The use of breastmilk in a neonatal unit and its relationship to protein and energy intake and growth

A Systematic Review and Meta-Analysis of Human Milk Feeding and Short-Term Growth in Preterm and Very Low Birth Weight Infants

Human milk (HM) is the gold standard for feeding infants but has been associated with slower growth in preterm infants compared with preterm formula. This systematic review and meta-analysis summarises the post-1990 literature to examine the effect of HM feeding on growth during the neonatal admission of preterm infants with birth weight ≤1500 g and/or born ≤28 weeks’ gestation. Medline, PubMed, CINAHL, and Scopus were searched, and comparisons were grouped as exclusive human milk (EHM) vs. exclusive preterm formula (EPTF), any HM vs. EPTF, and higher vs. lower doses of HM. We selected studies that used fortified HM and compared that with a PTF; studies comparing unfortified HM and term formula were excluded. Experimental and observational studies were pooled separately. The GRADE system was used to evaluate risk of bias and certainty of evidence. Forty-four studies were included with 37 (n = 9963 infants) included in the meta-analyses. In general, due to poor quality studies, evidence of the effect of any HM feeds or higher versus lower doses of HM was inconclusive. There was a possible effect that lower doses of HM compared with higher doses of HM improved weight gain during the hospital admission, and separately, a possible effect of increased head circumference growth in infants fed EPTF vs. any HM. The clinical significance of this is unclear. There was insufficient evidence to determine the effects of an exclusive HM diet on any outcomes.

Preterm infant nutrition and growth with a human milk diet

Human milk is the preferred enteral diet for preterm infants. It provides macronutrients, micronutrients, and bioactive factors that support physical growth and neurodevelopment. Challenges of the human milk diet include the variability in its composition and a need for fortification to mirror placental nutrient delivery and prevent extrauterine growth restriction. Various strategies exist to attain target nutrient provision and optimize growth, including leveraging new technology for point-of-care human milk analysis. When maternal milk is unavailable or in short supply, pasteurized donor human milk is the preferred alternative. Infants fed donor milk may have slower weight gain than those fed exclusively maternal milk or formula, whereas infants fed fortified maternal milk have similar weight gain to preterm formula-fed infants. Future directions include more rigorous characterization of the variation in human milk, further investigation of the clinical benefits of non-nutrient bioactive factors in milk, and novel approaches to optimize fortification.

The association of macronutrients in human milk with the growth of preterm infants

Background

Breast milk is the optimal choice for feeding premature babies. However, the prevalence rate of extrauterine growth restriction in preterm infants remains high.

Objectives

The purpose of this study was to analyze the macronutrients present in human milk and the correlation with the growth of in-hospital preterm infants.

Methods

This prospective study is based on data from 99 in-hospital preterm infants younger than 37 weeks of gestational age on an exclusively human milk diet. Infants who had previously received parenteral nutrition were eligible, but they had to have reached full enteral feeding at the time that the samples were taken. A total of 3282 samples of raw human milk or donor pasteurized milk were collected. The levels of lactose, protein, fat, and energy in the samples were measured using a Miris human milk analyzer. The primary outcome was weight growth velocity (g/kg/day) which was obtained using two-point approach.

Results

The mean (±standard deviation) macronutrient composition per 100 mL of milk was 7.2 (±0.3) g of lactose, 1.1 (±0.2) g of true protein, 3.5 (±0.9) g of fat, and 66.9 (±6.5) kcal of energy. The protein concentration in human milk had a positive, significant correlation with body weight gain, with a coefficient of 0.41 (p < 0.001). After adjusting for gestational age, postmenstrual age, small-for-gestational age, intraventricular hemorrhage, patent ductus arteriosus or congestive heart failure, duration of total parenteral nutrition support, bottle feeding or use of orogastric tube, and ventilator support, total daily protein intake was associated with body weight growth (p < 0.001).

Conclusion

Both the protein concentration in human milk and the daily total protein intake had a positive correlation with the body weight gain of premature infants. Routine analysis of breast milk and individualized fortification might be indicated to optimize the growth of preterm infants.

Assessment of human milk composition using mid-infrared analyzers requires calibration adjustment

OBJECTIVE

Nutrient composition of human milk (HM) is highly variable. Targeted HM fortification has been proposed to address these variations and reduce the cumulative nutritional deficit in preterm infants. Near-infrared analysis is used to measure the protein and fat content in HM; however, the reliability of this technique has not been evaluated. The objective of this study is to evaluate the reproducibility and accuracy of two generations of HM analyzers (HMA1 and HMA2) in estimating protein and lipid contents.

STUDY DESIGN

Reproducibility was assessed by analyzing in duplicate 146 and 128 HM samples with HMA1 and HMA2 (Miris), respectively. To evaluate the accuracy, lipid and protein concentrations were assessed in 31 and 39 samples using HMA1 or HMA2, respectively. Values were compared with measurements obtained using reference methods and correction equations were calculated. After applying the correction equations on 12 HM samples, the performance of the two devices were compared and the equation was validated according to the reference methods.

RESULTS

The coefficients of variation for protein and lipid assessments were below 3% for both HMA1 and HMA2. Protein concentrations were significantly underestimated by HMA2 (-0.53±0.23 g dl^-1). Lipid content was significantly overestimated by both devices, but the error was greater with HMA1 (0.76±0.48 g dl^-1) than with HMA2 (0.36±0.33 g dl^-1). Correction equations were specific for each generation of HMA. Finally, after correction, both instruments provided similar and accurate results.

CONCLUSION

HMAs require calibration adjustment before their use in clinical practice, to avoid inappropriate HM fortification.

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.

Pasteurized human donor milk use among US level 3 neonatal intensive care units

BACKGROUND

Pasteurized human donor milk (DM) is recommended by the World Health Organization and American Academy of Pediatrics for preterm infants when mother's own milk is unavailable, yet the extent and predictors of use and criteria for use in US neonatal intensive care units (NICUs) are unknown.

OBJECTIVE

This study aimed to evaluate current DM use in US level 3 NICUs and predictors and criteria of use.

METHODS

We sent mail surveys to 302 US level 3 NICU directors. We used multivariable logistic regression to analyze predictors of DM use.

RESULTS

Survey response rate was 60%, and 76 of 182 (42%) directors reported DM use. Among DM users, 30% have used DM < 2 years and 55% for 2 to 5 years. Among nonusers, 63% were uncertain of turnaround time when ordering DM, 36% were unclear what guidelines milk banks followed, and 31% were unsure of parent receptiveness. In multivariate analyses, > 800 annual admissions (odds ratio [OR], 4.11; 95% confidence interval [CI], 1.43-11.82; reference ≤ 400 admissions) and location in the Midwest (OR, 3.02; 95% CI, 1.17-7.76) and West (OR, 6.33; 95% CI, 2.28-15.57; reference Northeast) were positively associated with DM use; safety-net hospitals (> 75% Medicaid insurance) were negatively associated (OR, 0.35; 95% CI, 0.14-0.89).

CONCLUSION

Pasteurized human donor milk use is rapidly emerging among US level 3 NICUs. Larger NICUs and those in the West and Midwest were more likely to use DM, while safety-net hospitals were less likely to use DM. Lack of knowledge by medical directors of accessibility, safety, and parental receptiveness may be barriers to DM use.

Report of a Staff Program to Promote and Support Breastfeeding in the Care of Vulnerable Infants at a Children's Hospital

Ill or premature infants do not have the opportunity to begin breastfeeding in an optimal manner; yet, these infants may benefit most from human milk. Health-care providers' knowledge of breastfeeding in both healthy and ill infants is frequently limited due to deficits in training. This article outlines a multifaceted approach to develop a comprehensive, hospital-wide system to support and promote breastfeeding for vulnerable infants. This approach was designed for the staff of the Children's Hospital of Philadelphia.

Longitudinal analysis of macronutrients and minerals in human milk produced by mothers of preterm infants

BACKGROUND & AIMS

The primary objective of this study was to investigate the composition of breast milk of mothers with extremely preterm infants (<28 weeks) for their nutrient content over the first 8 weeks of lactation, and to compare premature to term milk.

METHODS

Breast milk from 102 mothers who had delivered preterm infants and from 10 mothers who had delivered term infants were collected longitudinally. Fat, protein, carbohydrate, minerals and energy content were estimated weekly in each participant. Milk samples were representative of complete 24-h cycles.

RESULTS

Carbohydrate, fat and energy concentrations were significantly higher in preterm than in term milk (p < 0.05). Protein content of both preterm and term milk decreased with the progress of lactation demonstrating significantly higher values in extremely preterm milk (<28 weeks) than in moderately preterm and term milk (p < 0.0001). The sodium levels of preterm milk were significantly elevated (p < 0.05) only in the first week. Other changes in mineral content were detected neither in preterm nor term milk.

CONCLUSIONS

Our data provide new information on the macronutrient content of milk in mothers of extremely preterm infants with possible implications for the nutrition of this population.

The initial maternal cost of providing 100 mL of human milk for very low birth weight infants in the neonatal intensive care unit

OBJECTIVES

Human milk (HM) feeding is associated with lower incidence and severity of costly prematurity-specific morbidities compared to formula feeding in very low birth weight (VLBW; <1,500 g) infants. However, the costs of providing HM are not routinely reimbursed by payers and can be a significant barrier for mothers. This study determined the initial maternal cost of providing 100 mL of HM for VLBW infants during the early neonatal intensive care unit (NICU) stay.

METHODS

This secondary analysis examined data from 111 mothers who provided HM for their VLBW infants during the early NICU stay. These data were collected during a multisite, randomized clinical trial where milk output and time spent pumping were recorded for every pumping session (n = 13,273). The cost analysis examined the cost of the breast pump rental, pump kit, and maternal opportunity cost (an estimate of the cost of maternal time).

RESULTS

Mean daily milk output and time spent pumping were 558.2 mL (SD = 320.7; range = 0-2,024) and 98.7 minutes (SD = 38.6; range = 0-295), respectively. The mean cost of providing 100 mL of HM varied from $2.60 to $6.18 when maternal opportunity cost was included and from $0.95 to $1.55 when it was excluded. The cost per 100 mL of HM declined with every additional day of pumping and was most sensitive to the costs of the breast pump rental and pump kit.

CONCLUSIONS

These findings indicate that HM is reasonably inexpensive to provide and that the maternal cost of providing milk is mitigated by increasing milk output over the early NICU stay.

Improving the use of human milk during and after the NICU stay

The feeding of human milk (milk from the infant's own mother; excluding donor milk) during the newborn intensive care unit (NICU) stay reduces the risk of costly and handicapping morbidities in premature infants. The mechanisms by which human milk provides this protection are varied and synergistic, and appear to change over the course of the NICU stay. The fact that these mechanisms include specific human milk components that are not present in the milk of other mammals means that human milk from the infant's mother cannot be replaced by commercial infant or donor human milk, and the feeding of human milk should be a NICU priority. Recent evidence suggests that the impact of human milk on improving infant health outcomes and reducing the risk of prematurity-specific morbidities is linked to specific critical exposure periods in the post-birth period during which the exclusive use of human milk and the avoidance of commercial formula may be most important. Similarly, there are other periods when high doses, but not necessarily exclusive use of human milk, may be important. This article reviews the concept of "dose and exposure period" for human milk feeding in the NICU to precisely measure and benchmark the amount and timing of human milk use in the NICU. The critical exposure periods when exclusive or high doses of human milk appear to have the greatest impact on specific morbidities are reviewed. Finally, the current best practices for the use of human milk during and after the NICU stay for premature infants are summarized.

Bedside analysis of human milk for adjustable nutrition strategy

AIM

Mother's milk is optimum for preterm infants, but human milk fortifier is required at times, because some nutrients are sometimes insufficient for infant growth. It is important to measure the nutrients in breast milk at bedside so that the amount of nutrients that need to be supplemented can be determined. A human milk analyser (HMA, Miris) is currently available. We examined if the macronutrient values measured by human milk analyser are comparable with those measured by conventional methods. We also sought to discover whether we could dilute the milk sample used for the human milk analyser measurement if the amount of milk available for testing was insufficient.

SUBJECTS AND METHODS

First, the results of protein, fat and lactose content in breast milk samples obtained using the human milk analyser and conventional methods were compared. Second, we measured diluted samples and compared the values with nondiluted samples.

RESULTS

When comparing the human milk analyser and conventional methods, all three nutrients exhibited a significantly positive correlation (p < 0.001); lactose content was reliable on the condition that it is 6-7 g/dL. The lactose content measured by the HPLC method was obtained by 3.05 x human milk analyser value - 13.4. When comparing diluted and nondiluted samples, fat and protein had expected values after dilution whereas lactose did not.

CONCLUSION

The human milk analyser can inform us about the amount of major nutrients in breast milk: fat, protein and lactose. However, when human milk is diluted, the lactose content measured by the human milk analyser is overestimated.

Preventing postnatal growth failure--the significance of feeding when the preterm infant is clinically stable

Nutrition guidelines and growth targets for preterm infants are currently based upon the reference standard of intrauterine growth and fetal nutrient accretion rates. This may not be an entirely appropriate standard--it is rarely achieved in clinical practice. Postnatal growth failure of very preterm infants is a universal problem with potentially significant, adverse neurological and health outcomes. The nutrient deficit that accumulates in the early weeks postdelivery when the preterm infant is clinically unstable is difficult to recover. Weight, length and head circumference measurements remain important clinical indicators of growth but composition of weight gain is emerging as a necessary measure in determining the adequacy of nutrition intake and growth. Recommended protein and energy intakes for very preterm infants are difficult to achieve with commercial human milk fortifiers and during hospitalisation, targeting the fortification of human milk to optimise the protein to energy ratio of milk feeds is necessary to ensure appropriate composition of weight gain. Postdischarge, continued fortification of human milk feeds may be required for a limited period of time for preterm infants with suboptimal weight for corrected age.

AIM AND METHODS

The following systematic review is aimed to derive evidence-based best practice guidelines for prevention of postnatal growth failure of very preterm infants who are clinically stable and growing. The focus is on reviewing the standard upon which ideal growth and nutrition guidelines are based and targeting fortification to maximise the protein to energy ratio in human milk feeds to ensure appropriate composition of weight gain. Directions for future research are provided. For the literature review the data bases Medline, EMBASE, CINAHL, the Cochrane Library and reference lists of review articles were reviewed to December 2006. A hand search of paediatric and perinatal journals was also conducted.

Pre- and post-discharge feeding of very preterm infants: impact on growth and bone mineralization

In this prospective study we examined (1) how the nutritional status of very preterm infants, judged by growth measures and biochemical values, evolved during the initial hospitalization; (2) the effect of feeding on growth after discharge from hospital; and (3) the risk factors associated with low lumbar bone mineral content (BMC) later in infancy. Sixty-four former preterm infants had their lumbar spine (L2-L4) BMC assessed by dual energy X-ray absorptiometry when they weighed between 5 and 7 kg. Predicted BMC values were calculated based on our previously reported reference lumbar BMC data. These values were used to convert the preterm infants' BMC values into percentages. The extremely preterm group (gestational age < or =28 weeks) had significantly more respiratory morbidity and longer duration of hospital stay than the more mature infants. Both groups developed growth retardation and malnutrition during the hospital stay. Exclusive breastfeeding after discharge from hospital supported linear catch-up growth and weight gain but was associated with a 7.0 (1.2-41.7)-fold risk of having low BMC values. The other factors associated with the risk of having low BMC values later in infancy were low serum phosphate levels at 6 weeks, with a 7.8 (1.6-37.0)-fold risk, and male gender, with a 4.3 (1.2-16.1)-fold risk. Appropriately designed interventional studies are needed to improve the growth and nutrition of these infants during initial hospitalization. In order to improve the postdischarge nutrition, we suggest that the amount and duration of multicomponent human milk fortification should be studied further to provide individualized nutrition throughout the catch-up growth period until the end of the first year of life.

What every nurse needs to know about breast pumping: instructing and supporting mothers of premature infants in the NICU

Research has established that breast milk is the best source of nutrition for the premature infant. Because the infant is born prematurely, the mother will need support in expressing breast milk for her infant's use. The clinical nurse has the opportunity to educate the mother on the importance of breast milk for the premature infant and to support the mother through the course of pumping. However, many nurses are not sufficiently educated in the physiology of lactation to adequately support the mother. The purpose of this article is to educate the bedside nurse in the physiology of lactation so that the mother is adequately assisted in expressing breast milk for her vulnerable infant.

Clinical and economic outcomes of infants receiving breast milk in the NICU

ISSUES AND PURPOSE

This study compared clinical and economic outcomes for infants who were exclusively fed breast milk and infants who were fed commercial formula.

DESIGN AND METHODS

A retrospective medical record review from a regional neonatal intensive care unit (N = 80) using consultation logs from the lactation coordinator and a matched sample of formula-fed infants.

RESULTS

Neither clinical (weight gain, length of stay, days of parenteral nutrition) nor economic outcomes (direct variable costs, net revenue) differed significantly between the groups.

PRACTICE IMPLICATIONS

While it may not be possible to demonstrate sufficient cost savings while the infant resides within the NICU to justify a lactation coordinator, long-term clinical and economic outcomes may be sensitive to this specialized nursing service.

Nipple shields for preterm infants: effect on milk transfer and duration of breastfeeding

This study reports breastfeeding outcomes for 34 preterm infants whose mothers used ultrathin silicone nipple shields to increase milk transfer. Mean milk transfer was compared for 2 consecutive breastfeedings without and with the nipple shield. Total duration of breastfeeding was calculated for a maximum of 365 days. Mean milk transfer was significantly greater for feedings with the nipple shield (18.4 ml vs. 3.9 ml), with all 34 infants consuming more milk with the nipple shield in place. Mean duration of nipple shield use was 32.5 days, and mean duration of breastfeeding was 169.4 days; no association between these variables was noted. The nipple shield was used for 24.3% of the total breastfeeding experience, with no significant association between the percentage of time the shield was used and total duration of breastfeeding. These findings are the first to indicate that nipple shield use increases milk intake without decreasing total duration of breastfeeding for preterm infants.

Utilization of docosahexaenoic acid from intravenous egg yolk phospholipid

Docosahexaenoic acid (DHA, 22:6n-3) is provided directly to human premature infants during parenteral nutrition from the egg yolk fraction of an intravenous fat emulsion. This study aimed to determine whether the high egg yolk phospholipid content of Intralipid 10% (IL 10%, Pharmacia, Uppsala, Sweden) relative to the standard emulsion Intralipid 20% (IL 20%, Pharmacia) could be a strategy to increase the delivery of DHA to the developing brain. Male, Large White piglets were randomly selected from sows 3 d after birth. Piglets were assigned to receive a 9-d continuous intravenous infusion commencing 5 d after birth of either Intralipid (IL) 10%, IL 20%, or Lipofundin S 20% (LFS; B. Braun, Melsungen, Germany). There were four piglets in each treatment group. IL 10% provides twice as much DHA as IL 20%, while LFS provides no DHA. Protein and other nutrients were provided enterally using a low-fat milk formula. After 9 d, animals were killed, and the fatty acid compositions of blood, liver, and cerebral cortex were analyzed. IL 10% infusion approximately doubled the amount of plasma phospholipid DHA (microg/mL of plasma) in comparison to IL 20%. However, red blood cells, liver, and cerebral cortex phospholipid DHA levels were indistinguishable between these two groups. LFS was associated with reduced levels of DHA in plasma, red blood cell and liver phospholipids in comparison to IL 20%. We conclude that infusion of additional phospholipid is an ineffective strategy for increasing DHA delivery to piglet tissues. This may be due to the formation of inert phospholipid particles in plasma. The data do not support the concept of using IL 10% as a means of providing additional DHA to premature human infants.

Neonatology for the generalist: human milk banks and evidence-based medicine

Human milk (HM) banks provide pasteurised milk from screened donors for infants in many countries but not in Australia. There are potential benefits and risks from feeding donor milk with the benefits most likely for preterm infants. A randomized clinical trial is required to provide conclusive evidence. Promotion of breast-feeding with the establishment of HM banks may prove to be an important primary health care activities for infants in Australia.

Characterization of fatty acid clearance in premature neonates during intralipid infusion

This study reports the clearance of plasma triglyceride and phospholipid fatty acids during Intralipid 20% infusion (Pharmacia, Sweden) in nine ventilated preterm infants receiving parenteral nutrition. Blood samples were taken during lipid infusion and over a subsequent period of 36 h of fat-free parenteral nutrition. Plasma triglyceride fatty acids showed a uniform and rapid decline after lipid was stopped from the peak values recorded during infusion. In contrast, plasma phospholipid fatty acids showed a variable decline during fat-free nutrition. This variability appeared to be the result of a differing contribution of infused egg yolk phospholipid fatty acids to the measured plasma values, and to changing fatty acid composition of endogenous phospholipid in response to fat free nutrition. Red cell phospholipid fatty acid composition was stable over the 36-h clearance study period. These results indicate the complexity of interpretation of plasma fatty acids during lipid infusion. We conclude that red cell phospholipid fatty acids provide the only stable measure of tissue fatty acid composition in parenterally fed preterm infants.