摘要：A quiet revolution has been taking place in the feeding of US infants in the form of women using electric breast pumps. This revolution in milk expression may be a boon for both mothers and infants if more infants are fed human milk or if they receive human milk for a longer period. Milk expression may also be problematic for mothers, and it may be particularly problematic for infants if they are fed too much, fed milk of an inappropriate composition, or fed milk that is contaminated. As a result, the time has come to determine the prevalence of exclusive and periodic breast milk expression and the consequences of these behaviors for the health of mothers and their infants. Unbeknownst to most health professionals, a revolution is taking place in the way US infants are fed human milk. The recent development of efficient and effective double electric breast pumps has made it possible for many women to express their milk. In the 2005–2007 Infant Feeding Practices Study II (IFPS II), 85% of breastfeeding mothers of infants aged 1.5 to 4.5 months had successfully expressed milk at some time since their infant was born. 1 A high proportion of these women used a breast pump to express their milk regularly and over an extended period. 1 In addition, 5.6% of the mothers of these young infants never fed them at the breast; they fed them expressed milk exclusively. We believe that the possible benefits or harms resulting from this practice merit careful study and improved national data collection. We identify these research priorities and suggest ways to improve collection of relevant data. Women have been expressing their milk to feed their infants since at least the 1500s, 2 and they have been using breast pumps to assist them with this for almost two centuries. 3 , 4 Until recently, most pumps on the market were manual, inexpensive, and often ineffective. As a result, they were frustrating to use, and few women used them for extended periods. Recent advances in pump design and effectiveness have allowed women to extract their milk rapidly (in about 15 minutes using a double pump) and to continue to express their milk for weeks or months. 1 , 5 By necessity, infants are routinely fed expressed milk in cases of preterm birth 6 and multiple gestation. 7 Women also express milk when separated from the baby because of employment. 8 – 10 Even without barriers to directly latching their infant to the breast, women today frequently express their milk 1 and may even use breast pumps while doing other things, such as driving ( Figure 1 ). Open in a separate window FIGURE 1 Women use pumps and store milk under a variety of conditions, such as (a) while driving, (b) in unsanitary conditions, and (c) in a variety of containers. Lactating women who choose to pump differ systematically from those who do not. In the IFPS II, women who expressed their milk had more education and a higher household income than did those who did not express their milk. In addition, a higher proportion of women who expressed their milk were employed, did not participate in the federal Special Supplemental Nutrition Program for Women, Infants, and Children, and had not breastfed previously, compared with women who did not express their milk. 1 At present, the lay literature (e.g., magazine articles, Internet postings) remains a major source of information about maternal behavior related to milk expression, and some of these behaviors are of public health concern. Women choose to express their milk with a pump for a variety of reasons. In the IFPS II, the ability to have someone else feed the baby was the predominant reason given for expressing milk. 1 Milk expression has been an important strategy that women have used to combine breastfeeding with employment and use of child care. 9 As suggested in Internet postings, some women actually prefer expressing their milk to feeding their infants at the breast. 11 – 13 Qualitative research is now needed to develop a more nuanced understanding of women's reasons for expressing their milk with a pump and their strategies for managing the integration of at-the-breast feeding with extended use of improved pumps.
