Pumping Behaviors of Breast Pump-Dependent Mothers of Preterm Infants in the Neonatal Intensive Care Unit (NICU): Importance of the First Five Postpartum Days

<b><i>Objective:</i></b> To determine if cumulative measures of pumping behaviors over the first 5 days postpartum predicted lactation outcomes by postpartum days 7 (achievement of secretory activation [SA] and pumped milk volume) and 14 (achievement of coming to volume [CTV ≥500 mL of pumped milk]) in breast pump-dependent mothers. <b><i>Methods:</i></b> This observational study had usable data for 29 mothers. Predictor and outcome variables were measured via Smart Pump technology (Medela, AG). Pumping behaviors were measured electronically. SA was measured using mothers' own milk (MOM) sodium (Na ≤16 Mmol). Pumped MOM volume was measured to the nearest 0.1 g. Cumulative pumping behaviors were calculated from birth to postpartum day 5. Breast pump use was standardized during two pumping sessions. <b><i>Results:</i></b> In this diverse sample (48% Black, 34% Hispanic, 18% other), each additional 1-hour spent pumping between postpartum days 1-5 increased odds of achieving SA by day 7 by 2.8 (<i>p</i> = 0.01) and translated into an additional 1,278 mL of pumped MOM volume. Each additional inter-pump interval >5 hours between birth and postpartum day 5 was associated with a decrease of 242 mL of pumped MOM volume by postpartum day 7 (<i>p</i> = NS). Achievement of CTV by day 14 was not significantly related to pumping behaviors during the first 5 days postpartum. <b><i>Conclusions:</i></b> The first 5 days postpartum are a critical window when breast pump use significantly affects achievement of SA and pumped MOM volume. The lack of effect on later CTV achievement suggests that effective breast pump use is essential to transition to the autocrine/paracrine control of lactation.