Preterm infants

Preterm nutritional needs and challenges

Preterm infants will face a multitude of challenges including: respiratory complications, poor thermoregulation, problems with gastrointestinal (GI) tract, low body stores of many nutrients and other medical complications⁸.

The final trimester of pregnancy is particularly important for fetal development^9,10. This is a time of extensive development of organs^9,10, immune system^9,10 and the establishment of nutrient stores¹¹ so preterm infants must complete much of this development ex utero¹².

Feeding preterm infants

2010 ESPGHAN guidelines established recommended intakes for all major nutrients². The focus was on enteral intakes in stable, growing preterm infants from a weight of 1-1.8kg².

Key ESPGHAN recommendations

Advantages of breastmilk

Breastmilk is the best source of nutrition for preterm infants and offers many significant benefits to both infant and mother. It provides13:

• Protection from infections
• An improved feeding tolerance
• A reduced risk of necrotising enterocolitis (NEC)
• Digestive enzymes
• Benefits for baby’s gastrointestinal (GI) tract
• Psychological benefits for mum

However, many preterm infants may have higher nutritional requirements than breastmilk alone can provide2,13. The table below highlights the protein requirements of a preterm infant by body weight as stated in the ESPGHAN recommendations2. It highlights the potential gap between the amount of protein needed and the amount of protein breastmilk can provide.

Protein recommendations by body weight

Also, the daily intake volume that the preterm infant can tolerate is often not enough to cover their increased nutritional needs15-17 as the graph below shows:

The differences between the nutrition requirements of a preterm infant and the nutrition provided in breastmilk highlight the requirement for additional supplementation in the form of either a human milk fortifier and/or a protein supplement.

Breastmilk ingredients

Some of the key components of breastmilk, all of which prove beneficial to a preterm infant’s development, include:

• Prebiotic oligosaccharides (OS)
• Beta-palmitate
• Long-chain polyunsaturated fatty acids (LCPs)

The role of prebiotic oligosaccharides

Prebiotic OS are non-digestible oligosaccharides that occur naturally in breastmilk¹⁸. Upon ingestion, they serve a number of functions^19-23:

They first pass through the stomach and small intestine. The prebiotic OS mixture is then metabolised to produce Short Chain Fatty Acids (SCFA) in the large intestine. SCFA promote a thicker mucous layer lining the intestine and also lower pH levels in the intestine.

The presence of prebiotic OS prevents harmful bacteria from attaching to the intestinal lining and entering the bloodstream. They also encourage the growth of friendly bacteria and feed the beneficial bifidobacteria in the gut.

The role of beta-palmitate

Dietary lipids, or fats, provide preterm infants with a large proportion of their energy, with essential fatty acids and lipid soluble vitamins¹³.

The structure of fats in breastmilk consists of a glycerol group with three fatty acids attached, called a triglyceride. When palmitic acid is in the beta (β) position, lipids are metabolized more efficiently by infants²⁴. This provides several beneficial effects, including: better fat absorption, improved calcium absorption, easier digestion and softer stools^24-28.

The role of long-chain polyunsaturated fatty acids

LCPs are important for the healthy development of an infant’s brain^29,30, eyes³¹, and nervous system³².

For preterm infants, LCPs such as docosahexaenoic acid (DHA) and arachidonic acid (AA) are conditionally essential as the third trimester is a critical period for brain growth^33-37.

The ability to make DHA and AA in the body is very limited in the first few months of life^33-35. Preterm infants fed formulas without LCPs develop poor DHA & AA status^38-42. Formula enrichment with the LCPs, DHA & AA is recommended for preterm and post discharge feeding^{2,13,15,16,43,44}.

Conclusion

It is recognised that the preterm infant is particularly vulnerable and has different nutritional needs to the full term infant. Breastmilk is the best source of nutrition and provides significant advantages, including key ingredients such as prebiotics, milk fats and LCPs. However, in instances where breastmilk is not available or the production of breastmilk is not sufficient to meet the preterm infant’s specific requirements, supplementation is recommended.

References

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