Mother's Own Milk Biomarkers Predict Coming to Volume in Pump-dependent Mothers of Preterm Infants.

Hoban, Rebecca; Poeliniz, Clarisa Medina; Somerset, Emily; Lai, Ching Tat; Janes, Judy; Patel, Aloka L; Geddes, Donna; Meier, Paula P

OBJECTIVE To assess serial secretory activation biomarker concentrations (sodium [Na], potassium [K], Na:K ratio, protein, lactose, citrate) in mother's own milk (MOM) from pump-dependent mothers of preterm infants to determine associations with coming to volume (CTV), defined as producing at least 500mL/day MOM by day 14 postpartum. STUDY DESIGN We collected serial MOM samples and pumped MOM volume data for 14 days postpartum in mothers who delivered at <33 weeks of gestation. Regression models and Mann-Whitney tests were used to evaluate associations. RESULTS Of 40 mothers, 39 (mean gestational age 28.8 weeks; 67% overweight/obese; 59% non-white) had paired MOM volume and biomarker data; 33% achieved CTV between days 6-14 postpartum. In univariate models, MOM Na on day 5 and Na:K ratios on days 3 and 5 were associated with CTV. Mothers achieving CTV were more likely to have postpartum Na:K ratios ≤1 on day 3 (75% vs. 25%, P = .06) and ≤0.8 on day 5 (69% vs 10%, p<0.01) compared with mothers not achieving CTV. In a multivariable regression model, day 5 Na:K ratio (1 unit decrease in Na:K, OR 18.7 [95% CI 1.13-311.41], p=0.049) and maternal pre-pregnancy body mass index (BMI) (1 unit increase in BMI, OR 0.88, [95% CI 0.78-0.99], p=0.04) were associated with CTV between days 6-14. CONCLUSION Secretory activation and CTV were compromised in pump dependent mothers with preterm delivery. CTV was predicted by MOM Na and Na:K ratios. These biomarkers hold potential as objective point-of-care measures to detect potentially modifiable lactation problems in a high-risk population.