Early Nutrition and Postnatal Brain Growth in the Preterm Infant

Abstract

Preterm infants often show neurodevelopmental deficits in later life. Apart from cerebral palsy and sensory problems, they may have minor motor impairment, attention deficit, visual, perceptional, and learning difficulties. There is disagreement as to whether their learning difficulties are specific or simply part of a generalized lower cognitive ability. While some preterm infants are also growth restricted in utero, the majority are not, and are born appropriately grown. Postnatal growth failure is commonly seen, and appears to be due to problems in ensuring adequate energy and protein intake in the early weeks after birth. In those infants who have poor early growth, failure to show catch-up growth later is associated with lower cognitive ability in childhood. The human brain undergoes a growth spurt between the last trimester of gestation and about 2 years, which is maximal at around full term. During this period it is at its most vulnerable, and nutritional deficiencies may cause changes that cannot be reversed subsequently. Although the head circumference is a good guide to brain size, the availability of MRI allows precise estimates not only of brain size, but also the size of various regions of the brain, and can give an indication of the relative amounts of gray and white matter and ventricular volumes. This technique has been used in preterm infants at term and later in childhood to study the correlation between poor postnatal growth of the brain and developmental problems. A number of clinical trials have attempted to show the effects of improved early nutrition on later developmental outcome. None is entirely satisfactory, but they do indicate a tendency for better outcomes with higher energy and protein intakes. Optimal nutrition for the most preterm has yet to be achieved.