Protein Intake and Growth in Extremely Low Birthweight Babies

Abstract

The postnatal growth rates of extremely low birthweight (ELBW) babies rarely match those of a fetus who remains in utero. Current international consensus recommendations suggest higher protein intakes are necessary to avoid postnatal growth faltering and improve clinical and neurodevelopmental outcomes, but this remains to be demonstrated in appropriate studies. The aims of this thesis were to monitor protein intakes and postnatal growth in a cohort of 50 ELBW babies in the neonatal unit at National Women’s Health, Auckland City Hospital, to review unit nutritional policies and identify causes of any areas of nutritional care that did not meet international recommendations, to identify, formulate and implement nutrition policy changes to correct the identified deficiencies, and to investigate the effects of these policy changes on protein intakes and postnatal growth in a second cohort of 50 ELBW babies. ELBW babies were identified in National Women’s Health neonatal unit. Policy changes were introduced in collaboration with Newborn Services. All data were collected prospectively. Nutrient intakes and growth were compared between the first (Lo Pro, n = 50) and second (Hi Pro, n = 50) cohorts with Student’s t-test or the Wilcoxon Rank Sum test. Protein intakes and postnatal growth trajectories in the first cohort were below recommended levels. Following implementation of the nutritional policy changes, protein intake was significantly higher in the first month of life (Hi Pro 3.8 ± 0.3; Lo Pro 3.3 ± 0.4 g/Kg.d, p<0.0001). Hi Pro babies had a greater growth velocity over the first 30 days, after regaining birthweight (19.5 ± 5.0 vs.16.2 ± 5.4 g/Kg.d, p<0.002) and significantly lesser Zscore decreases between birth and discharge for weight (0.0 ± 1.3 vs. -0.9 ± 1.1, p<0.0005), crown heel length (-0.8 ± 0.8 vs. -1.2 ± 1.1, p=0.02) and head circumference (0.2 ± 1.1 vs. - 1.1 ± 1.6, p<0.003). Protein intakes in the first month of life in ELBW babies can be increased through simple nutritional policies, resulting in increased growth velocity and significant reductions in the downward crossing of centiles for weight, length and head circumference that commonly occur between birth and discharge.