The survival rate for children born prematurely has increased substantially during the last two decades due to improved care and nutrition. Nowadays it is widely recognized that preterm infants have special nutritional needs. The major nutritional goal for these infants is to achieve growth similar to fetal growth, together with adequate functional development.

Growth and nutritional needs of preterm infants 1Growth of premature infants

Human fetal growth is most rapid during the last trimester of pregnancy, a period when preterm infants are no longer in utero. According to the Barker hypothesis, the role of nutrition during this stage of life may be of great importance for later health.1

Growth restriction is a major clinical problem for prematurely born infants, especially for those who are critically ill. Nutritional support of the preterm infant should therefore aim at growth approximating that of a normal fetus of the same postconceptional age.2  To prevent long-term growth restrictions, suboptimal nutrition needs to be detected early and corrected.2 Closely monitoring the growth pattern of a premature infant with an appropriate growth chart is therefore of special importance.3

Nutrient recommendations

Many studies have been performed to discover which nutrients are most important during the growth of a preterm infant and at what levels they should be provided. In 2010, the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESGPHAN) issued detailed advice for the intake of energy, fluids and macro- and micronutrients,2 which clearly mirror the specific and usually higher nutrient needs of preterm infants (table 1). The reasons for these often higher needs are many, for example low reserves, incomplete absorption due to immature metabolism and rapid growth.4,5  While insights have greatly improved, the scientific basis on the nutritional needs for preterm infants is still developing, as is reflected in ongoing changes in nutritional recommendations for this group of infants.

Table 1. Selected key nutrient recommendations by ESPGHAN2,6

  Normal infants* Preterm infants
Energy (kcal/100 ml) 67-70 110-135
Protein (g/100 kcal) 1.8-3 3.2-3.6**
Carbohydrates (g/100 kcal) 9.0-14.0 10.5-12.0
Lipids (g/100 kcal) 4.4- 6.0 4.4-6.0
Vitamin A (mcg RE***/100 kcal) 1.4-1.5 1.8-1.9
Vitamin D (mcg per kg/day) n.a. 20-25
Iron (mcg/100 kcal) 0.3-1.3 1.8-2.7
Copper (mcg/100 kcal) 35-80 90-120

*Based on the recommended composition of standard infant formulae
** 1-1.8 kg body weight
*** Retinol equivalents

Recommended feeding practice

The preferred choice for feeding preterm infants – according to the ESPGHAN-guidelines – is a multi-nutrient fortified breast milk, as unfortified breast milk has been found to supply suboptimal levels of protein as well as selected vitamins and minerals, such as calcium and phosphate.4  The specific nutrients for fortification and the optimal levels are however still topic of discussion. As the composition of breast milk and the infant’s needs both depend on many factors, individualized fortification through targeted or adjustable fortification has recently been suggested by Arslanoglu in the Journal of Perinatal Medicine.7 After discharge from the hospital, fortification of breast milk is still recommended when the infant’s growth is suboptimal.8

When breast milk is not available, special formulae for preterm infants are recommended by the ESPGHAN during hospital stay. Although these formulaes are adapted to the special nutrient needs of preterm infants, the nutrient status and feeding regimes of the preterm infant should -also in this case- be closely monitored and tailored to their individual needs. When normal weight for age is reached by the time of hospital discharge, the ESPGHAN recommends breast feeding or when this is not available, normal formulae with added LCPUFA. Special post-discharge formulae is advised for infants with a suboptimal weight.8

Currently it is common practice in many parts of the world to feed the smallest infants with a birth weight <1,500 g with parenteral solutions. This has greatly facilitated the ability to approach the requirements for growth in these very low birth weight (VLBW) infants in their earliest days of life.9

References

  1. Tamashiro KL, Moran TH. Perinatal environment and its influences on metabolic programming of offspring. Physiol Behav. 2010;100(5):560-6.
  2. Agostoni C et al. Enteral Nutrient Supply for Preterm Infants: Commentary From the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition Committee on Nutrition. JPGN 2010;50:85–91.
  3. Rao SC, Tompkins J; World Health Organization. Growth curves for preterm infants. Early Hum Dev. 2007 Oct;83(10):643-51.
  4. Schanler RJ. Evaluation of the evidence to support current recommendations to meet the needs of premature infants: the role of human milk. Am J Clin Nutr 2007;85(suppl):625S–8S.
  5. Embleton ND. Optimal nutrition for preterm infants: Putting the ESPGHAN guidelines into practice.Journal of Neonatal Nursing 2013:19(4):130–133
  6. Koletzko B et al. Global standard for the composition of infant formula: recommendations of an ESPGHAN coordinated international expert group. J Pediatr Gastroenterol Nutr. 2005;41(5):584-99.
  7. Arslanoglu S et al. Optimization of human milk fortification for preterm infants: new concepts and recommendations. Journal of Perinatal Medicine. 2010;38(3):233–238.
  8. Aggett PJ et al. Feeding Preterm Infants After Hospital Discharge. A Commentary by the ESPGHAN Committee on Nutrition. Journal of Pediatric Gastroenterology and Nutrition 2006;42:596-603.
  9. Greer FR et al. Feeding the Premature Infant in the 20th Century. Nutr. 2001;131:426S–430S.