Background: Breastfeeding is important for health. However, not all infants can feed at the breast and effective methods of expressing milk have not been adequately evaluated.
Objectives: To assess acceptability, effectiveness, safety, effect on milk composition, bacterial contamination of milk and cost implications of a range of methods of milk expression, including hand expression and manual, battery and electric pumps.
Search strategy: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (December 2007), CINAHL (1982 to July 2007), handsearched relevant journals and conference proceedings, scanned secondary references and contacted experts in the field.
Selection criteria: Randomised and quasi-randomised controlled trials that compared one method or technique of milk expression or pumping with other(s), at any time after birth, and cross-over trials that commenced at least 28 days after birth.
Data collection and analysis: Two authors independently assessed trial quality and extracted data. We sought additional information from the trial authors.
Main results: Twelve studies met the inclusion criteria of which six (397 mothers) provided data that could be used in the analyses. Compared with hand expression, one study found a significantly greater total volume of milk expressed over six days both with the electrical pump (373.10 ml, 95% confidence interval (CI) 161.09 to 585.11), and with the foot-operated pump (212.10 ml, 95% CI 9.39 to 414.81); however, the difference found between the foot pump and the electric pump was not significant. Mothers provided with a relaxation tape produced a greater volume of milk at one expression than women not provided with the tape (34.70 ml, 95% CI 9.51 to 59.89). Simultaneous pumping took less time than sequential pumping in one study (3.50 hours/week, 95% CI 1.39 to 5.61). No evidence of difference was found in volume with simultaneous or sequential pumping, or for milk contamination, breastfeeding at discharge, fat content of milk, serum prolactin by method of pumping. Maternal satisfaction, adverse effects on mothers and economic effects of interventions were poorly reported.
Authors' conclusions: Mothers appear to obtain greater total volumes of milk in six days after birth using the electric or foot powered pump tested compared to hand expression, and a greater volume at one expression during the second week when provided with a relaxation tape. Simultaneous pumping takes less time compared to sequential pumping. Further research with larger numbers and more comprehensive reporting is needed, and mothers' reasons for expressing linked to their evaluation of effectiveness rather than market-led research on equipment performance.