Indicators of Secretory Activation in Mothers of Preterm Very Low Birth Weight Infants.

Background: Inconsistent information exists regarding indicators of secretory activation in mothers delivering very low birth weight infants.

Research Aims: To compare time to the onset of secretory activation using three separate indicators. A secondary aim examined the association between indicators of secretory activation and milk production.

Methods: Indicators of secretory activation included maternal perception, volume attainment (production of 20 mL in two consecutive expression sessions) and biomarkers (sodium and lactose) obtained at volume attainment. Milk production was measured on Days 1-7 and then weekly for 6 weeks.

Results: In 69 mothers of infants born ≤ 32 weeks' gestation and 1500 g, we found no correlation in time to secretory activation between indicators. Earlier volume attainment was associated with increased milk production on Days 1-7, 14, 21, and 28 (all < .007). Participants who exhibited both normal lactose and sodium levels produced more milk on Days 28 and 42 ( = .028 and .011), those with only normal lactose levels produced more on Day 42 ( = .026) and those with only normal sodium levels on Day 28 ( = .036). Earlier secretory activation by volume attainment was associated with increased expression frequency during Days 2-5 (all < .014) and participants with normal biomarkers expressed more frequently during Days 2-5 (all < .020).

Conclusion: Mothers of very low birth weight infants are at risk for delayed secretory activation, which may decrease their milk production. Frequent expression during the first 5 days postpartum may promote earlier secretory activation. Valid methods of determining secretory activation are necessary to develop interventions promoting earlier secretory activation.