Growth and nutritional needs of preterm infants

The survival of small premature infants has markedly improved during the last few decades. Preterm infants are generally discharged from hospital care earlier than before, with body weights far below typical birth weights of healthy term infants. Such infants may require special nutritional regimens or special post-discharge formulae instead of regular nutrition. However, this is a question that is still the subject of ongoing discussion and research.

ESPGHAN-recommendations

While it is agreed that breast milk – fortified for infants with a subnormal weight – is the preferred choice, different opinions exist on the optimal composition of formulae for preterm infants after hospital discharge. In 2006, the European Society for Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) reviewed the available data on feeding preterm infants after hospital discharge. They advise close monitoring of growth during the hospital stay and after discharge, to enable adequate nutritional support. Measurements of length and head circumference, in addition to weight, must be used to identify those preterm infants with poor growth who may need additional nutritional support.

According to ESPGHAN, infants which have an appropriate weight for their postconceptional age at the time of hospital discharge, should be breastfed when possible. When breast milk is not available, these infants should be fed with regular infant formula containing  long-chain polyunsaturated fatty acids (LCPUFA). Infants discharged with a subnormal weight for postconceptional age are at increased risk of suboptimal growth, and in case they are breast fed, the milk should be supplemented with a human milk fortifier to provide an adequate nutrient supply. If formula-fed, such infants should receive special post-discharge formula with relatively high contents of protein, minerals and trace elements, as well as LCPUFA, at least until a postconceptional age of 40 weeks, but probably until 52 weeks postconceptional age (table 1).1

Table 1 Average energy and protein content of standard, post discharge and preterm formula1 and breast milk2

  Standard
formula
Post discharge formula Preterm formula Breast milk
Energy (kcal/100 ml) 67 72-74 80-90 67
Protein (g/100 ml) 1.4-1.5 1.8-1.9 2.2-2.3 1.1
Calcium (mg/100 ml) 35-54 70-80 100-108 30

 

Specific needs

A recent article by Lapillone et al.,3 addresses the specific needs of preterm infants after hospital discharge. They suggest greater amounts of calcium and phosphorus than those in term formula may be needed to improve bone mineralization in preterm infants after hospital discharge.

Also, vitamin A status may be suboptimal in formula-fed, very low birth weight (VLBW) infants for many months after discharge. It has been shown that preterm infants who ingest 900mcg retinol equivalents (RAE) of vitamin A per day for 90 days fail to exhibit adequate plasma vitamin A concentrations, which may be due to immaturity of fat digestion mechanisms. Body iron stores are highly variable at discharge, so in this publication screening is advised for iron deficiency at discharge, and during the first year of life. The American Academy of Pediatrics (AAP) and ESPGHAN recommend preterm infants receive iron supplements for up to 1 year after discharge.3

Cochrane meta-analysis

The many uncertainties and gaps in research on this topic are reflected by the results of the Cochrane meta-analysis from 2011.The included trials (N =10) that compared post-discharge formula versus standard term formula did not find consistent evidence of effects on growth parameters up to 12 to 18 months corrected age. The authors therefore conclude that the current recommendation to prescribe post-discharge formula for preterm infants following hospital discharge is not supported by the available evidence. This meta-analysis however may, according to the authors of the other above mentioned studies, be of limited value due to various methodological restrictions.

Conclusion

According to the experts, further research is needed to determine the specific nutritional needs of (growth restricted) preterm infants during and particularly after their hospital stay.1,3,4  While much is still unclear about the optimal amount and balance of nutrients for preterm infants after hospital discharge, it is generally recognized that preterm infants have special nutritional needs compared to term infants. Breast milk is the preferred option, preferably fortified in case the child has a low weight for age. Standard term formula does not seem to provide adequate amounts of nutrients for optimal growth of formula-fed preterm infants after hospital discharge.

References

  1. 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.
  2. Prentice A. Constituents of human milk. United Nations University. Retrieved April 25, 2013, from http://archive.unu.edu/unupress/food/8F174e/8F174E04.htm
  3. Lapillone A et al. Nutritional Recommendations for the Late-Preterm Infant and the Preterm Infant after Hospital Discharge. J Pediatr 2013;162:S90-100.
  4. Young L et al. Nutrient-enriched formula versus standard term formula for preterm infants following hospital discharge (Review). The Cochrane Collaboration. Published by JohnWiley & Sons, Ltd. Cochrane Database Syst Rev. 2012 Mar 14;3:CD004696. doi: 10.1002/14651858.CD004696.pub4.