Considering the physiological changes in fluid and electrolyte balance and providing proper support are one of the important aspects of neonatal intensive care. Maintenance intravenous fluids are designed to maintain homeostasis when a patient is unable to uptake required water, electrolytes, and energy. Hypotonic fluids are still the most commonly prescribed IV fluids for pediatric hospitalized patients. However, previous studies, including children older than one month of age revealed that traditionally used hypotonic fluids may lead to hyponatremia.

Because of the absence of evidence-based data, there is currently no clear consensus on the optimal composition of maintenance intravenous fluid therapy in newborns, leading to wide practice variation.

The National Clinical Guideline Center (NICE) 2015 recommends the use of isotonic fluids in term newborn infants and some newborn centers has begun to use isotonic fluids since guidelines recommendations. Since the publication of the NICE guideline, no studies have addressed this topic.

In this prospective, observational , multicentric study, conventional hypotonic fluids containing sodium chloride (NaCl) < 130 mmol/L compared with isotonic fluids (containing NaCl between 131-154 mmol/L) in terms of the risk of hyponatremia, hypernatremia, plasma sodium (pNa) level change, treatment morbidities, hospitalization duration and mortality.

Inclusion Criteria are:

• Term newborns (>37 + 0/7 weeks) aged 24 hours to 30 days with a normal baseline serum sodium level between 135-145 mmol/L,with a treatment plan to include IV fluids at > 50% of maintenance
• Infants not received parenteral fluids in the last 24 hours before participation
• Infants receiving IV fluid administration at 50% to 100% of maintenance

Exclusion Criteria:

• Newborns with diagnoses that required specific fluid tonicity and volumes such as:

  • Severe dehydration presenting with shock
  • Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
  • Renal insufficiency
  • Adrenal insufficiency
  • Diabetes mellitus and diabetes insipidus
  • Hypoxic ischemic encephalopathy
  • Major congenital anomaly
  • Patients receiving diuretic therapy
  • Patients with obvious edema
  • Heart or liver failure, portal hypertension with acid
  • Pre-post operative patients
  • Infants receiving total parenteral nutritional therapy
  • Other: all conditions that require non-standard liquid content and quantities

Hospitalized term newborns (>37 weeks) , requiring iv fluid treatment after 24 hour postnatal age