Prepregnancy Body Mass Index Is Associated with Time-Dependent Changes in Secretory Activation Measures During the First 7 Days Postpartum in Breast Pump-dependent Mothers of Premature Infants

Background: Little is known about the biology of secretory activation (SA) in overweight and obese (OW/OB) mothers who are breast pump dependent with a premature infant in the neonatal intensive care unit.Objective: To compare time-dependent changes in daily pumped milk volume, maternal milk sodium (Na) concentration, and Na-to-potassium (K) ratios (Na:K) in the first 14 days postpartum in breast pump-dependent mothers with prepregnancy body mass index (BMI) Design/Methods: This secondary analysis for 39 subjects, 44% (n = 17) with prepregnancy BMI <27 and 56% (n = 22) with BMI >= 27, included transformed data of outcome measures, chi-square, t-tests, and growth curve models.Results: For days 1-7, daily pumped milk volume increased significantly more rapidly for mothers with BMI <27 (65.82 mL/d) versus BMI >= 27 (33.08 mL/d), but the daily rate of change in pumped milk volume during days 8-14 was not statistically different. Daily milk Na concentration decreased significantly faster in BMI <27 (-3.93 mM/d) versus BMI >= 27 (-2.00 mM/day) during days 1-7, but was not significantly different for days 8-14. No statistical differences were noted for Na:K ratio for either time period.Conclusion: These data add biologic evidence to previous research, suggesting delayed or impaired SA in OW/OB mothers, and suggest that the window of opportunity for research and clinical interventions is days 1-7 postpartum in this population.

Automated summary

There is limited knowledge about secretory activation in overweight and obese mothers who are breast pump dependent with a premature infant in the neonatal intensive care unit. Research suggests that there is delayed or impaired SA in this population, with the window of opportunity for research and clinical interventions being the first 1-7 days postpartum.