Objective: There s currently no clear consensus on the optimal composition of maintenance intravenous therapy for newborns. 2015 National Institiute for Health and Clinical Excellence (NICE) guideline recommends the use of isotonic fluids as maintenance fluid therapy in term newborns. This study aims to compare isotonic (5% dextrose in 0.9%NaCl) and hypotonic (5% dextrose in 0.45%NaCl) parenteral fluid therapies in hospitalized term newborns with regard to changes in plasma Na (pNa) and complications related with fluid therapy. 
Design and settings: This was a retrospective cohort study performed in a tertiary university hospital NICU between January 2016 and April 2018.
Patients: Term newborns requiring parenteral fluid therapy were eligible for the study. Infants having moderate to severe dysnatremia (pNa<130 or >155 meq/L) or specific diagnoses requiring extraordinary fluids were excluded.
Main outcome measures: The primary outcome evaluated was the change in mean pNa (∆pNa meq/L/hour) at 24 hours or at the end of IV therapy (whichever was earlier). Secondary outcomes evaluated were the risk of hyponatremia, hypernatremia and adverse events attributable to fluid administration.
Results: Among the 108 included newborns, 57 received hypotonic fluid and the remaining received isotonic fluid therapy. The hypotonic group showed a greater ∆pNa compared to the isotonic group (0.480.28 vs 0.270.21 meq/ L/h, p=0.001). The risk of experiencing unsafe pNa decreases in the hypotonic group (∆pNa >0.5 meq/L/h) was higher than the isotonic group (OR:8.46; 95%CI:2.3-30.06). No significant difference was found between the two groups in terms of other outcomes.
Conclusion: Results indicated that hypotonic fluids could lead to unsafe pNa decreases in newborns and isotonic fluids can be protective against rapid sodium decline without causing hypernatremia.

COMPARISON OF ISOTONIC AND HYPOTONIC INTRAVENOUS FLUID TREATMENTS IN TERM NEWBORNS: IS IT TIME TO QUIT HYPOTONIC FLUIDS