Energy, fat and nitrogen balance in healthy newborn infants during the first week after birth.

There are limited data in the literature concerning the energy, fat and nitrogen balances in healthy newborn infants of normal weight. For this reason, five healthy newborn infants were studied during the first week after birth. Balance studies on energy, fat, nitrogen, dry matter and water were performed. Oxygen consumption was determined by an open method. The weight decrease the first days was explained by a deficit of water and energy intake. Weight gain was seen when the water intake was 80-100 ml/kg/day and the energy intake 200-300 kJ/kg/day. A linear relation was found between the total evaporative water losses and ambient vapour pressure. The mean resting metabolic rate was 174 kJ/kg/day with the range 144-200 kJ/kg/day. With higher activity the metabolic rate increased 20-45%. Positive balances of nitrogen and fat were obtained when the intakes exceeded 150 and 275 mg/kg/day, respectively.