Final answer:
Preterm infant formula and fortified human milk are tailored for premature infants because they contain higher protein and carbohydrate levels essential for growth, different fat composition for easier digestion, and they cater to the immature gastrointestinal tract of preterm babies.
Step-by-step explanation:
Preterm infant formula or fortified human milk is specifically designed for premature infants because of their unique nutritional needs during the first year of life. One of the primary reasons for using these specialized formulas is that after the first month, unfortified human milk may contain inadequate protein for the premature infant, which is essential for their growth and development. Secondly, preterm formula contains a higher percentage of carbohydrate as lactose, vital for brain development and to meet the higher energy requirements of a premature infant. Another consideration is that term formula often contains more medium-chain triglycerides than desirable for preterm infants who need a different fat composition for easier digestion and absorption. Finally, preterm formulas are designed for easier absorption than unfortified human milk, accommodating the immature digestive systems of premature infants. Indeed, the gastrointestinal tract of an infant is initially sterile and is gradually colonized by beneficial bacteria after feeding begins, which is pivotal for digestion and overall gut health.