25 Years of Research in Human Lactation: From Discovery to Translation.

Researchers have recently called for human lactation research to be conceptualized as a biological framework where maternal and infant factors impacting human milk, in terms of composition, volume and energy content are studied along with relationships to infant growth, development and health. This approach allows for the development of evidence-based interventions that are more likely to support breastfeeding and lactation in pursuit of global breastfeeding goals. Here we summarize the seminal findings of our research programme using a biological systems approach traversing breast anatomy, milk secretion, physiology of milk removal with respect to breastfeeding and expression, milk composition and infant intake, and infant gastric emptying, culminating in the exploration of relationships with infant growth, development of body composition, and health.

Reproducibility of the creamatocrit technique for the measurement of fat content in human milk.

Quantification of human milk (HM) fat is important for determining the energy intake of infants. The simplest and most rapid method is the creamatocrit method. However, the reliability of the creamatocrit has not been comprehensively investigated.

Causes of perception of insufficient milk supply in Western Australian mothers.

A perception of insufficient milk supply (PIMS) is associated with early discontinuation of breastfeeding. Ideally, an objective measure of milk supply would either dispel or confirm this perception and provide reassurance or guide professional advice. Clinical signs of sufficient milk intake (steady growth, sufficient elimination, infant alertness and breasts feeling full before breastfeeds and soft after breastfeeds) should provide confidence in milk supply.

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.

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.

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).

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.

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.

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).

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.

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.

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.

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.

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.

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 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.

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.

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.

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.

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.

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.

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.

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.

Why calcium in breastmilk is independent of maternal dietary calcium and vitamin D.

Adequate calcium intake is vital for infant health, and some cases of rickets have been associated with a low concentration of calcium in breastmilk. The concentration of calcium in breastmilk has been shown to vary widely both between mothers, and over the course of lactation. To address potential concerns about the adequacy of calcium intake for infants who are exclusively breastfed, we discuss the factors likely to be affecting the concentration of calcium in breastmilk.

Ultrasound imaging of infant swallowing during breast-feeding.

Coordination of infants' suck-swallow-breathing patterns is integral to safe and efficient feeding. However, assessment of these patterns is difficult and often invasive, particularly in breast-fed infants less than 4 months of age. The aims of this study were to develop an ultrasound approach to visualize swallowing in term breast-feeding infants and to determine the accuracy of ultrasound imaging of swallowing compared to respiratory inductive plethysmography (RIP).