Additional Protein Fortification in Extremely Low Birth Weight Infants

In a retrospective, single-center study, premature infants weighing \<1250 g at birth hospitalized in investigators' neonatal intensive care unit in 2012, who were exclusively fed with fortified HM and received APF for \>12 consecutive days were included. Weight gain (g/kg•d) over the previous 7 days was calculated daily based on weight data in patients' electronic medical records. When weight gain was considered insufficient (i.e., below 20 g/kg•d) and the serum urea level was \<3 mmol/L, 1 g/kg•d protein was added. Before using the mixture, investigators verified that the osmolality was only slightly increased (from 412 to 422 mOsm/kg). Growth and digestive tolerance were compared between the week before (Wk0) and 1 and 2 weeks after (Wk1 and Wk2, respectively) the introduction of protein supplement; each participant served as his own control. Change from baseline for body weight was the main outcome. Energy and protein intake during Wk0, Wk1, and Wk2 were calculated. Standard deviation z-scores for growth parameters were calculated 7 days before, at time of protein introduction, and 7 and 14 days after . Changes in Z-scores were calculated. The digestive tolerance score and metabolic tolerance (serum urea) were assessed during Wk0, Wk1, and Wk2 (5).