Relationship of Maternal and Neonatal Variables With Breastmilk Sodium

To determine breastmilk sodium changes in the first 72 hours after birth and to correlate maternal and neonatal variables with maternal breastmilk sodium.

We enrolled 245 mothers and their exclusively breast-fed neonates in this prospective cohort study. Singleton, inborn babies of greater than 34 weeks gestation, who were exclusively breastfed for the first 72 hours were included. Babies who required neonatal intensive care unit (NICU) admission, top up feeds or discharged before 72 hours were excluded. Study outcomes were changes in breast milk sodium in the first 72 hours and association of high maternal breast milk sodium with various maternal and neonatal variables.

Mean (SD) breastmilk sodium steadily declined over the first 72 hours [53.5 (19.2), 38.5 (19.0) and 22.2 (10.6) mmol/L at 24, 48, 72 hours, respectively]. Breastfeeding £8 times per 24 hours in the first three days was the only factor significantly associated with high breastmilk sodium (P=0.008). Maternal age, gravida, mode of delivery, significant neonatal weight loss, hypernatremia, neonatal morbidities like fever, irritability, lethargy and poor suck had no significant correlation with high breastmilk sodium.

Breastmilk sodium shows a steady decline in the first 72 hours after delivery. Feeding ≤8 times per day is associated high breastmilk sodium at 72 hours of age.