Measures of Lactation Outcomes in Women Delivering Preterm Infants

Mother's own milk (MOM) is well known to decrease prematurity-related morbidities, yet mothers delivering preterm infants often produce insufficient quantities of milk to provide these benefits. Although a critical need exists for research to support lactation success in this vulnerable population, development and investigation of interventions to increase available MOM for infant consumption requires consistent, valid, and reliable measures of lactation outcomes.

The aim of this study was to compare and contrast methods of measuring lactation outcomes in mothers of preterm infants and evaluate their advantages and disadvantages.

Measures of lactation outcomes were reviewed and synthesized. Insights on best practices and future research directions are provided.

Volume of MOM produced, lactation duration, and time to onset of secretory activation are important measures of lactation success. The most valid and reliable measure of milk production is likely weighing each vial of expressed milk combined with test weighing when infants breastfeed. Measures of lactation duration should include actual days mothers lactated rather than limiting to infant consumption of MOM as a proxy for duration and include not only whether mothers are lactating at infant discharge but whether they are also lactating at other health-relevant time points during hospitalization. Although time to onset of secretory activation is an important lactation outcome, information regarding valid and reliable indicators of onset in women delivering preterm infants is limited, and investigation of such indicators is a research priority. Variables that may affect lactation outcomes, including time to initiation of expression following delivery, duration of expression sessions, expression method, time spent in skin-to-skin care, maternal demographics and comorbidities, as well as maternal intent to lactate, must be considered when researchers investigate lactation outcomes in mothers of very low birth weight infants.

Consistent and valid measures of lactation outcomes are required to produce reliable results from which evidence-based practice recommendations can be developed in order to improve lactation success in this vulnerable population.