inducing ER stress, oxidative stress and epithelial barrier defects

SLC30A2 encodes a zinc (Zn) transporter (ZnT2) that imports Zn into vesicles in highly-specialized secretory cells. Numerous mutations and non-synonymous variants in ZnT2 have been reported in humans and in breastfeeding women; ZnT2 variants are associated with abnormally low milk Zn levels and can lead to severe infantile Zn deficiency. However, ZnT2-null mice have profound defects in mammary epithelial cell (MEC) polarity and vesicle secretion, indicating that normal ZnT2 function is critical for MEC function. Here we report that women who harbor a common ZnT2 variant (T²⁸⁸S) present with elevated levels of several oxidative and endoplasmic reticulum (ER) stress markers in their breast milk. Functional studies in vitro suggest that substitution of threonine for serine at amino acid 288 leads to hyperphosphorylation retaining ZnT2 in the ER and lysosomes, increasing ER and lysosomal Zn accumulation, ER stress, the generation of reactive oxygen species, and STAT3 activation. These changes were associated with decreased abundance of zona occludens-1 and increased tight junction permeability. This study confirms that ZnT2 is important for normal breast function in women during lactation, and suggests that women who harbor defective variants in ZnT2 may be at-risk for poor lactation performance.

Low milk supply and the pediatrician

PURPOSE OF REVIEW

Human milk is the optimal food for human infants, and provides many diverse and well described benefits for both mother and infant. Low milk supply, whether perceived or actual, is one of the most common reasons why mothers stop breastfeeding. Breastfeeding mothers often seek out the guidance and support of their pediatrician in evaluating and resolving milk production concerns.

RECENT FINDINGS

Recent evidence supports the importance of breastfeeding for maternal and child health in both developing and developed countries. Lack of knowledge regarding optimal breastfeeding management accounts for the large majority of low milk supply concerns, but there is emerging evidence that impaired glucose tolerance may contribute to intrinsic low milk supply.

SUMMARY

Breastfeeding mother-infant dyads should be followed closely until lactation is well established and the infant is gaining well. Further research is needed to understand the physiologic contributors to low milk supply and to guide evidence-based interventions to optimize maternal success in reaching breastfeeding goals, particularly for women of poorer metabolic health.