Abstract 198

Aims: To perform sequential measurements of EB. Subjects: 18 healthy infants, birthweight = 1.35 (0.21) kg, gestation = 210 (10) days; mean (SD). Methods: Energy expenditure(EE) was measured using indirect calorimetry. Energy Intake (EI) and absorption (EA) were measured using 48-hour nutrient balances on three occasions. A standard low birthweight formula was fed throughout the study. Data was analysed using ANOVa, p<0.05 was considered significant. Results: 54 balances and 30 EE determinations were performed at post-conceptual ages of 233(9), 243(7) & 337(4) d and weights of 1.77(0.26), 2.20(0.31) and 5.13(0.93) kg. Table EI, EA, EE, and energy, protein, and fat stored were different during 1 and 2 compared to 3. Calculated energy, protein and fat stored were greater than the reference fetus or infant at the same age. Conclusion: The nature and quantity of nutrient utilization/storage changes with age. Differences between the study and reference group may, in part, reflect methodological limitations but may also reflect increased storage associated with 'catch-up' growth.

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