Calculation of total fluid intake in 32 to 35 week gestational age infants in Canada: Does weight or day of life matter?

Abstract. Background: The daily calculation of an infant’s fluid requirements is a necessary and key component of the care of preterm infants in order to ensure physiological stability and adequate caloric and nutritional intake. However, there is little research on this practice to date. Objectives: To describe the total fluid intake (TFI) prescriptions for 32–35 completed weeks gestational age infants in a Level II nursery and neonatal intensive care unit of a single centre and to examine the impact of the different prescription practices on infant weight gain. Method: A retrospective review was conducted of TFI prescriptions on all 32–35 week gestational age infants admitted to a Level II nursery and neonatal intensive care unit. In addition, Canadian pediatricians and neonatologists were surveyed regarding their fluid management practice. Data were analyzed using descriptive statistics and a Mann-Whitney U test. Results: A total of 80.3% of infants had TFI calculated using their current weight before surpassing birthweight. Infants that had TFI calculated on their current weight after birthweight was surpassed gained a significantly greater proportion of weight by day fourteen of life than those switched before birthweight was surpassed (p < 0.001). The clinician survey indicated a wide variation in the approach to TFI prescription. Conclusion: Fluid management practice in late preterm infants is inconsistent and may lead to negative outcomes. Further investigation is warranted.

*Corresponding Author: 

Dr. Andrew Latchman, Department of Pediatrics, McMaster Children’s Hospital, 1200 Main Street West, HSC 3A33, Hamilton, ON, L8N 3Z5, Canada. Tel.: +1 905 521 2100 x75392; Fax: +1 905 524 5707; E-mail: