The purpose of this study is to determine if routinely recording fluid balance in sick neonates admitted to the pediatric ward is reliable and useful. The investigators' hypothesis is that it is not useful and reliable.

Fluid balance charts are commonly used, in the Netherlands, to assess patient fluid volume status. Some disadvantages of recording fluid intake and output are that it is time-consuming and complex. If it would give reliable and accurate information about the fluid volume status there would be a good reason for all this effort. In the few researches that have investigated this subject a low correlation has been found between the fluid balance and the weight changes of an adult patient. Own experience gives reasons to doubt about the reliability of the fluid balance in children, not rarely there is a discrepancy between the fluid balance and the weight measurement. We are interested in the relevance of recording fluid balance in neonates.

Inclusion Criteria:

• Sick neonates admitted to the neonatal ward

Exclusion Criteria:

• Admitted elsewhere before admission to the neonatal ward
• Indication for recording fluid balance
• Impossibility to measure the weight every day
• No consent parents

• lack of a more reliable assessment method of fluid status, for example central venous pressure or body impedance measurements
• moderate disease severity
• unequal distribution of premature infants amongst the study groups