This article provides the pediatric community with a practical overview of milk expression and an update on the recent literature. Approaches for working mothers, preterm infants, critically ill infants, and mothers before lactogenesis II are presented separately, as these groups may benefit from practices tailored to individual needs.
Key points
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About 85% of breastfeeding mothers have expressed milk.
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Milk may be expressed by hand, hand-powered pumping, or electric pumping.
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For working mothers, bilateral electric pumps are often more convenient than other methods, but individual mothers may prefer alternative methods.
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For mothers of infants who cannot breastfeed directly, including preterm infants, bilateral electric breast pumps are important for developing and maintaining milk supply and may be used in conjunction with hand techniques.
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For mothers of healthy term infants who have not yet experienced lactogenesis II, hand expression may be preferable to pumping.
Milk expression
Milk expression, defined as the removal of breast milk from a mother’s breast without an infant’s mouth at her nipple, is a normal component of breastfeeding for many mothers. Survey data indicate that 85% of breastfeeding mothers express milk at some point within 4 months of delivery. Mothers practice expression for a variety of reasons, including enabling another person to feed their infant, storing milk for unexpected maternal–infant separation, relieving engorgement and/or nipple pain, maintaining milk supply, and obtaining breast milk to mix with cereal or other foods. Milk expression is more common for working mothers and for those with higher income and education.
Milk expression
Milk expression, defined as the removal of breast milk from a mother’s breast without an infant’s mouth at her nipple, is a normal component of breastfeeding for many mothers. Survey data indicate that 85% of breastfeeding mothers express milk at some point within 4 months of delivery. Mothers practice expression for a variety of reasons, including enabling another person to feed their infant, storing milk for unexpected maternal–infant separation, relieving engorgement and/or nipple pain, maintaining milk supply, and obtaining breast milk to mix with cereal or other foods. Milk expression is more common for working mothers and for those with higher income and education.
Methods of milk expression
Mothers have several options for milk expression. Review of these options also requires some clarification of the terminology used for milk expression ( Box 1 ). Hand expression may also be called manual expression and differs from hand-powered pumping, which may also be called hand pumping or manual pumping. The most commonly used form of milk expression in developed countries is electric-powered pumping. In addition, mothers may use “hands-on pumping,” which combines hand expression with electric-powered pumping. In resource-constrained areas, hand expression may be the only available approach, and may often be adequate to address maternal needs.
Hand expression
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This method is also called manual expression.
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Hand expression is when a mother uses her hands to exert pressure on her breast for milk expression.
Breast pumping
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This method uses a pump to generate a vacuum similar to that generated by the oral cavity of a feeding newborn.
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There are 2 types:
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Electrical pump: powered by battery or direct electrical current
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Hand pump: manual pumping by the mother
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Hands-on pumping
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This method combines breast compression/hand expression with simultaneous bilateral electric breast pumping.
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This method may be especially useful for mothers of premature newborns.
Hand Expression
Hand expression is an easily taught technique in which a mother uses her hand or hands to exert gentle pressure on her breast in such a way that milk is expressed. Manual hand expression with proper hygiene is no different in terms of infection risk than expression using sterile pumping equipment. Several approaches to hand expression may be used, and a mother who hand expresses regularly refines her technique until she finds the approach that is most effective for her. When teaching hand expression, a provider can suggest that the mother form a “C-shape” with her ipsilateral hand, placing her thumb 2 to 3 cm above and her fingers 2 to 3 cm below her areola. To initiate expression, the mother may press gently back toward her chest wall, exerting continuous pressure without eliciting any pain. The thumb and fingers are pressed toward the chest wall and then brought together and pressed gently forward, so that they push on the ducts beneath the areola. Milk is often expressed at this point. Using a cycle of pressing and releasing and rotating her fingers around the areola, a mother can aim to capture all the ducts until a maximum volume of milk has been expressed.
Breast Pumping
Breast pumping simulates infant suck by generating a vacuum similar to that generated by the oral cavity of a feeding newborn. Breast pumps may be bilateral or unilateral and may be powered electrically, manually, or by foot. Electric pumps are the most widely used method of expression in the United States and may be powered either by direct electrical current or by battery. Manually powered breast pumps may also be called “hand pumps,” which can be confused with hand expression.
For mothers who choose to use a pump, pumping for 15 minutes or until 2 minutes after milk flow ceases is often recommended, and this approach results in the highest volume of expressed milk, with higher fat content noted in milk removed at the end of a session of milk expression. However, studies have shown that 80% of the expressed milk is collected in the first 6 minutes, so mothers who have time constraints and are not pump dependent may wish to consider shorter durations of milk expression based on their own individual needs. A vacuum range of 0 to −250 mm Hg and 47 to 55 cycles/min may result in optimal volumes. A fundamental principle of pumping is that the level of vacuum chosen must be comfortable for the mother. Vacuum settings that are high enough to cause pain greatly increase the risk of tissue damage from pumping. One study of 21 mothers estimated that maximal comfortable vacuum is approximately −191 ± 9 mm Hg. One option is to begin a pumping session with a stimulation pattern of 1 to −250 mm Hg at 105 to 120 cycles/min, which may initiate let-down more rapidly. However, it is important for mothers to know that the initiation of let-down with a pump may be slower than with a breastfeeding infant. Let-down may occur earlier during pumping if a mother looks at a photograph of her baby or smells an item of her baby’s clothes.
Simultaneous (as opposed to sequential) pumping of both breasts is generally preferred when using electric pumps. In clinical trials, milk volumes expressed with simultaneous pumping was similar or increased compared with sequential pumping. Simultaneous pumping also takes less time, which may be of value to many mothers. Several other interventions have been shown to be effective at increasing pumped milk volume. Breast massage, warm compresses before beginning milk expression, and/or warm nipple shields may increase milk volume and decrease the time required for milk expression. In addition, recorded music-based interventions improve the volume of milk expressed by pumping.
Identifying the best type or brand of bilateral electric pump may depend more on personal preference than on an objective standard. A study comparing the Symphony breast pump (Medela, Inc, McHenry, IL, USA) with the Classic breast pump (Medela, Inc) found no differences in milk output. In another study, the Pump In Style pump (Medela, Inc) had both a higher volume of milk extracted and a higher creamatocrit compared with the Embrace pump (Playtex, Westport, CT, USA). Bernabe-Garcia and colleagues compared 4 different types of hand pumps and reported no difference between them with respect to the volume of milk expressed or the duration of milk expression. Mothers must be reminded that the volume of milk extracted by pumping may be larger or smaller than the amount extracted during an infant’s feeding. This topic is discussed later, but it is important to recognize that some mothers worry about milk supply when they notice what they perceive as a “small” volume of expressed milk, and such milk supply concern can be a major risk factor for breastfeeding discontinuation.
Considering the high prevalence of pump use, the frequency of adverse events associated with breast pumping seems to be low. The US Food and Drug Administration (FDA) received 37 reports of adverse events as a result of the use of breast pumps between 1992 and 2003, of which 24 reports identified at least 1 patient problem, including pain, soreness, discomfort, tissue damage, erythema, and swelling. Breast pumps have rarely been associated with infectious disease. In 1 reported case, contamination of breast pump equipment with Pseudomonas aeruginosa caused illness in a set of premature twins. In a separate case, a mother’s breast pump tubing changed color and was found to be colonized by Serratia marcescens . This mother discontinued breastfeeding, although neither she nor her twin infants had had signs or symptoms of illness.
Hands-on Pumping
Hands-on pumping was pioneered by Jane Morton and is an approach that combines hand expression with simultaneous bilateral electric breast pumping. This approach often produces more milk than either bilateral breast pumping or hand expression alone. This technique may be especially useful for mothers of premature newborns (see later section), who may need to generate a high level of breast milk production without direct breastfeeding. These results also highlight the importance of continued research into optimal methods of milk expression.
Comparative Effectiveness of Methods of Milk Expression
There have been several studies comparing different methods of milk expression in a variety of settings ( Table 1 ). Once a mature milk supply is well established, bilateral electric breast pumping expresses more milk in less time than unilateral pumping, hand pumping, or hand expression. Because electric pumps may remove up to 50% more milk than hand expression with greater ease, mothers who are making mature milk often strongly prefer electric pumps. However, individual mothers may prefer manual pumps or hand expression, and many mothers may be able to express adequate milk volumes using any of these approaches. In addition, although bilateral electric breast pumps have better efficacy than hand pumps and express milk more efficiently than hand pumps, these differences may not have an effect on breastfeeding duration. Hayes and colleagues examined mothers enrolled in the Women, Infants and Children (WIC) branch of the Hawaii Department of Public Health and found no difference in breastfeeding duration between working mothers who used an electric breast pump and those who used a hand pump.
| Type of Study | Author/Year | Country | Comparison Groups | Finding |
|---|---|---|---|---|
| Randomized controlled or crossover trials in mothers of premature infants or sick patients in the NICU | Fewtrell et al, 2001 | UK | Hand pump vs electric pump | Similar volumes with simultaneous electric pump/manual pump with greater volume when sequentially pumped |
| Groh-Wargo et al, 1995 | US | Simultaneous (bilateral) electric pump vs single electric pump | No difference in milk volumes. Decreased time spent for simultaneous pump | |
| Hill et al, 1999 | US | Simultaneous vs single electric pump | No difference in milk volumes | |
| Jones et al, 2001 | UK | Simultaneous vs sequential electric pumping, with or without breast massage | Simultaneous pumping resulted in greater volume compared with sequential pumping; breast massage had additive effect on both | |
| Meier et al, 2012 | US | Different electric pump suction patterns (2 groups, both simultaneous electric pumping) | A regimen with an “initiation” pattern mimicking a term infant’s rapid sucking rate and irregular sucking rhythm; when used before lactogenesis II, resulted in higher volume than a standard pattern | |
| Paul et al, 1996 | India | Manual expression vs hand pump | Hand pump resulted in greater expression | |
| Slusher et al, 2007 | Kenya and Nigeria | Electric pump, foot-operated pedal pump, and manual expression | Electric pump resulted in greater expression | |
| Crossover design for mothers of term infants (mothers who may be returning to work or school) | Auerbach, 1990 | US | Simultaneous vs single electric pump | Simultaneous pumping resulted in greater volume |
| Green et al, 1982 | US | Electric pump vs hand pump vs manual | Electric pumping resulted in greater volume than either hand pump or manual expression; the last two had similar results | |
| Observational study of mothers of premature infants | Morton et al, 2009 | US | Pre/post design of teaching “hands-on pumping” | Hands-on pumping resulted in increased milk expression volumes |
Anatomy of milk expression
The anatomy of breast pumping is different from the anatomy of hand expression. Hand expression uses positive pressure to release milk from the ducts, and with experience, may also generate let-down, which can assist in the removal of milk. A breast pump generates negative pressure, which works in 2 ways. First, the pump initiates let-down of milk an average of 4 times per pumping session. Second, the negative pressure generated in the phalange of the pump extracts milk from the ducts in a manner similar to the negative pressure generated in the posterior pharynx of the infant. The pump draws the mother’s nipple and areola deep into the phalange. Therefore, when using a pump, it is of paramount importance to choose a size for the pump shield that matches the nipple and areola of the mother. Use of a shield that is too small can cause trauma to the nipple.
Physiology of milk expression
During mature milk production, milk expression increases maternal levels of oxytocin and prolactin. Pumping has a much stronger effect on prolactin levels than does hand expression, and studies have shown that pumping increases prolactin levels even more than does direct breastfeeding. However, higher levels of prolactin and oxytocin do not necessarily correlate with increased milk production; a study comparing 2 different pumps found that one yielded a higher milk volume and a higher creamatocrit (indicating more complete breast emptying), whereas the other pump showed a much higher release in prolactin. The physiologic relationship between pumping, milk production, and hormonal regulation is clearly complex, and the current evidence base in this area often raises more questions than it answers. For example, a study found that hormonal responses to pumping are blunted among mothers with a family history of alcoholism. The hormonal response to milk expression during lactogenesis I has not been reported and might differ from the response during later phases of lactation.
Mother’s experiences of milk expression
Women’s experiences of milk expression are diverse. Some mothers find expressing milk to be a pleasant, comfortable, or relaxing activity, whereas others find milk expression painful, stressful, or embarrassing. Providers must note that their own personal experience with milk expression may not be reflective of the experience of individual mothers in their practice. In a qualitative study of milk expression experiences, one mother reported, “I feel like a cow,” whereas another said, “I like to be able to do it.” One study found that 64% of mothers who expressed breast milk had expressed in the presence of family or friends, but 36% had not. In the development of the Breast Milk Expression Experience Scale, mothers’ learning experiences related to breast milk expression ranged from 1.5 to 5 on a scale of 1 to 5, and mothers’ personal experiences ranged from 1 to 3.6 on a scale of 1 to 5. Clearly, women differ in their experience and perception of milk expression. Box 2 provides some suggested parent resources regarding milk expression.
Websites
Breastfeeding the High Risk Newborn (Lucile Packard Children’s Hospital at Stanford) http://www.lpch.org/DiseaseHealthInfo/HealthLibrary/hrnewborn/bresthub.html
Office of Women’s Health, US Department of Health and Human Services http://www.womenshealth.gov/breastfeeding/
La Leche League International http://www.lalecheleague.org/
Videos
Video of hand expression (Newborn Nursery at Lucile Packard Children’s Hospital)
The Marmet Hand Expression Technique ( about.com ) http://video.about.com/breastfeeding/Hand-Expression-Technique.htm
A Premie Needs His Mother. First Steps to Breastfeeding Your Premature Baby. Jane Morton, MD http://www.breastmilksolutions.com/premie_needs.html
Books
The Womanly Art of Breastfeeding by the La Leche League
The Breastfeeding Mother’s Guide to Making More Milk by Diana West
Nursing Mother, Working Mother , Revised Edition by Gale Pryor and Kathleen Huggins
Indications for milk expression
There are a variety of indications for milk expression, and the type and approach to milk expression may vary by indication. Return to work or school is the most common reason for regular breast pumping, and working mothers should note that the time of day affects the volume of milk extracted by pumping, with the highest volumes expressed from 6 am to noon and the lowest volumes expressed from 6 pm onward. Some mothers have no trouble expressing enough milk while working, but for those who do, it may be advisable to breastfeed the baby just before leaving for work and just after returning from work and to use a bilateral electric breast pump every 3 hours while separated from the baby. After 6 months of age, babies begin to eat solid food, maternal milk supply becomes more stable, and mothers may not need to pump as frequently or at all during separations.
Some mothers express milk as a substitute for direct breastfeeding. This situation may occur when an infant is born premature or critically ill (see later section) and may also be necessary for newborns with a cleft palate, who may not be able to generate adequate negative pressure to feed directly from their mothers’ breast. Some mothers do not want to breastfeed directly, and some have infants who have difficulty establishing an effective latch. These women may choose to feed their baby pumped milk only, but it is difficult to maintain milk supply by expression alone. Among mothers of healthy term infants who were pumping only, without direct breastfeeding, none were able to provide breast milk through 6 months. Mothers may also express milk because of casual, occasional mother–infant separation or because they want others to have the experience of feeding the baby. In some cases, mothers may express milk when they have consumed alcohol, drugs, or medication that is contraindicated with breastfeeding. In such situations, the milk must be discarded after expression.
Another common indication for milk expression is to encourage a larger milk supply. Because the use of a breast pump twice daily for 2 weeks in addition to ordinary breastfeeding increases milk production by an average of 175 mL/d for mothers who already have a good milk supply, it may be thought that milk expression has a similar effect on mothers who are experiencing milk supply challenges. For example, mothers may often initiate milk expression because of delayed onset of lactation, high newborn weight loss, or other newborn signs of inadequate milk intake. Although such milk expression after breastfeeding may often be recommended for mothers with milk supply concern, the evidence base for it is limited, with 1 randomized trial finding a trend toward lower milk transfer from mother to infant for mothers who pumped in addition to breastfeeding. Further research is needed to demonstrate the optimal approaches to milk expression for mothers having trouble establishing an adequate mature milk supply.
A globally important indication for milk expression is the use of flash pasteurization of breast milk. Much pediatric HIV infection worldwide is caused by breastfeeding, especially after complementary foods are introduced around 6 months of age. However, substituting other fluids for breast milk may result in even higher morbidity and mortality from gastroenteritis and other infectious diseases. Expressing breast milk could help reduce mother-to-infant transmission after 6 months if mothers are able to treat the expressed milk with flash pasteurization in their home kitchen. This technique has been demonstrated to be feasible and safe, with its effectiveness requiring further study.
Early milk expression
Early milk expression, before the onset of lactogenesis II, differs from milk expression occurring after the onset of lactogenesis II in several important respects and is discussed separately in this section. In the United States, about half of breastfeeding mothers express milk during the first week after birth, and almost all who express milk in this early time do so using a mechanical pump. The first few days after birth are a period of dramatic maternal hormonal changes, with rapidly increasing levels of prolactin and oxytocin initiating and maintaining lactation. The effect of milk expression on hormones during this early period is unknown, but it is possible that early expression may raise hormone levels and hasten the onset of lactogenesis II. However, it is also possible that early milk expression is not effective at hastening lactogenesis II. Milk volume is low during lactogenesis I, and at each feeding or expression, mothers produce about 0 to 5 mL of colostrum, a thick fluid rich in immunoglobulins. These small volumes are in stark contrast to the volumes produced once lactogenesis II begins, and mothers begin to make copious volumes of mature, white milk. The effect of the type of expression on the volume of milk expressed before the onset of mature milk production has not yet been determined, with some studies reporting that hand expression removes more milk than pumping and some studies reporting the opposite. One study also found that a breast pump suction pattern that mimics the rapid suck rate and irregular suck rhythm of a breastfeeding newborn before the onset of lactogenesis II did not have a significant effect on the volume of colostrum or the timing of onset of lactogenesis II but was associated with a higher milk output beginning on day 6.
A challenge associated with any method of early milk expression is that expression allows mothers to visualize the small volumes of milk. Mothers who are solely breastfeeding may not have a sense of how much milk they are producing, whereas milk expression makes mothers aware of the volume. Unfortunately, mothers who are not able to express significant volumes of milk may experience feelings of embarrassment and increased milk supply concern. This situation is especially challenging because maternal concern regarding low milk supply can become a self-fulfilling prophecy. Mothers with concerns about low milk supply may begin formula supplementation, which may lead to decreased infant breastfeeding demand and increased milk stasis, which may in turn lead to truly insufficient milk supply. In addition, it is important to remember that mothers in the immediate postpartum period may have residual pain or fatigue from childbirth and may have less comfort with exposing and manipulating their breasts than mothers who have been breastfeeding for weeks or months. Therefore, a mother’s reaction to milk expression before the onset of lactogenesis II may be unrelated to her reaction to milk expression once the onset of mature milk production has begun.
A recent Cochrane review found a “lack of data relating to how various methods and techniques of milk expression or pumping assist mothers to meet their own goals.” Indeed, the outcome studies have highly variable findings, and there is some evidence that the timing of initiating of pumping might have an influence. Pumping in the first month does not have a significant influence on breastfeeding duration. Furthermore, one study found that expressing breast milk (defined as either use of a mechanical pump or hand expression) in the first 3 weeks was associated with breastfeeding discontinuation by 3 months of age.
The method of expression taught in the immediate postpartum period may have a significant effect on breastfeeding and may even affect breastfeeding duration. A randomized controlled trial that compared breast pumping to hand expression reported that early hand expression increased breastfeeding rates at 2 months by 25% compared with early breast pumping. The positive effect of learning hand expression instead of pumping might be attributable to 2 factors: first, normal colostrum volume might appear more appropriate when expressed by hand rather than by pump, and second, mothers who hand expressed initially reported greater comfort expressing in front of others than mothers who initially pumped.
The WHO and the Academy of Breastfeeding Medicine recommend teaching milk expression to mothers before discharge from birth hospitalization. In addition, the Center for Disease Control has endorsed the WHO’s Baby Friendly Hospital Initiative, which requires teaching of milk expression to all mothers during birth hospitalization. These policies are based on research showing that frequent milk expression improves breastfeeding duration for mothers who have returned to paid employment and the idea that mothers are available during the birth hospitalization to learn milk expression. However, Chen and colleagues reported that receiving breast pump education from a physician or physician assistant was a risk factor for shorter breastfeeding duration, whereas receiving breast pump education from a class or support group was a protective factor associated with a longer breastfeeding duration. These associations could be attributable to differences in the quality of counseling received from these different sources, but the study’s results might also be attributable to the fact that breast pump teaching by a physician is a marker of learning breast pumping as an inpatient, which, as discussed earlier, may not be the best time to learn pumping.
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