To determine if higher of lower sodium intake in preterm infants prevents sodium imbalance and subsequent morbidity and mortality.

To determine the effects of higher versus lower sodium supplementation in preterm infants. We will undertake three comparisons.

  1. Higher (commencing ≥ 2 mmol/kg/day) versus lower (commencing < 2 mmol/kg/day) sodium supplementation in preterm infants less than 7 days of age.
  2. Higher (≥ 5 mmol/kg/day) versus lower (< 3mmol/kg/day) or intermediate (≥ 3mmol/kg/day to < 5 mmol/kg/day) sodium supplementation in preterm infants ≥ 7 days of age.
    1. Higher (≥ 5 mmol/kg/day) versus lower (< 3mmol/kg/day) sodium supplementation in preterm infants ≥ 7 days of age.
    2. Higher (≥ 5 mmol/kg/day) versus intermediate (≥ 3mmol/kg/day to < 5 mmol/kg/day) sodium supplementation in preterm infants ≥ 7 days of age.
    3. Intermediate (≥ 3mmol/kg/day to < 5 mmol/kg/day) versus lower (< 3mmol/kg/day) sodium supplementation in preterm infants ≥ 7 days of age.
  3. Early and late higher versus lower sodium intake.
    1. Higher (commencing ≥ 2 mmol/kg/day) or lower (commencing < 2 mmol/kg/day) sodium supplementation in preterm infants less than 7 days of age, and either:
      1. higher (≥ 5 mmol/kg/day) versus lower (< 3mmol/kg/day) sodium supplementation in preterm infants ≥ 7 days of age; or
      2. higher (≥ 5 mmol/kg/day) versus intermediate (≥ 3mmol/kg/day to < 5 mmol/kg/day) sodium supplementation in preterm infants ≥ 7 days of age; or
      3. intermediate (≥ 3mmol/kg/day to < 5 mmol/kg/day) versus lower (< 3mmol/kg/day) sodium supplementation in preterm infants ≥ 7 days of age.

This is a protocol.