Short-term rate of milk synthesis and expression interval of preterm mothers.

AIM: To determine the impact of the pumping regimes of women with preterm infants on the daily milk production, and on the short-term rate of milk synthesis during early lactation to support evidence-based recommendations for optimising milk production. METHODS: Mothers of preterm infants (n=25) recorded start time, finish time and expression volumes from every breast expression on days 10, 15-20 postpartum. RESULTS: Expressing more often than five times per day did not result in a significant increase in daily milk production. Milk volume per expression per breast increased for intervals between expressions of between 2and6 hours then reached a plateau when the interval between expression was 7 hours or longer. The short-term rate of milk synthesis decreased as the interval between expressions increased until about 7.5 hours at which point it begun to increase (p value associated with interval between expressions^2<0.001). CONCLUSION: The strong inverse association between the short-term rate of milk synthesis and the interval between expressions for intervals up to 7 hours suggest that the maximum interval between expressions should be 7 hours. Data suggest that, on average, the mothers should express at least five times a day to maximise daily milk production. Considering inter-individual variation, determination of an individual mother's maximum interval between expressions that does not compromise the short-term rate of milk synthesis will help to optimise daily milk production while minimising the demands on the mother's time.

Comparison of maternal milk ejection characteristics during pumping using infant-derived and 2-phase vacuum patterns.

Background: Milk ejection characteristics remain consistent throughout 12 months of lactation in women who expressed breastmilk with an electric breast pump. In addition these characteristics appear to remain constant when women are breastfeeding or pumping suggesting that milk ejection is a robust physiological response. It is not known whether the stimulation of an infant at the breast in the early post partum period influences milk ejection patterns or whether this is a programmed event. However, as more data become available on the mechanisms involved in infant feeding, pumping patterns mimicking the infant more closely may provide enhanced results. The objective of this study was to compare milk ejection characteristics obtained when using a novel infant-derived pumping pattern with an established 2-phase pattern. Methods: A convenience sample of ten lactating mothers, 1 to 40 weeks of lactation with normal milk production were recruited in 2015. Each participated in two pumping sessions in which either a 2-phase pattern or infant-derived pattern were randomly assigned. Milk volume and milk ejection characteristics were recorded and the percentage of available milk removed (PAMR) was calculated. Statistical analysis used linear mixed effects modeling to determine any differences between breasts and pump patterns with the consideration of individual variability as a random effect. Results: The number of milk ejections and milk ejection characteristics did not differ between patterns. Milk volumes removed were 53.6 ± 28.5 ml (PAMR 58.2 ± 28.4) for the 2-phase pattern and and 54.2 ± 26.3 ml (PAMR 52.2 ± 22.3) for the infant derived pattern. Peak milk flow rates were positively associated with the available milk (p = 0.0003) and PAMR (p = 0.0001), as was the volume of milk removed during each milk ejection (p = 0.001 and p = 0.0001). Conclusion: An experimental pumping pattern designed to resemble infant sucking characteristics did not alter milk ejection characteristics or milk removal parameters compared with an established 2-phase pattern. Theses findings provide further evidence that milk ejection is a robust physiological response.

Hourly Breast Expression to Estimate the Rate of Synthesis of Milk and Fat.

Objective measurement of the rate of synthesis of breast milk and fat in breastfeeding mothers requires test-weighing of each breastfeed and the measurement of each expression from each breast over 24 h, with the collection of milk samples before and after each breastfeed and expression. We sought an abbreviated technique for measuring these rates of synthesis. Participants completed a 24-h breastfeeding milk profile, and expressed their breasts on arrival at the research room and each hour thereafter for 3 h (4 expressions). The hourly rate of milk synthesis, as measured by the yield of milk from the fourth expression, was closely related to the hourly rate of milk synthesis calculated from the 24-h milk profile. The hourly rate of fat synthesis, calculated from the fat content of small samples of the first and last milk expressed during the fourth expression, was different from the rate of fat synthesis calculated from the fat content and volumes of all the breastfeeds and expressions during the 24-h milk profile. The study confirms the use of an abbreviated technique to measure the rate of breast milk synthesis, but is not reliable as a measure of the rate of fat synthesis for an individual.

Milk ejection patterns remain consistent during the first and second lactations.

OBJECTIVE: Milk ejection is a critical physiological process for successful lactation in humans and without it little milk can be removed. Individual milk ejection patterns have been shown to remain consistent between breasts at different lactation stages and using different vacuum patterns with an electric breast pump. Little is known about the milk ejection characteristics during the second lactation period in the same mother. The objective of this study was to examine milk ejection characteristics in the same woman over two lactations. METHODS: One mother took part in two pumping studies during consecutive lactations. One pumping study examined milk ejection characteristics during simultaneous breast expression during the first lactation. The second pumping study (second lactation) used two different pumping patterns. Three distinct milk ejections were measured during each pumping session. RESULTS: Measurements of milk flow were used to compare the duration and time taken to reach the peak of each milk ejection for two pumping sessions from each of the lactations. There were no significant differences in milk ejection characteristics between breasts, using different pumping patterns, or between lactations in this mother (P > .05). CONCLUSION: Milk ejection appears to be a physiological response that is consistent across consecutive lactations within the same mother. This suggests that milk ejection characteristics are established during or prior to the first lactation. The infant appears to have little influence on the milk ejection characteristics of the mother.

Breastmilk Production in the First 4 Weeks after Birth of Term Infants.

Breastmilk provides the ideal nutrition for the infant, and exclusive breastfeeding is recommended for the first 6 months. Adequate milk production by the mother is therefore critical, and early milk production has been shown to significantly affect milk production during established lactation. Previous studies indicate that milk production should reach the lower limit of normal for established lactation (440 mL per day) by day 11 after birth. We have used test-weighing of term infants before and after each breastfeed over 24 h to measure milk production in the first 4 weeks of lactation in mothers with and without perceived breastfeeding problems to provide information on how often milk production is inadequate. Between days 11 and 13, two-thirds of the mothers had a milk production of less than 440 mL per day, and between days 14 and 28, nearly one-third of the mothers had a milk production of less than 440 mL per day. The high frequency of inadequate milk production in early lactation and the consequence of suboptimal milk production in later lactation if left untreated suggest that objective measurement of milk production can identify mothers and infants at risk and support early intervention by a lactation specialist.

Nipple Pain in Breastfeeding Mothers: Incidence, Causes and Treatments.

BACKGROUND: Persistent nipple pain is one of the most common reasons given by mothers for ceasing exclusive breastfeeding. We aimed to determine the frequency of nipple pain as a reason for consultation, the most common attributed aetiologies, and the effectiveness of the advice and treatment given. METHODS: All consultations at the Breast Feeding Centre of Western Australia (WA) were audited over two six-month periods in 2011 (n = 469) and 2014 (n = 708). Attributed cause(s) of nipple pain, microbiology results, treatment(s) advised, and resolution of pain were recorded. RESULTS: Nipple pain was one of the reasons for consultation in 36% of cases. The most common attributed cause of nipple pain was incorrect positioning and attachment, followed by tongue tie, infection, palatal anomaly, flat or inverted nipples, mastitis, and vasospasm. Advice included correction of positioning and attachment, use of a nipple shield, resting the nipples and expressing breastmilk, frenotomy, oral antibiotics, topical treatments, and cold or warm compresses. Pain was resolving or resolved in 57% of cases after 18 days (range 2-110). CONCLUSION: The multiple attributed causes of nipple pain, possibly as a result of a cascade of events, suggests that effective early lactation management for prevention of nipple pain and early diagnosis and effective treatment are crucial to avoid early weaning.

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.

Milk ejection patterns: an intra- individual comparison of breastfeeding and pumping.

BACKGROUND: Milk ejection is a transient episode critical to milk removal and women typically have multiple milk ejections during breastfeeding and pumping. Recently it was found that milk ejection characteristics such as number of milk ejections and periodicity were consistent throughout 12 months of lactation in women who expressed their milk with an electric breast pump. It is not known whether the stimulation of an infant at the breast influences milk ejection patterns or whether this is a programmed event. The aim of this study was to compare milk ejection patterns during breastfeeding and expressing milk with an electric pump within mothers. METHODS: Twelve lactating mothers with normal milk production (502-1356 mL) had milk ejection recorded by measuring the diameter of a major milk duct with ultrasound imaging throughout an entire breastfeed and a 15-min pumping session. Scans were analysed for timing, duration of duct dilation and maximum duct diameter. RESULTS: The initial milk ejection defined as the first increase in duct diameter was observed earlier during breastfeeding than during two phase pumping sessions but was not statistically significant (p = .057). There were no significant differences between the duration of the first or second milk ejection for mothers when breastfeeding or pumping at their maximum comfortable vacuum (p = .18; p = .99). The times taken to reach the peak duct diameter, or the first half of the milk ejection were also not found to be significantly different between breastfeeding and pumping. CONCLUSION: This study suggests that milk ejection patterns remain consistent within individual mothers regardless of whether the mother is breastfeeding or expressing milk indicating a likelihood of the process either being programmed or innate to the individual.

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.

Asynchronous milk ejection in human lactating breast: case series.

BACKGROUND: Milk production is under the influence of autocrine control such that the rate of milk synthesis decreases as the breast fills with milk. Effective elimination of milk from the alveoli via the milk ejection reflex will therefore result in increased milk synthesis. It has been assumed that milk ejection occurs in all alveoli simultaneously; however, animal studies have indicated that full alveoli eject milk sooner than less full alveoli, suggesting heterogeneous emptying of the mammary gland. OBJECTIVE: The aim of this study was to determine whether milk ejection occurs asynchronously in the human lactating breast. METHODS: Retrospective analysis of videos made of ultrasound monitoring of milk ducts during pumping. Six video clips (4 women) of ultrasound monitored milk ejections showed obvious differences in the timing of milk flow between different main milk ducts. Duct diameter was simultaneously measured every second in 2 different ducts that drained 2 separate lobes of the breast. RESULTS: For 5 of 6 ultrasound duct monitoring sessions, both duct dilation and visualization of milk flow in the 2 separate main milk ducts differed by 2 to 8 seconds. For the remaining woman, milk was observed to eject from 1 part of the lobe, and when not removed, it flowed in a retrograde fashion into a different part of the lobe. CONCLUSION: Asynchrony of milk ejection occurs in the human lactating breast, suggesting that the timing of myoepithelial cell response differs, resulting in heterogeneous emptying of the gland.

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.

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.

Simultaneous breast expression in breastfeeding women is more efficacious than sequential breast expression.

INTRODUCTION: Simultaneous (SIM) breast expression saves mothers time compared with sequential (SEQ) expression, but it remains unclear whether the two methods differ in milk output efficiency and efficacy. SUBJECTS AND METHODS: The Showmilk device (Medela AG, Baar, Switzerland) was used to measure milk output and milk ejection during breast expression (electric pump) in 31 Australian breastfeeding mothers of term infants (median age, 19 weeks [interquartile range, 10-33 weeks]). The order of expression type (SIM/SEQ) and breast (left/right) was randomized. RESULTS: SIM expression yielded more milk ejections (p ≤ 0.001) and greater amounts of milk at 2, 5, and 10 minutes (p ≤ 0.01) and removed a greater total amount of milk (p ≤ 0.01) and percentage of available milk (p<0.05) than SEQ expression. After SIM expression the cream content of both the overall (8.3% [p ≤ 0.05]) and postexpression (12.6% [p ≤ 0.001]) milk were greater. During SEQ expression, the breast expressed first had a shorter time to 50% and 80% of the total amount of milk than the breast expressed second (p ≤ 0.05), but, overall, a similar percentage of available milk was removed from both breasts. CONCLUSIONS: SIM expression stimulated more milk ejections and was a more efficient and efficacious method of expression, yielding milk with a higher energy content.

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.

Blood flow characteristics of the human lactating breast.

BACKGROUND: Despite the increased metabolic activity of the lactating breast, no studies have been carried out to determine mammary blood flow (MBF) parameters or the relationship between MBF and milk production in women. The aim of this study was to measure the MBF in the internal mammary artery (IMA) and lateral thoracic artery (LTA) of lactating women and determine if these were related to milk production. METHODS: Blood flow in the IMA and LTA was measured with color Doppler ultrasound in 55 lactating women. Twenty-four-hour milk production was determined with the test-weigh method. RESULTS: IMA contributed the greater proportion of blood flow to the lactating breast (70%). MBF was highly variable between women but consistent between the left (126 L/24 h; interquartile range, 76-169) and right (110 L/24 h) breasts. No relationship between MBF and milk production was demonstrated. For 3 women, MBF was markedly reduced in 1 breast that was synthesizing almost no milk compared to the other that was producing a normal volume of milk. DISCUSSION: Although no relationship between MBF and milk production was found, the substantial reduction in blood flow in the breasts of lactating women producing almost no milk suggests a threshold below which milk production is compromised. CONCLUSION: Doppler ultrasound did not demonstrate a relationship between MBF and milk production in lactating women. Further investigation is required to fully understand the role of blood flow in milk synthesis.

Breastfeeding frequency, milk volume, and duration in mother-infant dyads with persistent nipple pain.

BACKGROUND: Nipple pain and insufficient milk supply are major causes of early weaning. We have found that persistent nipple pain was associated with strong infant sucking vacuums during breastfeeding. Several studies indicate that nipple pain and abnormal infant sucking have the potential to reduce milk transfer. We aimed to determine whether women with persistent nipple pain had low milk supply. SUBJECTS AND METHODS: The 24-hour milk production and feeding characteristics of mothers with persistent nipple pain (n=21) were compared with those mothers without nipple pain (n=21). Milk productions were measured by test-weighing the infant before and after every feed from each breast over a 24-26-hour period. Comparisons were made using Student's t tests and linear mixed models as appropriate. RESULTS: Lower milk productions were associated with longer meal durations for mothers with pain. There were no significant differences in the average 24-hour milk production or any feeding characteristics between the groups. However, four women with persistent nipple pain had milk production levels below 500 mL/day. CONCLUSIONS: The majority of breastfeeding women experiencing persistent nipple pain were able to achieve normal milk production levels. Feeding duration and frequency were similar to those of women not experiencing pain. However, longer meal durations in the pain group were associated with lower levels of milk production. Further investigation is necessary to identify mothers most affected by maternal nipple pain.

Dynamics of milk removal during simultaneous breast expression in women.

OBJECTIVE: To investigate the dynamics of milk removal during breast expression. SUBJECTS AND METHODS: This study used a continuous weighing balance to determine changes in milk flow rate and their relationship to the proportion of milk removed over time and the percentage of the available milk removed during simultaneous expression (15 minutes) of the left and right breasts in 34 mothers of healthy, term, breastfeeding infants. RESULTS: Multiple milk ejections (5.1±2.0; range, two to 14) were detected as increases in milk flow rate. A larger total expression volume was associated with a higher maximum milk flow rate (p<0.001). However, 14% less of the available milk was removed for a 100 g increase in available milk (p<0.001). After 2.9±1.4 and 6.0±2.5 minutes, 50% and 80%, respectively, of the total expression volume was removed. Milk flow was more active in the first 7 minutes than the last 7 minutes. At the eighth minute (midpoint), 54±25% of the available milk and 86±9% of the total expression volume were removed. CONCLUSIONS: The maximum milk flow rate was predictive of the total volume expressed. After the eighth minute of expression the milk flow rate was reduced. Increasing volumes of milk in the breast were associated with less complete breast emptying. These data suggest that long expression sessions are not required for mothers who are not pump dependent and that extending intervals between expressions results in less effective milk removal.

Principles for maintaining or increasing breast milk production.

Breastfeeding rates in many developed countries remain low, and maternal perception of insufficient milk production is a major contributing factor. Mothers with a perception of insufficient milk should be advised that normal breastfeeding frequencies, suckling times, and amounts are very variable. If objective assessment confirms insufficient milk production, mothers should ensure optimal milk removal frequency and thorough breast drainage. In addition, galactogogues can be prescribed. Understanding physiological principles underlying milk production will help clinicians reassure and assist mothers.

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.

Effect of warm breastshields on breast milk pumping.

The effect of using a warm breastshield on the efficiency, effectiveness, and comfort of expressing milk with an electric breast pump was assessed. The authors tested a standard breastshield at 25°C and a breastshield warmed to 39°C on 25 mothers using their maximum comfortable vacuum or -125 mm Hg. Using a warm breastshield effectively warmed the nipple and areola and, combined with maximum comfortable vacuum, decreased the time to remove 80% of the total milk yield and increased the percentage of available milk removed after 5 minutes of expression, with no change in the percentage of available milk removed after 15 minutes of expression compared with an ambient-temperature breastshield. The data confirmed that use of the mother's maximum comfortable vacuum was more efficient than a vacuum of -125 mm Hg. Using a warm breastshield with an electric breast pump was comfortable and improved the efficiency of milk removal.