Prevalence and Outcomes of Breast Milk Expressing in Women With Healthy Term Infants

A Systematic Review

Helene M Johns; Della A Forster; Lisa H Amir; Helen L McLachlan


BMC Pregnancy Childbirth. 2013;13(212) 

In This Article


A total of 22 papers identified were relevant to breast milk expression, but only seven papers reported the prevalence and/or outcomes of expressing amongst mothers of well term infants. Figure 1 provides a visual representation of the publications identified and reviewed.[21] All of the included papers were published subsequent to 1999. Many papers were descriptive rather than analytical and some were commentaries,[22–24] including calls for more research, more dialogue and clearer definitions of infant feeding practice.[20,22,25,26]

Figure 1.

Database search.

Included papers are summarised in tables, in chronological order, under the sub-headings:

  • Prevalence of breast milk expressing;

  • Methods of expressing;

  • Reasons why women express their milk;

  • Impact of expressing on breastfeeding outcomes;

  • Other implications of expressing.

Prevalence of Breast Milk Expressing

Seven papers were identified that reported on the prevalence of expressing amongst mothers of well, term infants. They came mainly from USA and Australia.[1–6,27] The papers vary in quality and design (Table 1).

Although several papers refer to an increase in the prevalence of expressing, the only data that actually documented such an increase were from Western Australia and Singapore.[2,6] The Perth Infant Feeding Study I (PIFS I), conducted in 1992–93 was followed by the Perth Infant Feeding Study II (PIFS II) ten years later.[2] Binns et al. reported the proportion of mothers who expressed breast milk (not necessarily expressing exclusively) during the first six weeks after birth, and found a 31% increase over ten years as well as a gradual decline in expressing after the first six weeks.[2] (The Singapore study reports exclusive expressing and is discussed below[6]).

In Mid-Western USA in 2002, Geraghty et al. found only sixteen percent (55/346) of women breastfed exclusively at the breast for the duration of their lactation and just seven percent (24/346) of the same group breastfed exclusively at the breast for a minimum of six months.[1] The authors concluded that expressing had become an integral part of human milk feeding.[1] Also in the USA, Labiner-Wolfe et al. analysed data from the Infant Feeding Practices Study II (IFPS II) (collected between 2005 and 2007), and found that 85% (1329/1564) of breastfeeding women had expressed breast milk, and that of these women, more than half had done so in the first week after birth.[3] An online study in Victoria, Australia found that 98% (885/903) of breastfeeding women had expressed at some time,[5] however, this was a very select group – as respondents were all members of the ABA.

A small proportion of women never breastfeed, but rather exclusively breast milk feed using expressed breast milk. Geraghty et al. reported that five percent of women exclusively expressed and fed breast milk, all of whom were mothers of premature infants.[1] Another study in the USA identified a six percent exclusive expressing rate amongst infants between 35 and 45 weeks gestation.[4] In Australia, Clemons and Amir found that four percent of women in their cross-sectional study expressed exclusively.[5] In comparison, the exclusive expressing group was higher in Singapore; increasing from nine to eighteen percent between 2000–01 and 2006–08, apparently at the expense of direct breastfeeding which decreased from 34 to 22 percent over the same time period.[6]

Methods of Expressing

A Cochrane review, which included 23 studies assessing breast milk expression methods found that there was no difference between manual and electric pumps in terms of breast milk production.[28] Most of the studies in the systematic review were excluded from this review because they did not meet inclusion criteria, mainly because they focused on premature or unwell infants. The papers discussed in this section are described in Table 2.

Given its universal accessibility, the simplest way to express milk is by hand, and evidence from a Japanese study demonstrates that this is the most effective method to use when expressing colostrum.[29] Hand expressing however, was associated with increased reports of local pain compared to electric breast pumping.[29] A randomised trial in the USA which compared hand expressing and pump use found that early hand expression appeared to improve breastfeeding rates at two months when compared with using a pump.[30]

Although hand expression may be just as effective,[28] and electric breast pumps are considerably more expensive than simple hand expression or the use of a hand operated pump, the use of electric breast pumps has become more popular over the last decade,[31] and in Perth, Australia, has increased threefold in ten years.[2] Electric breast pumps are a regular feature of postnatal wards of maternity hospitals in Washington, DC where Buckley, examining the views of lactation consultants about breast pumps, writes about the prominence of the breast pump, evidenced by the universality of its provision, in her words, "A breast pump for every room"[31] (p.16). The accessibility of electric breast pumps is demonstrated in an online study in Australia which found that 66% (556/843) of breastfeeding women had used an electric breast pump.[5] In a mail survey of 3,606 women from the IFPS II in the USA, women who undertook regular scheduled expressing were more likely to use electric breast pumps.[3]

Reasons Why Women Express Their Milk

Factors that appear to be associated with women's decisions to express their breast milk have been reported in some papers (Table 3). Women who experience difficulty establishing breastfeeding are more likely to express,[2,3,5,27] and mothers with premature or low birth weight infants, mothers who are unwell, those who have not previously breastfed are also more likely to express.[5,27]

Women with an elevated body mass index (BMI) are more likely to express their milk than to breastfeed, perhaps related to anxiety about exposing their bodies.[27,32] Obese women often have large breasts and may experience difficulty feeding discretely.[33] In addition these women may express because of physical difficulty with breastfeeding. Large breast size may impede maternal ability to see and or facilitate appropriate infant attachment and feeding.[33] Leonard et al. investigated breast milk expressing behaviours and concluded that expressing may support longer durations of breastfeeding in overweight or obese women.[32] Embarrassment about breastfeeding in public has been identified as a reason women express regardless of cultural background or body size.[5,34,35] Cultural differences may inhibit women from breastfeeding outside the home, leading to some women expressing so that they can avoid exposing their bodies in public.[3,5,34]

Other reasons women express include breastfeeding problems such as mastitis and breast engorgement;[2] nipple pain and difficulty with attachment to the breast;[5] concern about oversupply or undersupply[3,5,34,36] and allowing the baby to be fed by someone other than his/her mother.[2,3,34,37] Women express in order to return to paid work.[3,5,38] Those who are in paid employment are more likely to express their milk when there are flexible work arrangements and designated places to express.[39,40] In addition to women who are in paid employment expressing milk, women who have a high income are also more likely to do so.[3]

Impact of Expressing on Breastfeeding Outcomes

There have been contradictory reports regarding the association between expressing breast milk and the success and duration of breastfeeding (Table 4). Some studies suggest that expressing to feed (as opposed to breastfeeding solely at the breast) in the early postpartum period is associated with shorter duration of breastfeeding,[1,41] while others have found the reverse.[42,43] Binns et al. report on trends in the expression of breastmilk and conclude "The appropriate use of expressed breastmilk allows a mother to achieve six months of exclusive breastfeeding while giving her more options with regards to paid work or study and the management of breastfeeding difficulties"[2] (Page 8). Women who fed at the breast only were found by Schwartz et al. to breastfeed for longer[41] and Chapman et al. reported that expressing did not improve milk volumes or duration of breastfeeding.[44] On the other hand, Win et al. in Perth, Australia, explored the association between expressing and the duration of breastfeeding and reported that mothers who expressed were more likely to be breastfeeding at six months than those who didn't express.[45]

Studies that looked at duration of breast milk feeding have had differing outcomes. Ortiz et al. explored the duration of breast milk expression for women allocated to a lactation program which provided equipment and support for expressing. Findings indicated that these women were more likely to breast milk feed for longer than those who did not receive such support.[39] Geraghty et al. found that mothers who fed solely at the breast, particularly in the early weeks postpartum, were more likely to breast milk feed for longer than women who had combined breastfeeding with expressing.[1]

Implications for Maternal Health

Breast pain and nipple trauma have been associated with expressing;[5,29] they contribute to maternal discomfort and distress, and nipple trauma is known to be associated with the development of mastitis.[46] While Thorley identifies compromised mother/infant skin-to-skin contact and bonding as a result of expressing,[23] Johnson et al. call breast pumping liberating, giving the mother a means to " … negotiate some independence and manage the demands of breastfeeding"[34] (p. 900). These authors suggest that expressing may facilitate maternal independence, and give the mother freedom from the demands of her baby.[34]

Considering the paucity of discussion in the literature, it appears that the implications of expressing on maternal mental health warrants attention.

Other Implications of Expressing

A range of other possible outcomes of breast milk expression bear consideration and can be seen in Table 5. The additional handling involved in the expression, storage and subsequent bottle feeding of expressed milk creates additional risks for infection in the infant, as discussed and illustrated visually by Geraghty.[25] Breast milk, frozen and fed later loses vitamin content, and, like infant formula, it is at risk of contamination, as it is subject to more handling through the process of preparation.[47] Freezing, defrosting and reheating and microwaving all have the potential to compromise milk quality and safety.[48,49]

The infant fed from a bottle, regardless of the type of milk, is deprived of the benefits of self–regulation of intake associated with breastfeeding, which may increase the risk of subsequent childhood obesity.[50,51] Orofacial implications include the risk of dental caries associated with the use of a teat[52] and orthodontic problems associated with not breastfeeding.[53]