Relationships between Breastfeeding Patterns and Maternal and Infant Body Composition over the First 12 Months of Lactation.

Breastfeeding has been implicated in the establishment of infant appetite regulation, feeding patterns and body composition (BC). A holistic approach is required to elucidate relationships between infant and maternal BC and contributing factors, such as breastfeeding parameters. Associations between maternal and breastfed term infant BC (n = 20) and feeding parameters during first 12 months of lactation were investigated. BC was measured at 2, 5, 9 and/or 12 months postpartum with ultrasound skinfolds (US; infants only) and bioimpedance spectroscopy (infants and mothers). 24-h milk intake (MI) and feeding frequency (FFQ) were measured. Higher FFQ was associated with larger 24-h MI (p ≤ 0.003). Higher 24-h MI was associated with larger infant fat mass (FM) (US: p ≤ 0.002), greater percentage FM (US: p ≤ 0.008), greater FM index (FMI) (US: p ≤ 0.001) and lower fat-free mass index (FFMI) (US: p = 0.015). Lower FFQ was associated with both larger FFM (US: p ≤ 0.001) and FFMI (US: p < 0.001). Greater maternal adiposity was associated with smaller infant FFM measured with US (BMI: p < 0.010; %FM: p = 0.004; FMI: p < 0.011). Maternal BC was not associated with FFQ or 24-h MI. These results reinforce that early life is a critical window for infant programming and that breastfeeding may influence risk of later disease via modulation of BC.

Gastric emptying of different meal volumes of identical composition in preterm infants: a time series analysis.

BackgroundPreterm infants' meals typically progress to higher volumes over time. Knowledge of gastric emptying (GE) responses to differing meal volumes may inform enteral feeding management. We examined the effect of meal volume and composition on preterm GE.MethodsForty infants were studied at 33.3±1.4 (29.7-35.6) weeks postmenstrual age when fully enteral fed (target 150 ml/kg/day). Intraindividual comparisons of GE were made for paired meals of 100% and 75% prescribed volume and identical composition of mother's own milk (n=21) and pasteurized donor human milk (n=19). Serial stomach ultrasound images were used to calculate gastric residual volumes (GRVs) and remaining meal proportions (% meal).ResultsGE was faster in the early postprandial period and slowed over time (P<0.001). Reduced volume meals had slower GE rates and lower GRV (P<0.001). Serial postprandial % meal was similar between reduced and full volume meals (P=0.41). Higher milk casein concentration was associated with slower GE (P=0.04). Complete gastric emptying (GRV=0 ml) was more common in infants fed at 3 h intervals compared with those fed every 2 h (P=0.002).ConclusionEarly postprandial GE is more rapid for larger meal volumes. Stable preterm infants may tolerate feeding of a 3 h meal volume at shorter intervals.

Characterisation of sucking dynamics of breastfeeding preterm infants: a cross sectional study.

BACKGROUND: Full breastfeeding is the ultimate aim for preterm infants to ensure they receive the full benefits of human milk however, preterm infants face a number of challenges associated with their immaturity and associated morbidities. In order to facilitate oral feeding, it is essential to have a sound knowledge of the sucking dynamics of the breastfed infant. The aim of this study was to measure and describe the sucking dynamics of the preterm breastfeeding infant. METHODS: A prospective cross sectional observational study was carried out at King Edward Memorial Hospital, Perth. 38 mothers and their preterm infants (birth gestation age: 23.6-33.3 weeks; corrected gestation age 32.7 to 39.9 weeks) were recruited. Intra-oral vacuum levels, tongue movement and milk intake for a single breastfeed was measured. Statistical analysis employed linear regression and linear mixed effects models. RESULTS: Synchronised ultrasound and intra-oral vacuum measurements show that the preterm infant generates vacuum by lowering their tongue in a parallel fashion, without distortion of the nipple/nipple shield. Baseline (B), mean (M) and (P) peak suck burst vacuums weakened over the course of a feed (B: p = 0.015; M: p = 0.018; P: p = 0.044) and mean and peak vacuums were weaker if the mother fed with a nipple shield (M: p = 0.012; P: p = 0.021). Infant milk intakes were higher when infants sucked for longer (p = 0.002), sucked for a greater proportion of the feed (p = 0.002), or had a greater sucking efficiency (p < 0.001). CONCLUSIONS: Breastfeeding preterm infants generated intra-oral vacuum in the same manner as term infants. Nipple shields were associated with weaker intra-oral vacuums. However, vacuum strengths were not associated with milk intake rather time spent actively sucking was related to milk volumes. Further research is required to elucidate factors that influence preterm infant milk intake during breastfeeding.

The relationship of human milk leptin and macronutrients with gastric emptying in term breastfed infants.

BackgroundInfants breastfed on demand exhibit a variety of feeding patterns and self-regulate their nutrient intake, but factors influencing their gastric emptying (GE) are poorly understood. Despite research into appetite regulation properties of leptin, there is limited information about relationships between human milk leptin and infant GE.MethodsGastric volumes were calculated from ultrasound scans of infants' stomachs (n=20) taken before and after breastfeeding, and then every 12.5 min (median; range: 3-45 min) until the next feed. Skim milk leptin and macronutrient concentrations were measured and doses were calculated.ResultsThe leptin concentration was (mean±SD) 0.51±0.16 ng/ml; the leptin dose was 45.5±20.5 ng per feed. No relationships between both concentration and dose of leptin and time between the feeds (P=0.57; P=1, respectively) or residual stomach volumes before the subsequent feed (P=0.20; P=0.050) were found. Post-feed stomach volumes (GE rate) were not associated with leptin concentration (P=0.77) or dose (P=0.85).ConclusionGE in term breastfed infants was not associated with either skim milk leptin concentration or dose. Further investigation with inclusion of whole-milk leptin and other hormones that affect gastrointestinal activity is warranted.

Associations between Maternal Body Composition and Appetite Hormones and Macronutrients in Human Milk.

Human milk (HM) appetite hormones and macronutrients may mediate satiety in breastfed infants. This study investigated associations between maternal adiposity and concentrations of HM leptin, adiponectin, protein and lactose, and whether these concentrations and the relationship between body mass index and percentage fat mass (%FM) in a breastfeeding population change over the first year of lactation. Lactating women (n = 59) provided milk samples (n = 283) at the 2nd, 5th, 9th and/or 12th month of lactation. Concentrations of leptin, adiponectin, total protein and lactose were measured. Maternal %FM was measured using bioimpedance spectroscopy. Higher maternal %FM was associated with higher leptin concentrations in both whole (0.006 ± 0.002 ng/mL, p = 0.008) and skim HM (0.005 ± 0.002 ng/mL, p = 0.007), and protein (0.16 ± 0.07 g/L, p = 0.028) concentrations. Adiponectin and lactose concentrations were not associated with %FM (0.01 ± 0.06 ng/mL, p = 0.81; 0.08 ± 0.11 g/L, p = 0.48, respectively). Whole milk concentrations of adiponectin and leptin did not differ significantly over the first year of lactation. These findings suggest that the level of maternal adiposity during lactation may influence the early appetite programming of breastfed infants by modulating concentrations of HM components.

Determinants of body composition in breastfed infants using bioimpedance spectroscopy and ultrasound skinfolds-methods comparison.

BACKGROUND: Accurate, noninvasive, and inexpensive methods are required to measure infant body composition. Ultrasound (US) and bioimpedance spectroscopy (BIS) have been validated in adults and introduced in pediatric populations. The aim of this study was to evaluate the performance of both methods in determining percentage fat mass (%FM) in breastfed infants. METHODS: %FM of 2, 5, 9, and 12 mo-old healthy, breastfed term infants (n = 58) was calculated using BIS-derived total body water equations and skinfold equations then compared with reference models. Skinfolds were measured with US at two and four sites (biceps, suprailiac and/or triceps, and subscapular). RESULTS: %FM differed widely within and between methods, with the degree of variation affected by infant age/sex. Not a single method/equation was consistent with the distributions of appropriate reference values for all age/sex groups. Moderate number of matches with references values (13-24 out of 36) was seen for both types of equations. High number of matches (25-36) was seen for US skinfold-based equations. %FM values calculated from US and BIS were not significantly different (P = 0.35). CONCLUSION: Both BIS and US are practical for predicting %FM in infants. BIS calculations are highly dependent upon an appropriate set of validated age-matched equations.

Effect of Human Milk Appetite Hormones, Macronutrients, and Infant Characteristics on Gastric Emptying and Breastfeeding Patterns of Term Fully Breastfed Infants.

Human milk (HM) components influence infant feeding patterns and nutrient intake, yet it is unclear how they influence gastric emptying (GE), a key component of appetite regulation. This study analyzed GE of a single breastfeed, HM appetite hormones/macronutrients and demographics/anthropometrics/body composition of term fully breastfed infants (n = 41, 2 and/or 5 mo). Stomach volumes (SV) were calculated from pre-/post-feed ultrasound scans, then repeatedly until the next feed. Feed volume (FV) was measured by the test-weigh method. HM samples were analyzed for adiponectin, leptin, fat, lactose, total carbohydrate, lysozyme, and total/whey/casein protein. Linear regression/mixed effect models were used to determine associations between GE/feed variables and HM components/infant anthropometrics/adiposity. Higher FVs were associated with faster (-0.07 [-0.10, -0.03], p < 0.001) GE rate, higher post-feed SVs (0.82 [0.53, 1.12], p < 0.001), and longer GE times (0.24 [0.03, 0.46], p = 0.033). Higher whey protein concentration was associated with higher post-feed SVs (4.99 [0.84, 9.13], p = 0.023). Longer GE time was associated with higher adiponectin concentration (2.29 [0.92, 3.66], p = 0.002) and dose (0.02 [0.01, 0.03], p = 0.005), and lower casein:whey ratio (-65.89 [-107.13, -2.66], p = 0.003). FV and HM composition influence GE and breastfeeding patterns in term breastfed infants.

The Effects of Leptin on Breastfeeding Behaviour.

Breastfed infants have a reduced risk of becoming overweight and/or obese later in life. This protective effect has been partly attributed to leptin present in breastmilk. This study investigated 24-h variations of skim milk leptin and its relationship with breastmilk macronutrients and infant breastfeeding patterns. Exclusive breastfeeding mothers of term singletons (n = 19; age 10 ± 5 weeks) collected pre- and post-feed breastmilk samples for every breastfeed over a 24-h period and test-weighed their infants to determine milk intake at every breastfeed over a 24-h period. Samples (n = 454) were analysed for leptin, protein, lactose and fat content. Skim milk leptin concentration did not change with feeding (p = 0.184). However, larger feed volumes (>105 g) were associated with a decrease in post-feed leptin levels (p = 0.009). There was no relationship between the change in leptin levels and change in protein (p = 0.313) or lactose levels (p = 0.587) between pre- and post-feed milk, but there was a trend for a positive association with changes in milk fat content (p = 0.056). Leptin concentration significantly increased at night (p < 0.001) indicating a possible 24-h pattern. Leptin dose (ng) was not associated with the time between feeds (p = 0.232). Further research should include analysis of whole breastmilk and other breastmilk fractions to extend these findings.

Persistent Nipple Pain in Breastfeeding Mothers Associated with Abnormal Infant Tongue Movement.

BACKGROUND: Infants of breastfeeding mothers with persistent nipple pain have been shown to apply stronger vacuums to the breast and transfer less milk during one monitored feed. This may be associated with differences in the movement of the tongue. The aim was to analyse the intra-oral nipple shape and movement of the tongue of infants of mothers with and without nipple pain. METHODS: Breastfeeding infants of mothers with or without nipple pain were monitored using ultrasound and intra-oral vacuum during one breastfeed. From cine clips of the ultrasound scans measurements were made of the depth of the intra-oral space between the hard-soft palate junction (HSPJ) and the mid-tongue; the distance of the tip of the nipple to the HSPJ; and nipple diameters from the tip to the base. RESULTS: During nutritive sucking, tongue movements of infants of mothers with nipple pain resulted in a smaller intra-oral space (p = 0.040) and restricted nipple expansion compared to controls (p < 0.012). Stronger baseline and peak vacuums compared to controls were confirmed (p = 0.002). CONCLUSION: In these mothers, nipple pain was associated with restricted infant tongue movement. Ultrasound may complement measurement of intra-oral vacuum in monitoring treatment strategies in breastfeeding women experiencing nipple pain.

Gene expression in breastmilk cells is associated with maternal and infant characteristics.

Breastmilk is a rich source of cells with a heterogeneous composition comprising early-stage stem cells, progenitors and more differentiated cells. The gene expression profiles of these cells and their associations with characteristics of the breastfeeding mother and infant are poorly understood. This study investigated factors associated with the cellular dynamics of breastmilk and explored variations amongst women. Genes representing different breastmilk cell populations including mammary epithelial and myoepithelial cells, progenitors, and multi-lineage stem cells showed great variation in expression. Stem cell markers ESRRB and CK5, myoepithelial marker CK14, and lactocyte marker α-lactalbumin were amongst the genes most highly expressed across all samples tested. Genes exerting similar functions, such as either stem cell regulation or milk production, were found to be closely associated. Infant gestational age at delivery and changes in maternal bra cup size between pre-pregnancy and postpartum lactation were associated with expression of genes controlling stemness as well as milk synthesis. Additional correlations were found between genes and dyad characteristics, which may explain abnormalities related to low breastmilk supply or preterm birth. Our findings highlight the heterogeneity of breastmilk cell content and its changes associated with characteristics of the breastfeeding dyad that may reflect changing infant needs.

Impact of Measuring Milk Production by Test Weighing on Breastfeeding Confidence in Mothers of Term Infants.

AIM: The duration of exclusive breastfeeding is affected by maternal confidence and perception of milk supply, but objective measurement of milk supply is rarely used. Mothers of preterm infants have found measuring milk supply by in-home test weighing to be helpful to ascertain their infants' breastfeeding intake. This study aimed to determine if this technique affects breastfeeding confidence of mothers of term infants. MATERIALS AND METHODS: Participants filled in a survey of their breastfeeding confidence and perceptions of breastfeeding behavior prior to and after a 24-hour period of recording the times of feeds, amounts of each breastfeed or bottle feed (expressed breastmilk or formula), and amounts of breastmilk expressed. RESULTS: The breastfeeding confidence of at least 66% of mothers who were initially confident was maintained, and the breastfeeding confidence of at least 11% of mothers who were initially not confident was improved after objective measurement of milk supply and breastfeeding behavior. CONCLUSIONS: Measurement of actual milk supply and breastfeeding behavior provides objective information that can guide clinicians in the management of lactation. It can also help to maintain or improve breastfeeding confidence.

Human Milk MicroRNA and Total RNA Differ Depending on Milk Fractionation.

MicroRNA have been recently discovered in human milk signifying potentially important functions for both the lactating breast and the infant. Whilst human milk microRNA have started to be explored, little data exist on the evaluation of sample processing, and analysis to ensure that a full spectrum of microRNA can be obtained. Human milk comprises three main fractions: cells, skim milk, and lipids. Typically, the skim milk fraction has been measured in isolation despite evidence that the lipid fraction may contain more microRNA. This study aimed to standardize isolation of microRNA and total RNA from all three fractions of human milk to determine the most appropriate sampling and analysis procedure for future studies. Three different methods from eight commercially available kits were tested for their efficacy in extracting total RNA and microRNA from the lipid, skim, and cell fractions of human milk. Each fraction yielded different concentrations of RNA and microRNA, with the highest quantities found in the cell and lipid fractions, and the lowest in skim milk. The column-based phenol-free method was the most efficient extraction method for all three milk fractions. Two microRNAs were expressed and validated in the three milk fractions by qPCR using the three recommended extraction kits for each fraction. High expression levels were identified in the skim and lipid milk factions for these microRNAs. These results suggest that careful consideration of both the human milk sample preparation and extraction protocols should be made prior to embarking upon research in this area.

Gastric Emptying and Curding of Pasteurized Donor Human Milk and Mother's Own Milk in Preterm Infants.

We evaluated the effects of fortification and composition on gastric emptying and curding in un/fortified pairs of mother's own milk (MOM, n = 17) and pasteurized donor human milk (PDHM, n = 15) in preterm infants. Retained meal proportions (%) and curding were determined from sonography. Immediate and subsequent postprandial % were higher for PDHM (23%, P = 0.026; 15%, P = 0.006) and fortified meals (31.5%; 8.8%, both P < 0.001), whereas higher casein, whey, and lactose concentrations were associated with lower immediate postprandial % (all P < 0.006). Curding did not affect emptying. Influences of fortification, pasteurization, and differing breast milk compositions are small and unlikely implicated in preterm feeding intolerance.

Influences of breast milk composition on gastric emptying in preterm infants.

OBJECTIVES: The aim of the present study was to determine whether specific biochemical and energy concentrations influence gastric emptying of unfortified and fortified mother's own milk (MOM) in stable preterm infants, and whether gastric emptying differs between feeds of unfortified MOM and feeds fortified with S-26 or FM 85 human milk fortifier (HMF) when infants are fed the same volume under similar conditions. Influences of infant gestation, age, and weight, and feed characteristics were also explored. METHODS: Stomach volumes of 25 paired unfortified and fortified MOM feeds were monitored prefeed and postfeed delivery and at 30-minute intervals thereafter. For each feed, MOM samples were analyzed to determine concentrations of total protein, casein, whey, carbohydrate, lactose, fat, and energy. Fortified feed compositions were calculated by adding fortifier biochemical and energy concentrations to unfortified MOM concentrations. Ultrasound images were used to calculate infant stomach volumes. Statistical comparisons were made of paired stomach volume measurements. RESULTS: Higher feed concentrations of casein were associated with faster gastric emptying during feed delivery (P = 0.007). When compared with unfortified MOM, S-26 fortified feeds emptied similarly, whereas FM 85 fortified feeds emptied more slowly both during feed delivery and during the postprandial period (P = 0.002, <0.001, respectively). Gastric emptying was slower for 2-hourly feeds compared with that for 3-hourly feeds (P = 0.003) and in supine position compared with that in prone (P = 0.001). CONCLUSIONS: Breast milk composition influences gastric emptying in stable preterm infants, with feeds of higher casein concentration emptying faster during feeding than otherwise equivalent feeds, and FM 85 fortified MOM emptying more slowly than unfortified MOM.

Repeatability of gastric volume measurements and intragastric content using ultrasound in preterm infants.

OBJECTIVES: The aim of the present study was to determine whether serial gastric volumes and intragastric curding are repeatable within individual preterm infants when given sequential feeds of the same volume and composition. Infant and feeding characteristics that may influence differences in measured gastric volumes, echogenicity, and intragastric curding were also explored. METHODS: Ultrasound images were used to calculate gastric volumes and to rate echogenicity and intragastric curding for 20 infants. A total of 29 paired feeds of the same volume and composition were monitored prefeed and postfeed and at 30-minute intervals thereafter. Statistical comparisons of paired gastric volume measurements and agreement between echogenicity and curding ratings were made for each time point. Analyses of factors that influence discrepancies between volume measurements and between curding ratings were performed. RESULTS: Paired gastric volume measurements were repeatable (intraclass correlation coefficient [ICC] = 0.971, 0.938 < ICC < 0.987). Most (75%) discrepancies were <2 mL and increased over time, although volume differences were small. Overall moderate levels of consistency were observed for ratings of echogenicity (κ = 0.44), and curd presence (κ ≤ 0.65), density (κ = 0.41), and volume (κ = 0.47). Gastric emptying during feed delivery is influenced with infant positioning, fortification of breast milk, and feeding frequency. CONCLUSIONS: For preterm infants serial gastric volumes are repeatable and ratings of intragastric echogenicity and curding are moderately consistent when fed milk of the same volume and composition. Ultrasound has the potential to further explore factors that influence gastric emptying in the preterm infant.

Breastmilk cell and fat contents respond similarly to removal of breastmilk by the infant.

Large inter- and intra-individual variations exist in breastmilk composition, yet factors associated with these variations in the short-term are not well understood. In this study, the effects of breastfeeding on breastmilk cellular and biochemical content were examined. Serial breastmilk samples (∼5 mL) were collected from both breasts of breastfeeding women before and immediately after the first morning breastfeed, and then at 30-minute intervals for up to 3 hours post-feed on 2-4 mornings per participant. The infant fed from one breast only at each feed. Effects of pump versus hand expression for samples were evaluated. A consistent response pattern of breastmilk cell and fat contents to breastmilk removal was observed. Maximum fat and cell levels were obtained 30 minutes post-feed (P<0.01), with up to 8-fold increase in fat and 12-fold increase in cell content compared to the pre-feed values, and then they gradually decreased. Breastmilk cell viability and protein concentration did not change with feeding (P>0.05), although large intra-individual variability was noted for protein. Expression mode for samples did not influence breastmilk composition (P>0.05). It is concluded that breastmilk fat content, and thus breast fullness, is closely associated with breastmilk cell content. This will now form the basis for standardization of sampling protocols in lactation studies and investigation of the mechanisms of milk synthesis and cell movement into breastmilk. Moreover, these findings generate new avenues for clinical interventions exploring growth and survival benefits conferred to preterm infants by providing the highest in fat and cells milk obtained at 30 min post-expression.

Validation of ultrasound methods to monitor gastric volume changes in preterm infants.

OBJECTIVES: The aim of this study was to validate 4 sonographic methods of estimating stomach volume for the purpose of monitoring changes in gastric volume over time and to describe the echogenic characteristics of milk feeds. METHODS: Twenty-four infants were monitored during a single intragastric tube feed, with 2 ultrasound images of the entire stomach and an image of the antral cross-sectional area (ACSA) before, during, and after the feed. Raw measurements, 3 stomach volume calculations, and ACSA were tested for intra- and interrater agreement. Calculated stomach volumes and ACSA were compared with delivered feed volumes, and characteristics of stomach image echogenicity graded at each time point. RESULTS: Spheroid calculation of stomach volume was the most reliable and valid measure of stomach volume. Fortified breast milk feeds were more echogenic than unfortified breast milk feeds. Residual stomach volumes (median 2.12 mL, range 0.59-9.27 mL) were identified in 18 of 24 infants. CONCLUSIONS: Direct ultrasound stomach measurement (spheroid) will provide a useful research tool and a potential clinical tool for assessing gastric emptying and feeding intolerance in preterm infants.

Longitudinal changes in breastfeeding patterns from 1 to 6 months of lactation.

OBJECTIVE: The most common reason given for discontinuation of exclusive breastfeeding is perceived insufficient milk supply. Breastfed infants show more variation in feeding frequency than bottle-fed infants, and this may lead to a mother lacking confidence in her milk supply if the frequency of breastfeeding sessions does not match expectations based on bottle feeding. We aimed to assist clinicians in supporting breastfeeding mothers by providing evidence-based information on expected changes in breastfeeding patterns and milk intake during exclusive breastfeeding for 6 months. SUBJECTS AND METHODS: Mothers and their healthy infants who were exclusively breastfeeding (total 24-hour milk intake within the normal range) were studied during two to five 24-hour periods between 1 and 6 months of lactation. RESULTS: Between 1 and 3 months of lactation, the frequency of breastfeeding sessions decreased, whereas both the median and maximum breastmilk intakes during each breastfeeding session increased. These parameters remained constant between 3 and 6 months. The duration of each breastfeeding session decreased steadily from 1 to 6 months, but the total 24-hour milk intake remained constant. CONCLUSIONS: Breastfeeding becomes more efficient between 1 and 3 months of lactation, although milk intake remains constant. Clinicians can give mothers confidence that these changes in breastfeeding behavior do not indicate insufficient milk supply, but may be a result of the increase in the stomach capacity of the infants and are an expected outcome of a healthy, normal breastfeeding relationship.

Expression of the Pluripotency Transcription Factor OCT4 in the Normal and Aberrant Mammary Gland.

Breast cancers with lactating features, some of which are associated with pregnancy and lactation, are often poorly differentiated, lack estrogen receptor, progesterone receptor, and HER2 expression and have high mortality. Very little is known about the molecular mechanisms that drive uncontrolled cell proliferation in these tumors and confer lactating features. We have recently reported expression of OCT4 and associated embryonic stem cell self-renewal genes in the normal lactating breast and breastmilk stem cells (hBSCs). This prompted us to examine OCT4 expression in breast cancers with lactating features and compare it with that observed during normal lactation, using rare specimens of human lactating breast. In accordance with previous literature, the normal resting breast (from non-pregnant, non-lactating women) showed minimal OCT4 nuclear expression (0.9%). However, this increased in the normal lactating breast (11.4%), with further increase in lactating adenomas, lactating carcinomas, and pregnancy-associated breast cancer (30.7-48.3%). OCT4 was expressed in the epithelium and at lower levels in the stroma, and was co-localized with NANOG. Comparison of normal non-tumorigenic hBSCs with OCT4-overexpressing tumorigenic breast cell lines (OTBCs) demonstrated upregulation of OCT4, SOX2, and NANOG in both systems, but OTBCs expressed OCT4 at significantly higher levels than SOX2 and NANOG. Similar to hBSCs, OTBCs displayed multi-lineage differentiation potential, including the ability to differentiate into functional lactocytes synthesizing milk proteins both in vitro and in vivo. Based on these findings, we propose a hypothesis of normal and malignant transformation in the breast, which centers on OCT4 and its associated gene network. Although minimal expression of these embryonic genes can be seen in the breast in its resting state throughout life, a controlled program of upregulation of this gene network may be a potential regulator of the normal remodeling of the breast toward a milk-secretory organ during pregnancy and lactation. Deregulation of this gene network either within or outside pregnancy and lactation may lead to aberrant breast cell proliferation and malignant transformation, suggesting a role of these genes in both normal lactation and breast oncogenesis.

Longitudinal changes in suck-swallow-breathe, oxygen saturation, and heart rate patterns in term breastfeeding infants.

BACKGROUND: Despite the differences in breastfeeding and bottle-feeding, our understanding of how suck-swallow-breathe (SSwB), oxygenation, and heart rate patterns change as the infant ages is based predominantly on bottle-feeding studies. Therefore, this study aimed to measure how SSwB, oxygenation, and heart rate patterns changed during the first 4 months of lactation in term breastfeeding infants. METHODS: Infants less than 1 month postpartum (n = 15) were monitored early in lactation and again later in lactation (2-4 months postpartum). Simultaneous recordings of vacuum, tongue movement, respiration, swallowing, oxygen saturation, and heart rate were made during both nutritive sucking and non-nutritive sucking during breastfeeding. RESULTS: Infants transferred a similar amount of milk (P = .15) over a shorter duration later in lactation (P = .04). Compared to early lactation, suck bursts became longer (P < .001), pauses became shorter (P < .001), vacuum levels decreased (all P < .05), oxygen saturation increased (P < .001), and heart rate decreased (P < .001) later in lactation. CONCLUSION: This study confirmed that term infants become more efficient at breastfeeding as they age, primarily by extending their suck bursts and pausing less. Although infants demonstrated satisfactory SSwB coordination during early lactation, they showed a level of adaption or conditioning at later lactation by applying weaker vacuum levels and demonstrating improved cardiorespiratory responses.