Nutrition Practices and Predictors of Postnatal Growth in Preterm Infants During Hospitalization

Abstract

Premature infants are at high risk of undernutrition and extrauterine growth restriction (EUGR). To evaluate the relation between nutrition practices and growth rate in preterm infants from birth to 36 weeks postmenstrual age (PMA). Longitudinal data were collected retrospectively in 103 infants born <33-weeks gestation admitted to Dunedin NICU, New Zealand. Weight, length and head circumference at birth and 36-weeks PMA z-scores were calculated using the INTERGROWTH Preterm Growth Standard. Growth velocity (GV; g/kg/day) was determined via exponential model. Time to regain birth weight and nutritional practices including enteral nutrition, withholding feeds, nutrient intake and feeding at discharge were described. Regression was used to explore associations between growth and nutritional variables. Growth faltering (weight-for-age z-score<-1.28/10th centile) increased from 9% at birth to 19% at 36-weeks PMA. Mean (SD) GV in-hospital [14.2 (3.3) g/kg/d] was well below the desirable rate of 18 g/kg/d. Forty-one percent of infants had feeds withheld, which was significantly associated with a longer time period to achieve full enteral feedings (P<0.001) and poorer weight and length z-score at 36 weeks PMA (both P < 0.05). The day of life to establish full enteral feedings was longer than recommended yet positively associated with weight at 36 weeks PMA (P = 0.019), while controlling for withholding feeds and other known confounders. EUGR was highly prevalent in this population. The negative association of withholding of feeds on growth reinforces the need to evaluate early life feeding protocols and further assess the longer term influence of this practice on post-discharge growth outcomes.