Nutrient intakes independently affect growth in extremely preterm infants: results from a population-based study

Aim: To explore associations between energy and macronutrient intakes and early growth in extremely low gestational age (ELGA) infants.

Methods: Retrospective population-based study of all ELGA infants (<27 weeks) born in Sweden during 2004-2007. Detailed data on nutrition and anthropometric measurements from birth to 70 days of postnatal age were retrieved from hospital records.

Results: Study infants (n = 531) had a mean ± SD gestational age of 25.3 ± 1.1 weeks and a birth weight of 765 ± 170 g. Between 0 and 70 days, average daily energy and protein intakes were 120 ± 11 kcal/kg and 3.2 ± 0.4 g/kg, respectively. During this period, standard deviation scores for weight, length and head circumference decreased by 1.4, 2.3 and 0.7, respectively. Taking gestational age, baseline anthropometrics and severity of illness into account, lower energy intake correlated with lower gain in weight (r = +0.315, p < 0.001), length (r = +0.215, p < 0.001) and head circumference (r = +0.218, p < 0.001). Protein intake predicted growth in all anthropometric outcomes, and fat intake was positively associated with head circumference growth.

Conclusion: Extremely low gestational age infants received considerably less energy and protein than recommended and showed postnatal growth failure. Nutrient intakes were independent predictors of growth even after adjusting for severity of illness. These findings suggest that optimized energy and macronutrient intakes may prevent early growth failure in these infants.