The goals of this study were to describe nutritional practices in the first month of life for a large cohort of extremely low gestational age newborns and to determine the impact of these nutritional practices on growth velocity over the same period.
The sample included 1187 infants born at 23 weeks to 27 weeks of gestation, at 14 institutions, between 2002 and 2004. Inclusion criteria included survival until day 28 and weight information for both day 7 and day 28. Growth velocity, expressed as grams per kilogram per day (g/kg/day), was calculated for the interval between days 7 and 28. Nutritional practices during the first week and on days 14, 21, and 28 were compared to current nutritional guidelines in the literature. Multivariable logistic regression models estimated the contribution of limited nutrition to limited growth velocity.
Protein and fat delivery approximated current nutritional recommendations while carbohydrate and total caloric delivery did not. Despite this, growth velocity of our study infants exceeded the current guideline of 15 g/kg/day. Nevertheless, we found extrauterine growth restriction (i.e., weight for gestational age below the 10th centile) in 75% of infants at 28 days, as compared to only 18% at birth. A growth velocity of 20-30 g/kg/day was associated with infants' maintaining or exceeding their birth weight Z-score, with rates in the upper range for the gestationally youngest infants. Early (day 7) nutritional practices were positively associated with growth velocity measured between days 7 and 28.
The early provision of nutrients is an important determinant of postnatal growth. Extrauterine growth restriction remains high in extremely premature infants even when they achieve a growth velocity rate within current guidelines.
Keywords: Infant, premature; nutrition; growth velocity