Chapter 11: Nutrition and Growth

I. Intensive care

1. Early nutrition for the very low birthweight infant (VLBW)

   1. Nutritional strategies for VLBW infants should minimize the interruption of growth and development as the fetus transitions to extrauterine life.

   2. The initial phase of management with total parenteral nutrition (TPN) improves growth by

      1. Reducing postnatal weight loss

      2. Promoting earlier return to birthweight (RTBW)

      3. Facilitating catch-up growth

   3. When TPN is used exclusively for the provision of nutrients with no enteral nutrition, morphologic and functional changes occur in the gut including

      1. Significant decrease in intestinal mass

      2. Decrease in mucosal enzyme activity

      3. Increase in gut permeability

   4. The changes are due primarily to the lack of luminal nutrients.

   5. The earlier initiation of enteral feedings has direct trophic effects on the gastrointestinal tract and indirect effects secondary to release of intestinal hormones.

   6. Initiation of TPN with early enteral feedings the first days of life allows feedings to be advanced slowly, which may increase the tolerance and safety of enteral feedings.

2. Postnatal growth failure

   1. Many VLBW infants experience extrauterine growth restriction (EUGR).

   2. Figure 11-1 is based on data from the National Institutes of Child Health and Human Development (NICHD) Neonatal Research Network demonstrating the differences between normal intrauterine growth and the postnatal growth failure among the VLBW infants in the NICHD study.

   3. This “growth faltering” is most common among extremely low birthweight infants (ELBW) (birthweight <1000 g).

   4. Nutrient intakes received by VLBW infants during the first weeks of life in particular are much lower than what the fetus received in utero.

   5. Although nonnutritional factors (comorbidities) contribute to slower growth of these infants, suboptimal nutrient intakes are critical in explaining their poor growth outcomes.

   6. Figure 11-2 suggests that postnatal growth failure or EUGR is a “surrogate” for inadequate nutrition. The observation of postnatal growth failure suggests that inadequate nutrition has taken place and the infant is at risk for poor neurodevelopmental outcomes.

   7. Considerable evidence links inadequate nutrition and long-lasting effects including short stature and poor neurodevelopmental outcomes.

      1. Preterm infants receiving a preterm formula containing more protein and other enrichment, versus a term formula, over the first month of life had higher neurodevelopmental indices at 18 months, 7 to 8 years, and as adolescents. The difference in protein between the two diets was thought to be the important dietary difference as well as taurine found only in breast milk and added to only preterm formula, not term formula. Taurine is neurotrophic and exerts specific neurodevelopmental effects in these infants.

      2. ELBW infants in the NICHD cohort with the highest growth velocity by weight (21.2 g/kg/d) and head circumference (1.17 cm/wk) from RTBW to discharge 12 g/kg/d and 0.67 cm/wk, respectively, had a lower incidence of cerebral palsy, mental developmental index scores >70, and were less likely to demonstrate abnormal neurologic findings at 18 to 22 months corrected age. The lowest growth quartile (12 g/kg/d and 0.67 cm/wk), respectively, had the highest risk for morbidity; therefore, inadequate nutrition is responsible for the poor outcomes observed here.

   8. These studies emphasize the ...