Nutrient Needs and Feeding of Premature Infants: Clinical practice guidelines prepared by The Scientific Review Subcommittee of The Nutrition Committee of The Canadian Paediatric Society The previous Canadian Paediatric Society ‘Premature Infant Feeding Statement’ was published in 19811. Since that time, there have been enormous advances in the type and quality of clinical care offered to infants born prematurely. It was therefore appropriate for a subcommittee of the Nutrition Committee of the CPS to write new nutrition recommendations for preterm infants2. The subcommittee included neonatologists, clinical nutritionists and dietitians. For most nutrients it was not possible to derive nutrition recommendations for preterm infants using established research methods for defining nutrient requirements (i.e. factorial analyses, nutrient balances, controlled studies and epidemiologic data). The data simply did not exist. For the full-term infant, human milk is the ‘gold standard’ for setting nutrient requirements. It is not, however, a priori , the reference standard for the premature infant since when it is used without fortification, there is increased risk of inadequate growth and nutrient deficiencies. The committee therefore had to come up with a different method to establish nutrition recommendations. To accomplish this task, specific outcome goals for each nutrient were pre-determined. The outcome goals depended on the birth weight and post-conceptional age of the infant. According to this principle, two birth weight groupings (<1000 g and >l000 g) and three post-conceptional age categories (transitional - birth to 7 days; stable and growing; and, post hospital-discharge) were defined. The birth weight groupings reflect the difference in in-uteroaccretion of nutrients prior to birth, while the postnatal groupings reflect the changing growth and nutrient metabolism with postnatal maturation. The first of the three postnatal groupings was the ‘transition stage’ which was arbitrarily defined as the period between birth and 7 days of age. During this stage infants are likely to be clinically and metabolically unstable (particularly those <1000 g birth weight) and to lose weight, primarily due to shifts in water balance and relative starvation. The minimum achievable goal during this stage was defined as is the provision of nutrients (by the parenteral or enteral route) in amounts that will prevent nutrient deficiencies and substrate catabolism. If the infant is stable, higher intakes can be provided during the later part of the transition period. The second postnatal age category is the ‘stable-growing stage’ . It begins when the infant is metabolically and clinically stable and lasts until the infant is discharged from the level II or III Neonatal Intensive Care Unit (NICU). During this period the primary nutritional goal for the infant is growth and nutrient retention at a rate similar to that which would have been achieved had the infant remained in utero. The final postnatal age category is the ‘post-discharge stage’ which lasts for approximately one year from hospital discharge. During this period a nutrient intake that is adequate to achieve catch-up growth is the stated goal. It should be noted that setting recommendations for this period was hampered by a marked lack of research. The nutrient intake needed to achieve these specific outcome goals was defined as the ‘preterm - recommended nutrient intake’ (P-RNI) (Table I) . When inadequate information was available to establish a P-RNI, a ‘best estimate for safety and efficacy’ was established. Estimates for safety and efficacy were based on a combination of the estimated nutrient intake from preterm mother’s milk (milk produced by the mother of a preterm infant for her own infant, as distinguished from banked human milk) when fed at recommended volumes, combined with clinical studies of efficacy where available. Based on the P-RNI for each nutrient, calculations on the adequacy of preterm mother’s milk and premature formula to achieve these goals were completed. Few studies have examined the long-term outcomes of infants fed various nutrient sources via various routes. Estimates of need, therefore, were for the most part based on short-term outcome responses. The data base from which the recommendations were derived included much more information on infants with birth weights >1000 g (studies completed in the 1980’s and early 1990’s) than on extremely low birth weight (ELBW) infants. Thus, for many nutrients, estimates for intake for ELBW infants were based on an extrapolation from data collected on larger premature infants. By definition therefore, these recommendations must be considered more tentative than those for larger infants. As more data are collected, the ‘strength’ of the recommendations for intake will likely improve. The guidelines are intended to educate health care professionals about neonatal nutrition and to assist them in making informed decisions regarding infant foods and feeding; to provide background information for government officials regulating infant foods; and to stimulate the infant food industry to manufacture feeding products that continue to meet the needs of premature infants. Whenever possible, the hierarchy of evidence for recommendations was balanced in favour of randomized controlled trials. Where RCTs were unavailable, matched cohort studies were considered. When neither were available, data in the literature was reviewed and a consensus of opinion led to recommendations. The recommendations are in line with, but not identical to recent American and European guidelines3,4. Feeding the Infant Born Prematurely The CPS Nutrition Committee recommends fortified preterm mother’s milk or alternatively, preterm formula as the enteral feeding of choice for the premature infant. This recommendation applies to neonates with birth weights < 1800 - 2000g or gestational age <34-38 wks (at this age the infant is often able to nurse effectively) . The benefits of fortified preterm mother’s milk or the need for a preterm formula become less apparent as the neonate approaches full-term weight and gestation, although an exact weight or gestational age cut-off cannot be clearly defined. An exception to this general rule would be for larger premature infants who are fluid restricted or growing poorly when fed unfortified preterm mother’s milk. For infants <1800g, if preterm mother’s milk is available, it may be used without fortification until full enteral feeding has been established in the ‘stable-growing period’. Once full volume enteral feeding has been established, preterm mother’s milk should be fortified with an additional source of nutrients. If preterm mother’s milk is unavailable, preterm formula is recommended from the initiation of enteral feeding. References 1. Nutrition Committee, Canadian Paediatric Society. Feeding the low birth weight infant. Can Med Assoc J 1981;124:1301-11.
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