Accuracy of preterm infant weight gain velocity calculations vary depending on method used and infant age at time of measurement.

BACKGROUND: We examined preterm infants' weight gain velocity (WGV) to determine how much calculation methods influences actual WGV during the first 28 days of life. METHODS: WGV methods (Average 2-point, Exponential 2-point, Early 1-point, and Daily) were calculated weekly and for various start times (birth, nadir, regain, day 3 and day 7) to 28 days of age for 103 preterm < 1500 gram infants, with daily weights. RESULTS: Range of WGV estimates decreased 10-22 g/kg/day to 15.5-15.8 g/kg/day when the Early 1-point method and the postnatal weight loss phase were excluded. WGV were lower when the postnatal weight loss was included and higher using the early method. WGV calculations beginning at day 7 did not differ from calculations beginning at the nadir. CONCLUSIONS: Variations in WGV calculations were large enough to create difficulties for comparing results between studies and translating research to practice. We recommend that the postnatal weight loss phase be excluded from WGV calculations and clinical studies report weight nadir and weights at day 7 and 28 to allow adequate comparison and translation of findings in clinical practice. The Average2pt method may be easier to calculate at bedside, so we recommend it be used in clinical settings and research summaries. The Early1pt method should not be used to summarize WGV for research.

Safety of a Triple-chamber Bag Parenteral Nutrition in Children Ages up to 24 Months: An Observational Study.

OBJECTIVES: Hypermagnesemia has been reported in preterm neonates treated with commercial pediatric triple-chamber bag (3CB) parenteral nutrition (PN). This postmarketing study was requested by the European Medicines Agency to assess the safety of a 3CB PN product in full-term neonates and children up to 24 months of age. METHODS: This prospective, multicenter, observational study enrolled hospitalized, full-term, newborn infants and children up to 24 months of age receiving >70% of nutrition as PN and requiring ≥50% of nutrition as PN for ≥5 days. All patients received 3CB PN during the study for ≤15 days. The primary outcome was serum magnesium, summarized by age group (0-1, >1-12, and >12-24 months). Secondary outcomes were nutritional intake and adverse events (AEs), including clinically significant abnormal laboratory results and vital signs. RESULTS: A total of 102 eligible patients were included. Median (interquartile range) parenteral magnesium intake was 0.23 (0.18-0.30) mmol ·â€Škg ·â€Šday. Mean serum magnesium showed no consistent changes during treatment in any age group. One moderate and 3 mild AEs of hypermagnesemia were reported in 4 patients (3.9%), all ages 0 to 1 month. Other AEs in >2 patients were hypertriglyceridemia (6.9%), laryngitis (3.9%), hyperkalemia, hypokalemia, hyponatremia, hypophosphatemia, and neonatal hypotension (each 2.9%). Other serum electrolytes were stable, and revealed no safety concerns. CONCLUSIONS: Mean serum magnesium levels were not affected by 3CB PN in full-term neonates and children up to 24 months of age. The risk of hypermagnesemia AEs was low when providing median parenteral magnesium of 0.2 to 0.3 mmol ·â€Škg ·â€Šday in this population.

An Attempt to Standardize the Calculation of Growth Velocity of Preterm Infants-Evaluation of Practical Bedside Methods.

OBJECTIVE: To examine how well growth velocity recommendations for preterm infants fit with current growth references: Fenton 2013, Olsen 2010, INTERGROWTH 2015, and the World Health Organization Growth Standard 2006. STUDY DESIGN: The Average (2-point), Exponential (2-point), Early (1-point) method weight-gains were calculated for 1,4,8,12, and 16-week time-periods. Growth references' weekly velocities (g/kg/d, gram/day and cm/week) were illustrated graphically with frequently-quoted 15 g/kg/d, 10-30 grams/day and 1 cm/week rates superimposed. The 15 g/kg/d and 1 cm/week growth velocity rates were calculated from 24-50 weeks, superimposed on the Fenton and Olsen preterm growth charts. RESULTS: The Average and Exponential g/kg/d estimates showed close agreement for all ages (range 5.0-18.9 g/kg/d), while the Early method yielded values as high as 41 g/kg/d. All 3 preterm growth references were similar to 15 g/kg/d rate at 34 weeks, but rates were higher prior and lower at older ages. For gram/day, the growth references changed from 10 to 30 grams/day for 24-33 weeks. Head growth rates generally fit the 1 cm/week velocity for 23-30 weeks, and length growth rates fit for 37-40 weeks. The calculated g/kg/d curves deviated from the growth charts, first downward, then steeply crossed the median curves near term. CONCLUSIONS: Human growth is not constant through gestation and early infancy. The frequently-quoted 15 g/kg/d, 10-30 gram/day and 1 cm/week only fit current growth references for limited time periods. Rates of 15-20 g/kg/d (calculated using average or exponential methods) are a reasonable goal for infants 23-36 weeks, but not beyond.

Levels of Silicon in Maternal, Cord, and Newborn Serum and Their Relation With Those of Zinc and Copper.

BACKGROUND: Evidence of silicon's importance to health has been gradually accumulating. Nevertheless, there are few studies comparing serum silicon levels in newborns with maternal levels. Likewise, little is known concerning the inter-relation between silicon and other trace elements. OBJECTIVE: The present study evaluated maternal and newborn levels of serum silicon and their relation to those of zinc and copper. METHODS: We measured serum silicon, copper, and zinc in 66 pregnant women, in the umbilical cord of their infants, and in 44 newborns, by atomic absorption spectrophotometry. All the samples were from fasted subjects. RESULTS: Serum silicon level in term newborns (20.6 ±â€Š13.2 µmol/L) was significantly higher than in umbilical cord (8.9 ±â€Š3.5 µmol/L; P < 0.0001). Mean serum silicon level in maternal vein (7.7 ±â€Š3.4 µmol/L) was lower than that in umbilical cord, although differences were not significant. We also found higher levels of zinc (P = 0.008) and lower levels of copper (P < 0.0001) in cord blood compared with maternal blood. Umbilical venous/maternal venous level ratios of zinc, copper, and silicon were 1.5 ±â€Š0.5, 0.2 ±â€Š0.1, and 1.3 ±â€Š0.7, respectively. There was a positive correlation between silicon and zinc levels (r = 0.32), and a negative correlation between copper and zinc levels (r = -0.35). CONCLUSIONS: It seems that there is a positive gradient of silicon from the mother to her fetus. Silicon levels were higher in newborn than in cord blood, and correlated significantly with that of zinc but not copper. Additional investigations are needed to further define the role of silicon and its interaction with other trace elements during the perinatal period.

Electrolyte and Mineral Homeostasis After Optimizing Early Macronutrient Intakes in VLBW Infants on Parenteral Nutrition.

OBJECTIVES: The aim of the present study was to evaluate electrolyte and mineral homeostasis in very-low-birth-weight (VLBW) infants who received high protein and energy intakes with a unique standardized parenteral nutrition solution containing electrolytes and minerals from birth onward. METHODS: Prospective cohort study in 102 infants with birth weight <1250 g. The evolution of plasma biochemical parameters was described during the first 2 weeks of life. RESULTS: During the first 3 days of life, mean parenteral intakes were 51 ±â€Š8 kcal · kg · day with 2.7 ±â€Š0.4 g · kg · day of protein, 1.1 ±â€Š0.2 mmol · kg · day of sodium and potassium, and 1.3 ±â€Š0.2 mmol · kg · day of calcium and phosphorus. Afterwards, most nutritional intakes (parenteral and enteral) met growth requirements. No infant developed a hyperkalemia >7 mmol/L, and a hypernatremia >150 mmol/L occurred only in 15.7% of the infants. In contrast, hyponatremia <130 mmol/L and hypokalemia <3 mmol/L occurred in 30.4% and 8.8% of the infants, respectively. The initial neonatal metabolic acidosis rapidly resolved in most infants and only 2.0% developed a base deficit >10 mmol/L after day 3 of life. Early hypocalcemia <1.8 mmol/L occurred in 13.7% of the infants. In contrast, hypophosphatemia <1.6 mmol/L occurred in 37.3% and hypercalcemia >2.8 mmol/L occurred in 12.7% of the infants. CONCLUSIONS: Increasing early protein and energy intakes in VLBW infants in the first week of life improves electrolyte homeostasis. It also increases the phosphorus requirements with a calcium-to-phosphorus ratio ≤1.0 (mmol/mmol) and the potassium and sodium requirements to avoid the development of a refeeding-like syndrome. These data suggest that the parenteral nutrition guidelines for VLBW infants for the first week of life need to be revised.

Safe and efficient practice of parenteral nutrition in neonates and children aged 0-18 years - The role of licensed multi-chamber bags.

Parenteral nutrition (PN) is recognized as a complex high-risk therapy. Its practice is highly variable and frequently suboptimal in pediatric patients. Optimizing care requires evidence, consensus-based guidelines, audits of practice, and standardized strategies. Several pediatric scientific organizations, expert panels, and authorities have recently recommended that standardized PN should generally be used over individualized PN in the majority of pediatric patients including very low birth weight premature infants. In addition, PN admixtures produced and validated by a suitably qualified institution are recommended over locally produced PN. Licensed multi chamber bags are standardized PN bags that comply with Good Manufacturing Practice and high-quality standards for the finished product in the frame of their full manufacturing license. The purpose of this article is to review the practical aspects of PN and the evidence for using such multi-chamber bags in pediatric patients. It highlights the safety characteristics and the limitations of the different PN practices and provides some guidance for ensuring safe and efficient therapy in pediatric patients.

Intrauterine-like growth rates can be achieved with premixed parenteral nutrition solution in preterm infants.

Growth failure in neonatal intensive care units is a major challenge for pediatricians and neonatologists. The use of early "aggressive" parenteral nutrition (PN), with >2.5 g/(kg ·d) of amino acids and at least 40 kcal/(kg ·d) of energy from the first day of life, has been shown to provide nutritional intakes in the range recommended by international guidelines, reducing nutritional deficit and the incidence of postnatal growth restriction in preterm infants. However, nutritional practices and adherence to recommendations may vary in different hospitals. Two ready-to-use (RTU), premixed parenteral solutions (PSs) designed for preterm infants have been prospectively evaluated: a binary RTU premixed PS from our hospital pharmacy and a commercially premixed 3-chamber bag (Baxter Healthcare). These premixed PSs provide nitrogen and energy intakes in the range of the most recent recommendations, reducing or eliminating the early cumulative nutritional deficit in very-low-birth-weight infants, and avoiding the development of postnatal growth restriction. A further rationale for RTU premixed PSs is that preterm infants require balanced PN that contains not only amino acids and energy but also minerals and electrolytes from the first day of life in order to reduce the incidence of metabolic disorders frequently reported in extremely-low-birth-weight infants during the early weeks of life.

Benefits of a new pediatric triple-chamber bag for parenteral nutrition in preterm infants.

OBJECTIVES: The aim of this study was to evaluate the efficacy, safety, flexibility, and ease of handling and use of the Ped3CB-A 300  mL, the first ready-to-use multichamber parenteral nutrition (PN) system, with optional lipid bag activation, specially designed for administration to preterm infants. MATERIALS AND METHODS: In this prospective, open-label, multicenter, noncomparative, phase III clinical trial, preterm infants were treated with Ped3CB-A for 5 to 10 consecutive days. RESULTS: A total of 113 preterm infants were enrolled in the study and 97 (birth weight 1382 ±â€Š520 g; gestational age 31.2 ±â€Š2.5 weeks; postnatal age administration 5.6 ±â€Š6.1 days) were included in the per protocol analysis accounting for 854 perfusion days. Double-chamber bag activation was used for 32 perfusion days. Macronutrient, electrolyte, and mineral supplements were primarily administered through a Y-line or directly in the activated bag. In all, 199 additions (mainly sodium, 95%) were made to the Ped3CB-A bags on 197 infusion days (23.1%) in 43 infants (44.3%). More than 1 of these nutrients was added to the bag on only 1 perfusion day. Mean and maximum parenteral nutrient intakes were 2.8 ±â€Š0.7 and 3.6 ±â€Š0.8  g amino acids per kilogram per day, and 80 ±â€Š20 and 104 ±â€Š22  kcal · kg(-1) · day(-1). Mean weight gain represented 10.0, 21.5, and 22. 6 g · kg(-1) · day(-1) according to age at inclusion (0-3, 4-7, or >7 days of life). A visual analog scale was completed and produced positive results. No adverse events were attributable to the design of the Ped3CB-A system. CONCLUSIONS: Ped3CB-A provides easy-to-use, well-balanced, and safe nutritional support. Nutritional intakes and weight gain were within the recent PN recommendations in preterm infants.

Reduction in postnatal cumulative nutritional deficit and improvement of growth in extremely preterm infants.

AIM: To evaluate the influence of gestational age (GA) on cumulative nutritional deficit and postnatal growth in extremely preterm (EPT) infants after optimizing nutritional protocol as recently recommended. METHODS: A prospective, nonrandomized, observational study in extremely preterm (EPT, <28 weeks) and very preterm (VPT, 28-30 weeks) infants. RESULTS: Eighty-four infants were included (BW: 978 ± 156 g, GA: 27.8 ± 1.3 weeks). Cumulative nutritional deficit increased during first week of life to -290 ± 84 and -285 ± 117 kcal/kg and -4.2 ± 3.1 and -4.8 ± 3.9 g/kg of protein in EPT and VPT groups, respectively. After 6 weeks, only cumulative energy deficit in EPT group remained significant (p < 0.05) even when 96% of theoretical energy intakes were provided. Weight z score decreased during first 3 days in average with initial weight loss, and then, the z score increased during the first 6 weeks of life in the majority (75%) of infants. Cumulative protein deficit during the first week of life was the major determinant of the postnatal growth during the first 6 weeks of life. CONCLUSION: Cumulative nutritional deficit may be drastically reduced in both EPT and VPT infants after optimizing nutritional policy during the first weeks of life, and the postnatal growth restriction could even be prevented.

Efficacy and Safety of Enteral Recombinant Human Insulin in Preterm Infants: A Randomized Clinical Trial.

IMPORTANCE: Feeding intolerance is a common condition among preterm infants owing to immaturity of the gastrointestinal tract. Enteral insulin appears to promote intestinal maturation. The insulin concentration in human milk declines rapidly post partum and insulin is absent in formula; therefore, recombinant human (rh) insulin for enteral administration as a supplement to human milk and formula may reduce feeding intolerance in preterm infants. OBJECTIVE: To assess the efficacy and safety of 2 different dosages of rh insulin as a supplement to both human milk and preterm formula. DESIGN, SETTING, AND PARTICIPANTS: The FIT-04 multicenter, double-blind, placebo-controlled randomized clinical trial was conducted at 46 neonatal intensive care units throughout Europe, Israel, and the US. Preterm infants with a gestational age (GA) of 26 to 32 weeks and a birth weight of 500 g or more were enrolled between October 9, 2016, and April 25, 2018. Data were analyzed in January 2020. INTERVENTIONS: Preterm infants were randomly assigned to receive low-dose rh insulin (400-µIU/mL milk), high-dose rh insulin (2000-µIU/mL milk), or placebo for 28 days. MAIN OUTCOMES AND MEASURES: The primary outcome was time to achieve full enteral feeding (FEF) defined as an enteral intake of 150 mL/kg per day or more for 3 consecutive days. RESULTS: The final intention-to-treat analysis included 303 preterm infants (low-dose group: median [IQR] GA, 29.1 [28.1-30.4] weeks; 65 boys [59%]; median [IQR] birth weight, 1200 [976-1425] g; high-dose group: median [IQR] GA, 29.0 [27.7-30.5] weeks; 52 boys [55%]; median [IQR] birth weight, 1250 [1020-1445] g; placebo group: median [IQR] GA, 28.8 [27.6-30.4] weeks; 54 boys [55%]; median [IQR] birth weight, 1208 [1021-1430] g). The data safety monitoring board advised to discontinue the study early based on interim futility analysis (including the first 225 randomized infants), as the conditional power did not reach the prespecified threshold of 35% for both rh-insulin dosages. The study continued while the data safety monitoring board analyzed and discussed the data. In the final intention-to-treat analysis, the median (IQR) time to achieve FEF was significantly reduced in 94 infants receiving low-dose rh insulin (10.0 [7.0-21.8] days; P = .03) and in 82 infants receiving high-dose rh insulin (10.0 [6.0-15.0] days; P = .001) compared with 85 infants receiving placebo (14.0 [8.0-28.0] days). Compared with placebo, the difference in median (95% CI) time to FEF was 4.0 (1.0-8.0) days for the low-dose group and 4.0 (1.0-7.0) days for the high-dose group. Weight gain rates did not differ significantly between groups. Necrotizing enterocolitis (Bell stage 2 or 3) occurred in 7 of 108 infants (6%) in the low-dose group, 4 of 88 infants (5%) in the high-dose group, and 10 of 97 infants (10%) in the placebo group. None of the infants developed serum insulin antibodies. CONCLUSIONS AND RELEVANCE: Results of this randomized clinical trial revealed that enteral administration of 2 different rh-insulin dosages was safe and compared with placebo, significantly reduced time to FEF in preterm infants with a GA of 26 to 32 weeks. These findings support the use of rh insulin as a supplement to human milk and preterm formula. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02510560.

Optimizing early nutritional support based on recent recommendations in VLBW infants and postnatal growth restriction.

OBJECTIVE: The aim of this study was to evaluate postnatal growth up to discharge in very low birth weight infants after optimizing nutritional support based on recent nutritional recommendations. PATIENTS AND METHODS: A prospective, nonrandomized, consecutive, and observational study in infants weighing <1250 g. RESULTS: One hundred two infants were included during a 2-year period (birth weight 1005 ± 157 g, gestational age 28.5 ± 1.9 weeks). First-day nutritional intake was 38 ± 6 kcal/kg/day with 2.4 ± 0.3 g/kg/day of protein. Mean intake during the first week of life was 80 ± 14 kcal/kg/day with 3.2 ± 0.5 g/kg/day of protein. On average from birth to discharge, 122 ± 10 kcal/kg/day and 3.7 ± 0.2 g/kg/day of protein were administered. Postnatal weight loss was limited to the first 3 days of life, and birth weight was regained after 7 days in average. Catch-up occurred after the second week in all groups of very low birth weight infants. Small-for-gestational age infants demonstrated an earlier and higher weight gain, allowing a rapid catch-up growth. The same proportion of infants was small-for-gestational age at birth and at discharge (20%, P = 0.74). CONCLUSIONS: This study confirmed that the first week of life is a critical period to promote growth and that early nutrition from the first day of life is essential. Postnatal weight loss may be limited and subsequent growth may be optimized with a dramatic reduction of postnatal growth restriction.

Cost-Consequences Analysis of Increased Utilization of Triple-Chamber-Bag Parenteral Nutrition in Preterm Neonates in Seven European Countries.

The safety of parenteral nutrition (PN) remains a concern in preterm neonates, impacting clinical outcomes and health-care-resource use and costs. This cost-consequence analysis assessed national-level impacts of a 10-percentage point increase in use of industry-prepared three-chamber bags (3CBs) on clinical outcomes, healthcare resources, and hospital budgets across seven European countries. A ten-percentage-point 3CB use-increase model was developed for Belgium, France, Germany, Italy, Portugal, Spain, and the UK. The cost-consequence analysis estimated the impact on compounding error harm and bloodstream infection (BSI) rates, staff time, and annual hospital budget. Of 265,000 (52%) preterm neonates, 133,000 (52%) were estimated to require PN. Baseline compounding methods were estimated as 43% pharmacy manual, 16% pharmacy automated, 22% ward, 9% outsourced, 3% industry provided non-3CBs, and 7% 3CBs. A modeled increased 3CB use would change these values to 39%, 15%, 18%, 9%, 3%, and 17%, respectively. Modeled consequences included -11.6% for harm due to compounding errors and -2.7% for BSIs. Labor time saved would equate to 41 specialized nurses, 29 senior pharmacists, 26 pharmacy assistants, and 22 senior pediatricians working full time. Budget impact would be a €8,960,601 (3.4%) fall from €260,329,814 to €251,369,212. Even a small increase in the use of 3CBs in preterm neonates could substantially improve neonatal clinical outcomes, and provide notable resource and cost savings to hospitals.

"Extrauterine growth restriction" and "postnatal growth failure" are misnomers for preterm infants.

Preterm infants are increasingly diagnosed as having "extrauterine growth restriction" (EUGR) or "postnatal growth failure" (PGF). Usually EUGR/PGF is diagnosed when weight is <10th percentile at either discharge or 36-40 weeks postmenstrual age. The reasons why the phrases EUGR/PGF are unhelpful include, they: (i) are not predictive of adverse outcome; (ii) are based only on weight without any consideration of head or length growth, proportionality, body composition, or genetic potential; (iii) ignore normal postnatal weight loss; (iv) are usually assessed prior to growth slowing of the reference fetus, around 36-40 weeks, and (v) are usually based on an arbitrary statistical growth percentile cut-off. Focus on EUGR/PGF prevalence may benefit with better attention to nutrition but may also harm with nutrition delivery above infants' actual needs. In this paper, we highlight challenges associated with such arbitrary cut-offs and opportunities for further refinement of understanding growth and nutritional needs of preterm neonates.

Time interval for preterm infant weight gain velocity calculation precision.

Calculation of weight gain velocity is used to guide nutrition and fluid management practices in neonatal intensive care units. Calculations over short time periods may be more responsive to management changes, but less precise. Weight gain velocity calculated over 5 to 7+ days have lower variability and less noise than shorter periods.

Growth Benefits of Own Mother's Milk in Preterm Infants Fed Daily Individualized Fortified Human Milk.

The influence of types of human milk (HM)-raw own mother's milk (OMM), pasteurized OMM, and donor milk (DM)-was evaluated for growth in premature infants fed exclusively HM with controlled nutritional intakes using daily individualized HM fortification (IHMF). Growth and nutritional intakes were prospectively collected in preterm infants (<32 weeks) fed IHMF and compared in infants fed predominantly (≥75%) OMM and DM. The influence of HM types (raw OMM, pasteurized OMM, and DM) on growth were also evaluated in the whole population. One-hundred and one preterm infants (birth weight 970 ± 255 g, gestational age 27.8 ± 1.9 weeks) were included. Energy (143 ± 8 vs. 141 ± 6 kcal/kg/day; p = 0.15) and protein intakes (4.17 ± 0.15 vs. 4.15 ± 0.14 g/kg/day; p = 0.51) were similar in both groups. Infants receiving predominantly OMM (n = 37), gained significantly more weight (19.8 ± 2.0 vs. 18.2 ± 2.2 g/kg/day; p = 0.002) and length (1.17 ± 0.26 vs. 0.99 ± 0.36 cm/week; p = 0.020) than those fed predominantly DM (n = 33). Stepwise multivariate analysis (n = 101) suggests that raw OMM was the major determinant of growth, contributing 22.7% of weight gain. Length gain was also related to OMM (raw + pasteurized) intakes, explaining 4.0% of length gain. In conclusion, at daily controlled similar protein and energy intakes, OMM had significant beneficial effects on weight and length versus DM in VLBW infants. This difference could be partially explained by the use of raw OMM.

Use of donor milk in the neonatal intensive care unit.

Own mother's milk is the first choice in feeding preterm infants and provides multiple short- and long-term benefits. When it is unavailable, donor human milk is recommended as the first alternative. Donor milk undergoes processing (i.e. pasteurization) to reduce bacteriological and viral contaminants but influences its bioactive properties with potentially fewer benefits than raw milk. However, there is no clinical evidence of health benefit of raw compared to pasteurized human milk, and donor milk maintains documented advantages compared to formula. Nutrient content of donor and own mother's milk fails to meet the requirements of preterm infants. Adequate fortification is necessary to provide optimal growth. There are significant challenges in providing donor milk for premature infants; therefore, specific clinical guidelines for human milk banks and donor milk use in the neonatal intensive care unit should be applied and research should focus on innovative solutions to process human milk while preserving its immunological and nutritional components. In addition, milk banks are not the only instrument to collect, process and store donor milk but represent an excellent tool for breastfeeding promotion.

Preterm Infant Growth Velocity Calculations: A Systematic Review.

CONTEXT: Clinicians assess the growth of preterm infants and compare growth velocity using a variety of methods. OBJECTIVE: We determined the numerical methods used to describe weight, length, and head circumference growth velocity in preterm infants; these methods include grams/kilogram/day (g/kg/d), grams/day (g/d), centimeters/week (cm/week), and change in z scores. DATA SOURCES: A search was conducted in April 2015 of the Medline database by using PubMed for studies that measured growth as a main outcome in preterm neonates between birth and hospital discharge and/or 40 weeks' postmenstrual age. English, French, German, and Spanish articles were included. The systematic review was conducted by using Preferred Reporting Items for Systematic Reviews and Meta-analyses methods. STUDY SELECTION: Of 1543 located studies, 373 (24%) calculated growth velocity. DATA EXTRACTION: We conducted detailed extraction of the 151 studies that reported g/kg/d weight gain velocity. RESULTS: A variety of methods were used. The most frequently used method to calculate weight gain velocity reported in the 1543 studies was g/kg/d (40%), followed by g/d (32%); 29% reported change in z score relative to an intrauterine or growth chart. In the g/kg/d studies, 39% began g/kg/d calculations at birth/admission, 20% at the start of the study, 10% at full feedings, and 7% after birth weight regained. The kilogram denominator was not reported for 62%. Of the studies that did report the denominators, the majority used an average of the start and end weights as the denominator (36%) followed by exponential methods (23%); less frequently used denominators included birth weight (10%) and an early weight that was not birth weight (16%). Nineteen percent (67 of 355 studies) made conclusions regarding extrauterine growth restriction or postnatal growth failure. Temporal trends in head circumference growth and length gain changed from predominantly cm/wk to predominantly z scores. LIMITATIONS AND CONCLUSIONS: The lack of standardization of methods used to calculate preterm infant growth velocity makes comparisons between studies difficult and presents an obstacle to using research results to guide clinical practice.

Hydrolyzed Proteins in Preterm Infants.

Milk proteins are an essential component of the diet of preterm infants who have high requirements. Hydrolyzed proteins (HPs) have been introduced in infants' formulas (HPFs) to treat gastrointestinal disorders and to prevent allergic diseases. Several studies have evaluated the adequacy of HPs in preterm infants. Protein source significantly influences plasma amino acid concentrations. Protein utilization and efficiency are usually lower with HPFs compared to formulas with intact proteins. When protein intake is similar, a lower weight gain is generally observed with HPFs and a 10% increase in protein content is usually necessary to compensate for this reduction in protein utilization. Mineral absorption may also be reduced and no data exist for trace elements and vitamins. Most HPFs are associated with accelerated gastrointestinal transit time and softer stools but without clear benefit on feeding tolerance. Preterm infants seem to be at similar risk of allergic diseases than term infants, but the preventive effect of HPFs has not been sufficiently explored in preterm infants. Most modern HPFs designed for preterm infants are well tolerated and have adapted their nutrient content to improve nutrient absorption and retention. However, their benefits and safety have not been demonstrated and, therefore, further high-quality studies are needed.