Anna R. Hepworth

Oxygen Saturation and Suck-Swallow-Breathe Coordination of Term Infants during Breastfeeding and Feeding from a Teat Releasing Milk Only with Vacuum

Background. Vacuum is an important factor in milk removal from the breast, yet compression is the predominant component of milk removal from bottle teats. Since bottle-feeding infants have lower oxygen saturation, vacuum levels, and different suck-swallow-breathe (SSwB) coordination to breastfeeding infants, we hypothesised that when infants fed from a teat that required a vacuum threshold of −29 mmHg for milk removal, that oxygen saturation, heart rate, and suck-swallow-breathe (SSwB) patterns would be similar to those of breastfeeding. Study Design. Infants (n = 16) were monitored during one breastfeed and one feed from the experimental teat. Simultaneous recordings were made of oxygen saturation, heart rate, vacuum, tongue movement, respiration, and swallowing. Results. There were no differences in oxygen saturation and heart rate between the breast and the teat. Infants displayed fewer sucks and breaths per swallow during nutritive sucking (NS) compared to non-nutritive sucking (NNS). The number of sucks per breath was similar for NS and NNS although respiratory rates were slower during NS. These patterns did not differ between the breast and the teat. Conclusion. These results suggest that vacuum may be conducive to safe and coordinated milk removal by the infant during both breast and bottle-feeding.

Evaluation of a mid-infrared analyzer for the determination of the macronutrient composition of human milk.

A mid-infrared human milk analyzer (HMA) is designed to measure the macronutrients in human milk over a wide range of concentrations. Human milk samples (N = 30, 4 different dilutions each) were used to compare the macronutrient levels determined by the HMA to those derived from traditional laboratory methods. There was a small but statistically significant difference in the levels of fat, protein, lactose, total solids, and energy for all samples. These differences were consistent with subtle differences in the chemical principles governing the assays. For higher macronutrient levels, a trend to greater differences between the HMA and the laboratory method was seen, particularly in samples with high fat concentration. The intra-assay variation for the HMA for all macronutrients was less than 4%. It is concluded that that with appropriate sample preparation, the mid-infrared HMA can provide a practical measurement of macronutrients in human milk. J Hum Lact. 26(4):376-383.

Maternal and infant infections stimulate a rapid leukocyte response in breastmilk

Breastmilk protects infants against infections; however, specific responses of breastmilk immune factors to different infections of either the mother or the infant are not well understood. Here, we examined the baseline range of breastmilk leukocytes and immunomodulatory biomolecules in healthy mother/infant dyads and how they are influenced by infections of the dyad. Consistent with a greater immunological need in the early postpartum period, colostrum contained considerable numbers of leukocytes (13–70% out of total cells) and high levels of immunoglobulins and lactoferrin. Within the first 1–2 weeks postpartum, leukocyte numbers decreased significantly to a low baseline level in mature breastmilk (0–2%) (P<0.001). This baseline level was maintained throughout lactation unless the mother and/or her infant became infected, when leukocyte numbers significantly increased up to 94% leukocytes out of total cells (P<0.001). Upon recovery from the infection, baseline values were restored. The strong leukocyte response to infection was accompanied by a more variable humoral immune response. Exclusive breastfeeding was associated with a greater baseline level of leukocytes in mature breastmilk. Collectively, our results suggest a strong association between the health status of the mother/infant dyad and breastmilk leukocyte levels. This could be used as a diagnostic tool for assessment of the health status of the lactating breast as well as the breastfeeding mother and infant.

Variation in fat, lactose, and protein composition in breast milk over 24 hours associations with infant feeding patterns

Background: Data regarding the association between breast milk composition and infant feeding patterns (frequency and amount of breast milk taken) would help in understanding the regulation of food intake in breastfed infants. Objective: This study examined the relationship between breast milk macronutrient concentration and patterns of milk intake in breastfeeding infants over a 24-hour breastfeeding period. Methods: Mothers of healthy term infants (n = 15) collected pre- and postfeed breast milk samples from each feed at each breast over a 24-hour period. Breast milk samples were analyzed for fat, lactose, total protein, casein, and whey protein content. The energy content for each feed was calculated. Results: Breastfeeding patterns and milk composition varied greatly between individuals. The fat content of milk significantly differed over 24 hours (P = .01), whereas the concentration of lactose and protein content remained the same. The mean 24-hour total protein, whey, and casein intake was inversely (P < .01), whereas lactose concentration was positively (P = .03) related to the number of breast feeds per day. No relationship was seen either between fat or energy content and feeding patterns. The mean (SD) concentration of fat, lactose, and total protein over the 24-hour period was 43 (12) g/L, 68 (7) g/L, and 13 (2) g/L, respectively. Conclusion: The association between milk protein intake and the breastfeeding frequency suggests that the protein intake may play a role in infant appetite control.

Tongue movement and intra-oral vacuum of term infants during breastfeeding and feeding from an experimental teat that released milk under vacuum only

BACKGROUND Recent literature supports the theory that vacuum is integral to the removal of milk from the breast rather than peristaltic compression of the breast. AIM We aimed to determine if breastfed infants could remove breast milk from an experimental teat designed to release milk only when a vacuum is applied. METHODS Submental ultrasound images and intra-oral vacuum measurements were recorded simultaneously during both a breastfeed and a feed with the experimental teat. RESULTS Infants placed the nipple and teat a similar distance from the nipple hard-soft palate junction when the tongue was lowered (4.7 mm vs 5.3 mm). As the tongue lowered the nipple and teat expanded evenly although the nipple expanded more than the teat (3.1mm vs 1.5 mm). Both baseline (-31 mm Hg vs -12 mm Hg) and peak vacuum (-122 mm Hg vs -67 mm Hg) applied to the breast were significantly higher than for the teat. CONCLUSION Breastfed infants are able to remove milk from a teat using only vacuum with a similar tongue movement to that of breastfeeding. This evidence supports the theory that vacuum is a critical factor in the removal of milk from the breast.

Ultrasound Imaging of Infant Sucking Dynamics during the Establishment of Lactation

Background: Infant sucking problems are frequently implicated in early weaning during breastfeeding, yet our understanding of early sucking dynamics is limited. Objective: This study aimed to describe infant sucking patterns during breastfeeding at secretory activation and determine whether they changed by the time of established lactation. Methods: Sucking patterns and milk intake of 15 breastfeeding infants were assessed on day 3.2 ± 0.8 and later at follow-up, 16.0 (11.3-22.8) days postpartum. Nipple diameters, tongue movement, nipple position, and suck rate during nutritive sucking (NS) and non-nutritive sucking (NNS) were measured from ultrasound scans of the intra-oral cavity during breastfeeding. Milk intake and LATCH scores were also recorded. Results: As the tongue lowered during a suck cycle, the nipple increased in size (P < .001), milk flowed into the intra-oral space and the nipple moved closer to the hard-soft palate junction (P < .001). During NS, nipple diameters and the mid-tongue movement were greater than during NNS (P < .001). As the infant aged, the mid-tongue lowered further (P = .002), suck rates became faster (P < .001) and milk intake increased (P = .004), however, no differences were seen for LATCH scores (P = .34). Conclusion: Differences in tongue movement between NS and NNS suggest that there is an altered sucking action when milk flow is absent. Similar sucking patterns at day 3 and during established lactation imply that infants have a mature sucking pattern in the early postpartum period.

Validation of Nipple Diameter and Tongue Movement Measurements with B-Mode Ultrasound During Breastfeeding

Infant feeding problems are extremely common during breastfeeding establishment. To objectively assess infant sucking, consistent methods to analyze ultrasound images of the infants oral cavity are required. We developed and assessed the reliability of an extensive ultrasound measurement protocol by measuring nipple diameter and placement. Midline submental ultrasound scans of 30 term breastfed infants were analyzed by two raters. Nipple diameter, nipple hard-soft palate junction distance and tongue hard-soft palate junction distance were measured on two frames: tongue-up and tongue-down. No evidence of measurement bias was found between raters and inter-rater agreement and consistency scores were high. The changes in nipple diameter and placement were consistent with previous descriptions; however, the diameter of the nipple was not consistent in either position. This method provides objective measurements representative of tongue movement, and further investigation is required to ensure usefulness when examining sucking difficulties.

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.

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.

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.