Measures of Secretory Activation for Research and Practice: An Integrative Review

Maternal concern about inadequate milk volume commonly emerges in the first 2 weeks postpartum, a critical lactation period that includes secretory activation. This review summarizes the biology of secretory activation and evaluates the accuracy and feasibility of published measures of secretory activation. A systematic search of measures of secretory activation for mothers of healthy term and preterm infants yielded 62 abstracts. Following additional screening, 15 publications qualified for quantitative synthesis review and were evaluated with respect to accuracy (validated with another measure of secretory activation in the same mother) and feasibility (accessibility, cost, and ease of use). Maternal perception of milk coming in (MP) is the most feasible measure, but its accuracy has not been established. Patterns of increase in maternal milk volume have been validated with maternal milk-borne biomarkers in breastfeeding, and breast pump-dependent mothers and normal values have been published. Accuracy of serial maternal urinary lactose concentrations has not been established for secretory activation and lacks feasibility. Maternal milk biomarkers are the accurate standard to which other measures are compared but currently lack feasibility for routine use. Use of secretory activation measures can personalize lactation care by matching maternal risk with appropriate diagnostics. Priorities for research and practice include validation of MP as a population-based screening tool, implementation of techniques that measure patterns of increase in milk volume for moderate risk populations, and the development of milk biomarker science for point-of-care use in the most complicated lactation scenarios.