The last trimester of pregnancy is a period when nutrient stores are built up. The preterm infant does not have these nutrient stores completely and this puts him in a precarious situation. The physical and metabolic immaturity further compromises the nutritional status of the preterm infant.
Nutrient absorption especially of fat and calcium by the immature gastrointestinal tract is impaired. Since renal function is also immature it is not possible to excrete out excess of certain amino acids whose high concentration may damage the liver and brain of the preterm infant.
Thus preterm infants are candidates for nutrient imbalances and require special dietary attention.
The deficiencies which appear in the first few days are those of fat soluble vitamins, calcium, iron and zinc.
Vitamin E deficiency in premature infants is associated with hemolytic anemia. Since the immature digestive system does not absorb fat efficiently, this fat soluble vitamin is not properly absorbed. Water soluble forms of this vitamin are not absorbed easily. Parenteral supplementation is required till they can feed properly through the oral route.
though premature infants have some stores of folate, these stores decline rapidly in premature infants. The lower the birth weight of the infant, more the decline. About 50 microgram per day need to be given. Other B vitamin deficiencies are also seen because of the low quantity of milk the infant consumes. Therefore these vitamins also need to be supplemented.
Premature infants have lower stores of iron and their rapid growth depletes the stores very fast. For this reason breast fed premature infants are given ferrous sulphate drops at a concentration of 2mg/kg body weight at one month of age. Those infants who get a formula need not be given supplements as the formula is fortified.
Infants born 8-10 months before term have only 30% of the calcium which full term infants have. Thus their bone mineralization is not completed and they may suffer from the metabolic bone disease – Osteopenia or the rickets of prematurity. The smaller the infant, the greater the probability of suffering from osteopenia.