Recent decades have seen a greater survival rate of infants
who are born extremely premature; however, many of
these babies experience extrauterine growth delay. While
maintaining a postnatal growth trajectory similar to the
gestationally equivalent fetus in utero is the standard of
care, there is significant controversy over whether this is
an appropriate goal. Such a growth trajectory is difficult
to achieve, and extrauterine growth restriction is still
common among premature infants, even after they
achieve the goal growth velocity.5–7 This may be the result
of insufficient provision of protein and energy for the
metabolic requirements of these infants. The use of fortified
maternal milk, preterm formulas, and specialized
amino acid preparations has improved postnatal growth
indices and parameters associated with neurodevelopment
and brain growth.8–12 However, the use of these
specialized feedings has also been associated with accretion
of greater body fat relative to weight at termcorrected
age13 as well as increased deposition of visceral
adipose.14
A further contribution is limitations in the ability of
the preterm infant to absorb nutrients.15–17 Nutrient
absorption for the preterm infant could be decreased
because of the preterm infant’s underdeveloped gastrointestinal
tract and accompanying microflora. The
microbiota found in the human gastrointestinal tract is
diverse, dynamic, and likely aids in processes that result in
the maturation of the innate and adaptive immune systems.18
The GI tract of the premature infant has a thin
layer of immature epithelial cells that overlies a highly
immunoreactive submucosa. The premature infant’s
microbiota formation has been shown to be dependent
on the microbes that first colonize the GI tract within the
first several days after birth, with a healthy microbiota
being critical for normal development. Factors that affect
the infant’s microbiota include mode of delivery, delayed
enteral feeding, being exposed to pathogens within the
NICU, and being exposed to a mother’s oral and skin
microbiota and breast milk.19–21
Given the complexity of the neonate’s nutritional
dilemmas, the difficult question that still remains is how
to maximize neurodevelopment and appropriate extrauterine
growth in this sensitive population and is the
subject of much controversy. Clinical studies in humans
and studies in animal models, however, demonstrate that
both the dietary composition and the resultant growth
trajectory affect long-term outcomes.
Recent decades have seen a greater survival rate of infantswho are born extremely premature; however, many ofthese babies experience extrauterine growth delay. Whilemaintaining a postnatal growth trajectory similar to thegestationally equivalent fetus in utero is the standard ofcare, there is significant controversy over whether this isan appropriate goal. Such a growth trajectory is difficultto achieve, and extrauterine growth restriction is stillcommon among premature infants, even after theyachieve the goal growth velocity.5–7 This may be the resultof insufficient provision of protein and energy for themetabolic requirements of these infants. The use of fortifiedmaternal milk, preterm formulas, and specializedamino acid preparations has improved postnatal growthindices and parameters associated with neurodevelopmentand brain growth.8–12 However, the use of thesespecialized feedings has also been associated with accretionof greater body fat relative to weight at termcorrectedage13 as well as increased deposition of visceraladipose.14A further contribution is limitations in the ability ofthe preterm infant to absorb nutrients.15–17 Nutrientabsorption for the preterm infant could be decreasedbecause of the preterm infant’s underdeveloped gastrointestinaltract and accompanying microflora. Themicrobiota found in the human gastrointestinal tract isdiverse, dynamic, and likely aids in processes that result inthe maturation of the innate and adaptive immune systems.18The GI tract of the premature infant has a thinlayer of immature epithelial cells that overlies a highlyimmunoreactive submucosa. The premature infant’smicrobiota formation has been shown to be dependenton the microbes that first colonize the GI tract within thefirst several days after birth, with a healthy microbiotabeing critical for normal development. Factors that affectthe infant’s microbiota include mode of delivery, delayedenteral feeding, being exposed to pathogens within theNICU, and being exposed to a mother’s oral and skinmicrobiota and breast milk.19–21Given the complexity of the neonate’s nutritionaldilemmas, the difficult question that still remains is howto maximize neurodevelopment and appropriate extrauterinegrowth in this sensitive population and is thesubject of much controversy. Clinical studies in humansand studies in animal models, however, demonstrate thatboth the dietary composition and the resultant growthtrajectory affect long-term outcomes.
การแปล กรุณารอสักครู่..
