[Multicenter study of the nutritional status of premature infants in neonatal intensive care unit in China: report of 974 cases].

OBJECTIVE: Extrauterine growth restriction in preterm infants secondary to suboptimal nutrition is a major problem in neonatal intensive care units (NICUs). This study was designed to investigate the nutritional support and growth of premature infants who were discharged from 10 tertiary NICUs in different areas in China and evaluate the effects of high risk factors on their growth.

METHODS: Data of 1000 premature infants (100 infants from each hospital) were retrospectively collected, the data included their gestational age, the growth parameters at birth, complications, enteral and parenteral nutritional support strategies, the growth parameters at discharge and length of hospital stay from Jan. 1, 2005 to Jun. 30, 2006. The growth parameters, including body weight, length and head circumference, were evaluated according to growth curve of newborns in China with their gestational age at birth and corrected gestational age on discharge. Growth retardation was defined as less than the 10th percentile of the expected value. The risk factors which might result in growth retardation of premature infants were assessed with logistic regression. P < 0.05 was considered as significant.

RESULTS: Of the 1000 premature infants enrolled in this study, the data of 974 premature infants were finally eligible. The median gestational age of the 974 premature infants was 32.6 (31.0-34.1) weeks and median birth weight was 1732.2 (1447.9-2030.3) g. Three hundred and seventy-eight premature infants were born at < 32 weeks of gestational age and the body weight of 285 premature infants was < 1500 g at birth. The median time for initial enteral feeding was 2.0 (1, 3) days of life, 77.0% of the premature infants were fed with formulas for low birth weight, and 13.6% were fed with human milk mixed with the formulas for low birth weight. For parenteral nutrition, amino acid solutions were administered in 87.3% of premature infants and median time to begin was 2.5 (2, 3) days of life, median duration of administration was 11 (6, 17) days. Lipid emulsions were supplied in 56.9% of premature infants and median time to begin was 3 (2, 5) days of life, median duration of administration was 12 (7, 18) days. During hospital stay, 74.1% of the premature infants achieved recommended diet indexes of 120 kcal/(kg.d) (including both enteral and parenteral intakes) and mean time for achieving was (16.3 +/- 9.4) days of life, 84.1% of the premature infants reached enteral feeding of 100 kcal/(kg x d) and the mean time to achieve was (17.0 +/- 9.4) days of life. The lower the gestational age of premature infants was, the longer the time for achieving these goals was. Mean loss of weight was 7.54% +/- 4.7% of birth weight and the day for regaining to birth weight was (10.92 +/- 5.10) days. The lower the gestational age at birth, the more the loss of weight, and the longer the time for regaining to birth weight. Mean growth velocity after regaining to birth weight during hospital stay was (13.4 +/- 6.0) g/(kg x d). Mean length of hospital stay was (26.4 +/- 12.9) days. Of the 696 singletons, 60.0%, 58.9% and 29.5% of the infants had growth retardation by weight, length and head circumference respectively on discharge, while the morbidity increased by 32.7%, 30.9% and 10.2%, respectively, compared with those at birth.

CONCLUSIONS: Morbidity of growth retardation was high among premature infants at birth by weight, length and head circumference. Such growth retardation was further worsened before discharge. Birth weight below the 10th percentile of expected value, later introduction of enteral feeding and lower growth velocity during hospital stay were risk factors for postnatal growth retardation of premature infants. More aggressive nutritional support strategy needs to be considered for improving the nutritional status and development of premature infants in China.