Challenges for preterm infants

There are many challenges that preterm infants are faced with that can have long-term impacts on their health. The short-term effects in terms of physiology, microbiota dysbiosis and the effects on the immune system will collectively impact long term growth and development. If growth rates in preterm infants are too slow, this will increase their risk of faltering growth, cognitive impairment and disabilities. On the other hand, if growth rates are too rapid, this will increase their risk of non-communicable disease such as obesity, diabetes, cardiovascular disease (CVD) and reduced bone density in later life.

Challenges associated with preterm infants^1,2

• Lower immune system response
• Susceptible to infection
• More vulnerable
• Delayed colonisation with good bacteria
• Immature renal function
• Immature gastrointestinal gut
• Lower body reserve

Gastrointestinal function and feeding challenges³

Feeding challenges must be overcome to prevent growth failure. Such challenges include:

1. Small stomach – limits the amount of feed that can be given at any one time
2. Immature gut and metabolic system – the digestion and absorption of nutrients from feeds may be less efficient because not all enzymes have reached full activity
3. Limited nutrient reserves and low body fat stores due to preterm delivery
4. Weak and uncoordinated intestinal peristalsis – increases the risk of gastric residues and constipation 
5. Uncoordinated latching, suckling, swallowing and breathing 

Gut microbiota in preterm infants

Preterm infants have a less diverse range of gut microbiota, compared to healthy full-term infants. Gut colonisation is significantly influenced by gestational age. This lack of microbial diversity is due to a variety of reasons including⁴:

• C-section 
• Rapid vaginal deliveries 
• Antibiotics
• Invasive procedures 

Bifidobacteria are the first colonisers of a healthy gut, preterm infants typically have lower levels of Bifidobacteria and increased levels of potentially harmful bacteria. This places preterm infants at risk of developing an unfavourable microbiota composition, which in turn can increase their risk of infection and a weakened immune system⁴. 

Prebiotic oligosaccharides in breastmilk encourage the growth of friendly bacteria. The fermentation of prebiotic oligosaccharides produces SCFAs (short-chained fatty acids) as by-products. These SCFAs have shown to have a number of benefits⁵:

• Lower the pH in the gut – this encourages the growth of other friendly bacteria that prefer acidic conditions (i.e. a low pH), and inhibits the growth of pathogenic bacteria 
• Promote a thicker mucous layer in the intestine which reduces inflammation and supports the protective barrier 
• Stimulates intestinal motility which helps prevent constipation and discomfort  

Preterm infants, particularly those who are born ELBW or VLBW are at an increased risk of necrotising enterocolitis (NEC), which is a potentially fatal inflammatory disease of the bowel, in which the affected area of the bowel begins to die. Causes of NEC are multifactorial, with microbiota overgrowth thought to be one of the major factors of its aetiology. Preterm infants also have an immature gut which may impact their risk of this condition. The components of breastmilk, including its prebiotic oligosaccharide make up, protects preterm infants against NEC⁶.   

Preterm infants are faced with many challenges having been brought into the world before they were ready. As HCPs, it is crucial to be aware of these potential challenges and of the mechanisms that could help in reducing the impact of these, both in the short and long term.