OBJECTIVETo study the relationship of protein intake and energy supply with the physical growth in very/extremely low birth weight infant at their early life.

METHODRetrospective survey was performed in Neonatal Intensive Care Unit (NICU) in Peking University First Hospital. Inclusion criteria were preterm infant, birth weight < 1500 g, hospitalization for longer than 2 weeks, discharge with body weight greater than 1800 g. The infants were divided into two groups according to gestational age (GA). GA < 32 weeks and ≥ 32 weeks. Physical growth and its relation with the protein intake and energy supply were analyzed. The predictive value of serum blood urea nitrogen (BUN) on protein intake was studied.

RESULTNinety-three very/extremely low birth weight infants were involved, 69 in GA < 32 weeks group and 24 in GA ≥ 32 weeks group.Compared with GA ≥ 32 group, GA < 32 weeks preterm infants had more weight loss, (9.2 ± 4.4)% vs. (5.0 ± 3.1)%, P = 0.000; slower birth weight recovery (10.6 ± 3.8) d vs. (7.1 ± 2.6) d, P = 0.000; poorer weight gain at 1, 4, 5 weeks of life, (-4.5 ± 9.3) g/ (kg·d) vs. (3.4 ± 6.9) g/ (kg·d), P = 0.000 , (13.5 ± 7.3) g/ (kg·d) vs. (19.2 ± 4.9) g/ (kg·d), P = 0.001, (14.6 ± 5.6) g/ (kg·d) vs. (18.2 ± 4.5) g/ (kg·d), P = 0.031; less energy supply at 1 to 5 weeks (P value was 0.000,0.000,0.025,0.001,0.008 respectively) and less protein intake at 1, 4, 5 weeks of life (P value was 0.009,0.006,0.032). Extrauterine growth retardation (EUGR) was still predominant in our subjects, 47.8% in GA < 32 weeks group, and 95.8% in GA ≥ 32 weeks group, P = 0.000. The incidence increased greater in GA < 32 weeks infants, 43.5% vs. 20.8%, P = 0.000.The duration of weight loss and mechanical ventilation correlated negatively with weight gain rate, respectively β = -0.591, P = 0.000 and β = -0.281, P = 0.005; the average energy supply and time taken to reach full enteral feeding were factors improving weight gain, respectively β = 0.202, P = 0.021 and β = 0.354, P = 0.000. After birth, serum BUN declined gradually. Positive relation showed between average protein intake at 3(rd) week and BUN level at the end of 3 weeks, r = 0.420, P = 0.000. Serum BUN 1.44, 1.49 mmol/L at the end of 3(rd) and 4(th) week were cut-off predictors for protein intake less than 3 g/(kg·d) at related period, sensitivity and specificity were 65.3%, 83.3% and 60%, 80% respectively.

CONCLUSIONNo enough protein intake and energy supply, poor weight gain are critical problems in the management of very/extremely low birth weight infants. Prevention from NEC, appropriate parenteral/enteral nutrition transforming will benefit their physical growth. Low serum BUN after 3 weeks of life is a valuable predictor of low protein intake.