Methods of breastmilk expression: An evidence review to inform guidelines and research priorities

Abstract

Background: Knowing which methods of breastmilk expression are effective and acceptable is important to inform clinical guidelines and enable breastfeeding of infants, particularly premature, sick and low birth weight infants. Objectives: To evaluate the best available evidence on effects and acceptability of methods of breastmilk expression and inform guidelines and research priorities. Methods: Systematic review using Cochrane methods. Electronic databases (PubMed, CINAHL, Embase, Scopus, Cochrane Central) and references of included studies were searched (July 2018). Selection criteria were RCTs comparing breastmilk expression interventions against standard care or each other, in women who had given birth to premature or term infants. Primary outcomes were quantity of milk expressed, quality of milk expressed and maternal satisfaction. Risk of bias of included studies was assessed. Main results: One Cochrane systematic review (including 41 trials) and 10 additional RCTs were included. A total of 10,134 women and their infants, most premature, were randomised in the 51 included trials, performed in a range of high-, middle-, and low-income countries. 42 RCTs contributed outcomes (data or narrative) to the review synthesis, which reported 19 comparisons. Five comparisons evaluated pump versus hand expression, seven assessed different types of pumps/pumping, four evaluated instruction/education and support, and three pumping techniques or protocols relating to timing of expression (n=3). In most trials contributing data fewer participants than the number randomised were included in the analysis, with a maximum of 1533 women included. Overall risk of bias was unclear due to lack of methodological details reported. Lack of data prohibited GRADE, subgroup and sensitivity analyses. For quantity of milk expressed, there was evidence of higher mean volume in the manual pump group compared with the hand expression group. Considering quality of milk expressed: sodium and protein concentration measures indicated a lower milk quality for women who expressed using any manual pump compared with hand expression; and sodium concentrations were lower quality for women who expressed using a large electric pump compared to hand expression. There was a higher fat content in women who expressed using any method plus breast massage compared with no breast massage. Regarding maternal satisfaction, women who used the large electric pump compared with hand expression were less satisfied (when satisfaction was compared with instruction). Women using higher vacuum pressures with their electric pump reported a higher level of confidence at discharge and at one-month post discharge. Conclusion: The evidence for effective methods of expressing is not yet clear. Further RCTs are required to inform guidelines. The full range of interventions health practitioners suggest may have positive effects on quantity and quality of milk expressed should be evaluated in future trials, which should assess a standard set of clinical outcomes, cost and maternal satisfaction, using similar measures, and at similar timepoints. Future trial should assess if/how effects vary by characteristics of mother-infant dyads, including gestational age at birth, singleton versus multiples, time since birth, mode of birth, and health status of mothers.