Brief Summary of Newborn Nutrition

Nutritional sufficiency of the newborn is a topic that continues to engage great debate. Delivery of the fetus is marked by the abrupt transition from the fetal nutritional state. This state is marked by a relatively constant supply of nutrients via the maternoplacental circulation, supplemented to a minor degree by enteral absorption of nutrients derived from swallowed amniotic fluid. The transition to an intermittent and wholly enteral route for neonatal nutritional needs is a critical aspect of successful adaptation at birth.

Breast Feeding and Human Milk
During the last century, the almost exclusive use of human milk was abandoned for a time by some in favor of the fashionable (and occasionally truly necessary) use of cow milk“based formula fed by bottle in developed countries. Over the past 50 years, however, most authorities on infant nutrition the (the American Academy of Pediatrics, among others) have advocated human milk for healthy term babies. This recommendation reflects the results of the vast literature supporting breast-feeding and the use of human milk as a superior form of nutrition for infants. The psychological, nutritional, hormonal, immunologic, and economic benefits of human milk are now well established.

Optimal Newborn Nutrition
Because breast-feeding and ingestion of human milk provide optimal intakes of water and nutrients for growth of healthy term newborns over the first months of postnatal life, growth and developmental patterns of infants reared exclusively on human milk have become the benchmarks by which alternative forms of enteral and parenteral nutritional programs are assessed. Guidelines for optimal intakes of energy, major nutrients, minerals, and water in infancy derive from a variety of sources, including direct experimental observations, such as those involving studies of nutrient balance (ie, protein, fat, calcium), energy expenditure, and metabolic rate as well as those involving more indirect estimates based on measurements of known intakes in healthy term infants (ie, trace minerals, vitamins).

Energy Requirments
Estimates for neonatal energy needs derive in part from indirect estimates of human fetal oxygen consumption in late gestation as well as postnatal assessment of metabolic rate using direct and indirect calorimetry and measurement of respiratory gas exchange. In general, most estimates suggest a basal consumption rate of 7 to 8 mL of O2/kg/min, which translates into approximately 50 kcal/kg body weight/d.

In the first month of postnatal life, total energy intake in breast-fed babies (100 kcal/kg/d) is somewhat lower than it is in bottle-fed babies (110-120 kcal/kg/d), possibly because of measured differences in activity level and sleep state between these two groups. Estimates of total energy expenditure (TEE, or basal metabolic needs plus those for metabolic work,physical activity, growth, and thermoregulation purposes) have more recently been measured in babies. With use of stable nonradioactive isotopes (doubly labeled water method), TEE is approximately 60 to 70 kcal/kg/d in breast-fed babies, with somewhat higher values in bottle-fed babies, corresponding to the previously noted differences in energy intake. Thus, caloric intakes below 80 kcal/kg/d are clearly inadequate to provide for accretion of fat and protein (see below). Whether or not excessive caloric intake leads to later obesity or other problems is an unresolved question, and currently no information is available to properly address this issue. Energy needs and expenditures for infants who are small for gestational age are generally higher than for infants of normal size