Association between maternal omega-3 polyunsaturated fatty acids supplementation and preterm delivery: A proteomic study.

Maternal nutrition during pregnancy influences offspring health. Dietary supplementation of pregnant women with (n-3) long-chain polyunsaturated fatty acids (PUFA) was shown to exert beneficial effects on offspring, through yet unknown mechanisms. Here, we conducted a dietary intervention study on a cohort of 10 women diagnosed with threatened preterm labor with a nutritional integration with eicosapentaenoic and docosahexaenoic acids. Microvesicles (MV) isolated form arterial cord blood of the treated cohort offspring and also of a randomized selection of 10 untreated preterm and 12 term newborns, were characterized by dynamic light scattering and analyzed by proteomic and statistical analysis. Glutathione synthetase was the protein bearing the highest discrimination ability between cohorts. ELISA assay showed that glutathione synthetase was more abundant in cord blood from untreated preterm compared to the other conditions. Assay of free SH-groups showed that serum of preterm subjects was oxidized. Data suggest that preterm suffer from oxidative stress, which was lower in the treated cohort. This study confirms that MV are a representative sample of the individual status and the efficacy of dietary intervention with PUFA in human pregnancy in terms of lowered inflammatory status, increased gestational age and weight at birth.

Maternal dietary selenium intake is associated with increased gestational length and decreased risk of preterm delivery.

The first positive genome-wide association study on gestational length and preterm delivery showed the involvement of an Se metabolism gene. In the present study, we examine the association between maternal intake of Se and Se status with gestational length and preterm delivery in 72 025 women with singleton live births from the population-based, prospective Norwegian Mother, Father and Child Cohort Study (MoBa). A self-reported, semi-quantitative FFQ answered in pregnancy week 22 was used to estimate Se intake during the first half of pregnancy. Associations were analysed with adjusted linear and Cox regressions. Se status was assessed in whole blood collected in gestational week 17 (n 2637). Median dietary Se intake was 53 (interquartile range (IQR) 44-62) µg/d, supplements provided additionally 50 (IQR 30-75) µg/d for supplement users (n 23 409). Maternal dietary Se intake was significantly associated with prolonged gestational length (ß per sd = 0·25, 95 % CI, 0·07, 0·43) and decreased risk of preterm delivery (n 3618, hazard ratio per sd = 0·92, 95 % CI, 0·87, 0·98). Neither Se intake from supplements nor maternal blood Se status was associated with gestational length or preterm delivery. Hence, the present study showed that maternal dietary Se intake but not intake of Se-containing supplements, during the first half of pregnancy was significantly associated with decreased risk of preterm delivery. Further investigations, preferably in the form of a large randomised controlled trial, are needed to elucidate the impact of Se on pregnancy duration.

Omega-3 fatty acid supplementation in pregnancy-baseline omega-3 status and early preterm birth: exploratory analysis of a randomised controlled trial.

OBJECTIVE: To identify a polyunsaturated fatty acid (PUFA) biomarker able to detect which women with singleton pregnancies are most likely to benefit from omega-3 supplementation to reduce their risk of early preterm birth. DESIGN: Exploratory analysis of a randomised controlled trial. SETTING: Six Australian hospitals. POPULATION: Women with a singleton pregnancy enrolled in the ORIP trial. METHODS: Using maternal capillary whole blood collected ~14 weeks' gestation, the fatty acids in total blood lipids were quantified using gas chromatography. Interaction tests examined whether baseline PUFA status modified the effect of omega-3 supplementation on birth outcomes. MAIN OUTCOME MEASURE: Early preterm birth (<34 weeks' gestation). RESULTS: A low total omega-3 PUFA status in early pregnancy was associated with a higher risk of early preterm birth. Among women with a total omega-3 status ≤4.1% of total fatty acids, omega-3 supplementation substantially reduced the risk of early preterm birth compared with control (0.73 versus 3.16%; relative risk = 0.23, 95% confidence interval [CI] 0.07-0.79). Conversely, women with higher total omega-3 status in early pregnancy were at lower risk of early preterm birth. Supplementing women with a baseline status above 4.9% increased early preterm birth (2.20 versus 0.97%; relative risk = 2.27, 95% CI 1.13-4.58). CONCLUSIONS: Women with singleton pregnancies and low total omega-3 PUFA status early in pregnancy have an increased risk of early preterm birth and are most likely to benefit from omega-3 supplementation to reduce this risk. Women with higher total omega-3 status are at lower risk and additional omega-3 supplementation may increase their risk. TWEETABLE ABSTRACT: Low total omega-3 fat status helps identify which women benefit from extra omega-3 to reduce early prematurity.

Room for improvement in breast milk feeding after very preterm birth in Europe: Results from the EPICE cohort.

Breast milk feeding (BMF) is associated with lower neonatal morbidity in the very preterm infant (<32 weeks gestation) and breastfeeding is beneficial for maternal health. Previous studies show large variations in BMF after very preterm birth and recognize the need for targeted breastfeeding support in the neonatal intensive care units (NICU). In a European collaboration project about evidence-based practices after very preterm birth, we examined the association between maternal, obstetric, and infant clinical factors; neonatal and maternal care unit policies; and BMF at discharge from the NICU. In multivariable analyses, covariates associated with feeding at discharge were first investigated as predictors of any BMF and in further analysis as predictors of exclusive or partial BMF. Overall, 58% (3,826/6,592) of the infants received any BMF at discharge, but there were large variations between regions (range 36-80%). Primiparity, administration of antenatal corticosteroids, first enteral feed <24 hr after birth, and mother's own milk at first enteral feed were predictors positively associated with any BMF at discharge. Vaginal delivery, singleton birth, and receiving mother's own milk at first enteral feed were associated with exclusive BMF at discharge. Units with a Baby Friendly Hospital accreditation improved any BMF at discharge; units with protocols for BMF and units using donor milk had higher rates of exclusive BMF at discharge. This study suggests that there is a high potential for improving BMF through policies and support in the NICU.

Modeling the Impact of Nutrition Interventions on Birth Outcomes in the Lives Saved Tool (LiST).

Background: Negative birth outcomes [small-for-gestational age (SGA) and preterm birth (PTB)] are common in low- and middle-income countries and have important subsequent health and developmental impacts on children. There are numerous nutritional and non-nutritional interventions that can decrease the risk of negative birth outcomes and reduce subsequent risk of mortality and growth faltering.Objective: The objective of this article was to review the current evidence for the impact of nutritional interventions in pregnancy [calcium supplementation, iron and folic acid supplementation, multiple micronutrient (MMN) supplementation, and balanced energy supplementation (BES)] and risk factors (maternal anemia) on birth outcomes, with the specific goal of determining which intervention-outcome linkages should be included in the Lives Saved Tool (LiST) software.Methods: A literature search was conducted by using the WHO e-Library of Evidence for Nutrition Actions as the starting point. Recent studies, meta-analyses, and systematic reviews were reviewed for inclusion on the basis of their relevance to LiST.Results: On the basis of the available scientific evidence, the following linkages were found to be supported for inclusion in LiST: calcium supplementation on PTB (12% reduction), MMN supplementation on SGA (9% reduction), and BES on SGA (21% reduction among food-insecure women).Conclusions: The inclusion of these linkages in LiST will improve the utility of the model for users who seek to estimate the impact of antenatal nutrition interventions on birth outcomes. Scaling up these interventions should lead to downstream impacts in reducing stunting and child mortality.

Antenatal micronutrient supplementation and third trimester cortisol and erythropoietin concentrations.

Antenatal iron and multiple micronutrient supplementation has been shown in randomized trials to improve birthweight, although mechanisms are unknown. We examined late pregnancy serum erythropoietin (EPO) and cortisol concentrations in relation to maternal micronutrient supplementation and iron status indicators (haemoglobin, serum ferritin, soluble transferrin receptor) in 737 rural Nepalese women to explore evidence of stress or anaemia-associated hypoxia. A double-masked randomized control trial was conducted from December 1998 to April 2001 in Sarlahi, Nepal, in which women received vitamin A alone (as control), or with folic acid (FA), FA + iron, FA + iron + zinc and a multiple micronutrient supplement. In a substudy, we collected maternal blood in the first and third trimester for biochemical assessments. Generalized estimating equations linear regression analysis was used to examine treatment group differences. EPO was ∼ 14-17 mIU mL(-1) lower (P < 0.0001) in late pregnancy in groups receiving iron vs. the control group, with no difference in the FA-only group. Cortisol was 1.3 µg dL(-1) lower (P = 0.04) only in the micronutrient supplement group compared with the control group. EPO was most strongly associated with iron status indicators in groups that did not receive iron, and in the non-iron groups cortisol was positively correlated with EPO (r = 0.15, P < 0.01) and soluble transferrin receptor (sTfR, r = 0.19, P < 0.001). In adjusted analyses, third trimester EPO was associated with a reduction in low birthweight, whereas cortisol was negatively associated with length of gestation and higher risk of preterm birth. Iron and multiple micronutrient supplementation may enhance birth outcomes by reducing mediators of maternal stress and impaired erythropoiesis.

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.

Effect of a Mediterranean diet during pregnancy on fetal growth and preterm delivery: results from a French Caribbean Mother-Child Cohort Study (TIMOUN).

BACKGROUND: Recent studies suggest that a Mediterranean dietary pattern during pregnancy may influence pregnancy outcomes. The aim of this study was to evaluate the effect of adherence to a Mediterranean diet (MD) during pregnancy on fetal growth restriction (FGR) and preterm delivery (PTD) in a French Caribbean island where the population is largely of African descent and presents dietary patterns similar to MD. METHODS: Using data from the TIMOUN Mother-Child Cohort Study conducted in Guadeloupe (French West Indies) between 2004 and 2007, we analysed data for 728 pregnant women who delivered liveborn singletons without any major congenital malformations. Degree of adherence to MD during pregnancy was evaluated with a semi-quantitative food frequency questionnaire based on nine dietary criteria. Multiple logistic regression models were used to analyse birth outcomes while taking potential confounders into account. RESULTS: Overall there was no association between MD adherence during pregnancy and the risk of PTD or FGR. However, pre-pregnancy body mass index was a strong effect modifier, and MD adherence was associated with a decreased risk of PTD specifically in overweight and obese women (adjusted odds ratio 0.7, 95% confidence interval 0.6, 0.9) (P heterogeneity <0.01). CONCLUSIONS: These results suggest that Caribbean diet during pregnancy may carry some benefits of MD and may contribute to reduce the risk of PTD in overweight and obese pregnant women.

Oral cholecalciferol supplementation alleviates lipopolysaccharide-induced preterm delivery partially through regulating placental steroid hormones and prostaglandins in mice.

Several epidemiological reports demonstrated that vitamin D deficiency elevated risk of preterm delivery. We investigate the effects of oral cholecalciferol (VD3) supplementation on lipopolysaccharide (LPS)-induced preterm delivery. Pregnant mice were randomly assigned to either oral VD3 (25 µg/kg) or corn oil once daily from gestational day (GD)13 to GD15, and were intraperitoneally injected with either LPS (200 µg/kg) or normal saline on GD15. As expected, LPS was effective in inducing preterm delivery and fetal death. LPS-induced preterm delivery and fetal death were alleviated in VD3-pretreated mice. LPS-induced down-regulation of genes for placental progesterone biosynthetic enzymes was blocked in VD3-pretreated mice. LPS-induced reduction of serum progesterone was correspondingly attenuated by VD3. Although oral VD3 had no effect on estradiol production, it attenuated LPS-induced up-regulation of placental ERß in mice. LPS-induced placental COX-2 up-regulation and serum PGF2α elevation were alleviated in VD3-pretreated mice. Additionally, LPS-evoked elevations of the placental Tnfα, Il1ß, Mcp1 and Mip2 mRNAs were attenuated by VD3. VD3 promoted placental vitamin D receptor nuclear translocation and simultaneously alleviated LPS-induced nuclear translocation of NF-κB p65 and p50 subunits. These results provide evidence that oral VD3 supplementation alleviates LPS-induced preterm delivery and fetal demise partially through regulating placental steroid hormones and prostaglandins.

A Systematic Review and Meta-Analysis of Human Milk Feeding and Morbidity in Very Low Birth Weight Infants.

This systematic review and meta-analysis synthesised the post-1990 literature examining the effect of human milk on morbidity, specifically necrotising enterocolitis (NEC), late onset sepsis (LOS), retinopathy of prematurity (ROP), bronchopulmonary dysplasia (BPD) and neurodevelopment in infants born ≤28 weeks' gestation and/or publications with reported infant mean birth weight of ≤1500 g. Online databases including Medline, PubMed, CINAHL, Scopus, and the Cochrane Central Register of Controlled Trials were searched, and comparisons were grouped as follows: exclusive human milk (EHM) versus exclusive preterm formula (EPTF), any human milk (HM) versus EPTF, higher versus lower dose HM, and unpasteurised versus pasteurised HM. Experimental and observational studies were pooled separately in meta-analyses. Risk of bias was assessed for each individual study and the GRADE system used to judge the certainty of the findings. Forty-nine studies (with 56 reports) were included, of which 44 could be included in meta-analyses. HM provided a clear protective effect against NEC, with an approximate 4% reduction in incidence. HM also provided a possible reduction in LOS, severe ROP and severe NEC. Particularly for NEC, any volume of HM is better than EPTF, and the higher the dose the greater the protection. Evidence regarding pasteurisation is inconclusive, but it appears to have no effect on some outcomes. Improving the intake of mother's own milk (MOM) and/or donor HM results in small improvements in morbidity in this population.

Different concentrations of docosahexanoic acid supplement during lactation result in different outcomes in preterm Sprague-Dawley rats.

PROPOSE: In this study, we evaluated the effects of different concentrations of docosahexanoic acid (DHA) supplement on preterm Sprague-Dawley rat pups, and in parallel, measured the phosphorylation activity of the mTOR pathway in the hippocampal CA1 area. METHODS: Preterm Sprague-Dawley rat pups were randomly assigned to experimental groups which included; a sufficient DHA group (100 mg/kg/day); an enriched DHA group (300 mg/kg/day); an excess DHA group (800 mg/kg/day); and a deficient DHA group (normal saline gavage 0.1 ml/10 g). Body weight (g) was measured at days 1/7/14/21/28/42, respectively. Spatial learning and memory were also tested using the Morris water maze at week 6 (day 42). Finally, activation of the mTOR signaling pathway in hippocampal CA1 area were evaluated by western blotting. RESULTS: Postnatal sufficient/enriched docosahexanoic acid supplement ameliorated body weight restriction, spatial learning and memory restriction, and decreased phosphorylation of AKT, mTOR, P70S6K1, and 4EBP1 in hippocampal CA1 area. Furthermore, excess docosahexanoic acid supplement impeded weight gain and spatial learning and memory, perturbed serum unsaturated fatty acid, and downregulated phosphorylation of AKT, mTOR, P70S6K1, and 4EBP1 in hippocampal CA1 area. CONCLUSION: Postnatal sufficient/enriched DHA supplement ameliorated growth and spatial learning and memory impairment and upregulated the mTOR pathway in preterm pups, although excessive DHA supplement did not have any beneficial effects.

The influence of probiotics for preterm neonates on the incidence of atopic dermatitis-results from a historically controlled cohort study.

Probiotic supplementation is a promising preventive strategy for atopic dermatitis (AD). To help clarifying the significance of timing with respect to prevention of AD, we here evaluate the benefit of prophylactic use of probiotic supplementation in neonates younger than 30 weeks of gestation. Preterm children from the Department of Neonatology, Rigshospitalet, Denmark from two different admission periods were included in a historically controlled cohort study. Neonates from January 2007 to February 2010, not treated with and neonates from March 2010 to February 2013 treated with probiotic were enrolled. Main outcome was prevalence of AD, and secondary outcomes were use of topical corticosteroids, and number of skin-related visits to GPs and dermatologists. 527 preterm neonates were included in the study, 249 treated and 278 not treated with probiotics. Response rate for the two cohorts was 76.7 and 77.7% respectively. The prevalence of AD was similar in the two groups (20.9% in the probiotic treated group versus 17.1% in the not treated group, p = 0.33). No significant differences were found between the groups with respect to treatment with topical corticosteroids, or visits at GPs or dermatologist. We found no indication that probiotics may prevent AD when administered to neonates <30 gestation weeks from birth until discharge home. Factors influencing the early maturation of the immune system have been assumed to be of particular importance in atopic dermatitis, and hence, our unique cohorts contribute information on how probiotic supplementation may affect the extremely immature immune systems of preterm infants.

Monitoring postnatal growth of preterm infants: present and future.

BACKGROUND: There is no consensus with regard to which charts are most suitable for monitoring the postnatal growth of preterm infants. OBJECTIVE: We aimed to assess the strategies used to develop existing postnatal growth charts for preterm infants and their methodologic quality. DESIGN: A systematic review of observational longitudinal studies, having as their primary objective the creation of postnatal growth charts for preterm infants, was conducted. Thirty-eight items distributed in 3 methodologic domains ("study design," "statistical methods," and "reporting methods") were assessed in each study. Each item was scored as a "low" or "high" risk of bias. Two reviewers independently selected the studies, assessed the risk of bias, and extracted data. A total quality score [(number of "low risk" of bias marks/total number of items assessed) × 100%] was calculated for each study. Median (range, IQR) quality scores for each methodologic domain and for all included studies were computed. RESULTS: Sixty-one studies met the inclusion criteria. Twenty-seven (44.3%) of the 61 studies scored ≥50%, of which 10 scored >60% and only 1 scored >66%. The median (range, IQR) quality score for the 61 included studies was 47% (26-75%, 34-56%). The scores for the domains study design, statistical methods, and reporting methods were 44% (19-67%, 33-52%), 25% (0-88%, 13-38%), and 33% (0-100%, 0-33%), respectively. The most common shortcomings were observed in items related to anthropometric measures (the main variable of interest), gestational age estimation, follow-up duration, reporting of postnatal care and morbidities, assessment of outliers, covariates, and chart presentation. CONCLUSIONS: The overall methodologic quality of existing longitudinal studies was fair to low. To overcome these problems, the Preterm Postnatal Follow-up Study, 1 of the 3 main components of The International Fetal and Newborn Growth Consortium for the 21st Century Project, was designed to construct preterm postnatal growth standards from a prospective cohort of "healthy" pregnancies and preterm newborns without evidence of fetal growth restriction.

Defining Protein Requirements of Preterm Infants by Using Metabolic Studies in Fetuses and Preterm Infants.

Amino acids form one of the main building blocks for fetal and neonatal growth. Despite improvements in neonatal care, including postnatal nutrition, growth faltering and suboptimal outcome after premature birth are still frequently encountered. Nutrition can partly be held responsible. Over the years, there has been a trend in delivering amino acids earlier from birth on and in larger quantities. Unfortunately, little is known about the specific metabolism of proteins, especially during fetal life or during disease. This review gives an overview of different methods of studying metabolism during early life and what we have come to learn so far. Different examples are given on the complex interplay between the placenta and the fetus. From both ovine and human studies, we know that amino acids are not only used for protein synthesis in the fetus, they are also oxidized to a large extent. Postnatally, we have succeeded in improving the nitrogen balance in preterm infants, but the preconditions need also to be improved before concluding that today's policy is optimal. Only by gaining more knowledge on both fetal and neonatal physiology and disease will we be able to further optimize growth and functional outcome in premature infants.

Development of infant oral feeding skills: what do we know?

The hospital discharge of premature infants in neonatal intensive care units is often delayed due to their inability to feed by mouth safely and competently. With immature physiologic functions, infants born prematurely cannot be expected to readily feed by mouth at the equivalent age of a third trimester of gestation as the majority of their term counterparts do. Consequently, it is crucial that health care professionals gain an adequate knowledge of the development of preterm infants' oral feeding skills so as to optimize their safety and competency as they transition to oral feeding. With a greater sensitivity toward their immature skills, we can offer these infants a safer and smoother transition to independent oral feeding than is currently observed. This review article is an overview of the evidence-based research undertaken over the past 2 decades on the development of very-low-birth-weight infants' oral feeding skills. The description of the different functional levels where these infants can encounter hurdles may assist caregivers in identifying a potential cause or causes for their individual patients' oral feeding difficulties.

Dysphagia in the high-risk infant: potential factors and mechanisms.

Neonatal dysphagia, or abnormalities of swallowing, represent a major global problem, and consequences of dysfunctional feeding patterns carry over into infancy and toddler age groups. Growth, development, and independent feeding skills are all delayed among high-risk infants. Such a group comprises premature birth, low-birth-weight, congenital anomalies, perinatal asphyxia, postsurgical, and sepsis categories. The conflict between pathophysiologic and pragmatic feeding strategies remains a major conundrum and is largely due to a lack of validated diagnostic approaches amid heterogeneity of the patient phenotype. Thus, well-tested feeding management strategies that can be generalizable are lacking. Furthermore, the aerodigestive symptoms and signs, potential risk factors, and contributory etiologies remain nonspecific. This article presents mechanistic evidence related to the pathophysiologic basis of neonatal dysphagia as well as potential opportunities to improve feeding abilities and long-term development.

Working group reports: evaluation of the evidence to support practice guidelines for nutritional care of preterm infants-the Pre-B Project.

The "Evaluation of the Evidence to Support Practice Guidelines for the Nutritional Care of Preterm Infants: The Pre-B Project" is the first phase in a process to present the current state of knowledge and to support the development of evidence-informed guidance for the nutritional care of preterm and high-risk newborn infants. The future systematic reviews that will ultimately provide the underpinning for guideline development will be conducted by the Academy of Nutrition and Dietetics' Evidence Analysis Library (EAL). To accomplish the objectives of this first phase, the Pre-B Project organizers established 4 working groups (WGs) to address the following themes: 1) nutrient specifications for preterm infants, 2) clinical and practical issues in enteral feeding of preterm infants, 3) gastrointestinal and surgical issues, and 4) current standards of infant feeding. Each WG was asked to 1) develop a series of topics relevant to their respective themes, 2) identify questions for which there is sufficient evidence to support a systematic review process conducted by the EAL, and 3) develop a research agenda to address priority gaps in our understanding of the role of nutrition in health and development of preterm/neonatal intensive care unit infants. This article is a summary of the reports from the 4 Pre-B WGs.

Long-chain polyunsaturated fatty acids and the preterm infant: a case study in developmentally sensitive nutrient needs in the United States.

The vast majority of infant formulas in the United States contain the long-chain polyunsaturated fatty acids (PUFAs) docosahexaenoic acid (22:6n-3) and arachidonic acid (20:4n-6), which were first permitted by the US Food and Drug Administration in 2001. As a scientific case study, preclinical animal studies of these nutrients definitively influenced the design and interpretation of human clinical studies. Early studies were tied to the availability of test substances, and in hindsight suggest re-evaluation of the essential fatty acid concept in light of the totality of available evidence. Research in the 1950s established the essentiality of n-6 PUFAs for skin integrity; however, widespread recognition of the essentiality of n-3 PUFAs came decades later despite compelling evidence of their significance. Barriers to an understanding of the essentiality of n-3 PUFAs were as follows: 1) their role is in neural function, which is measured only with difficulty compared with skin lesions and growth faltering that are apparent for n-6 PUFAs; 2) the experimental use of vegetable oils as PUFA sources that contain the inefficiently used C18 PUFAs rather than the operative C20 and C22 PUFAs; 3) the shift from reliance on high-quality animal studies to define mechanisms that established the required nutrients in the first part of the 20th century to inherently challenging human studies. Advances in nutrition of premature infants require the best practices and opinions available, taking into account the totality of preclinical and clinical evidence.

Executive summary: evaluation of the evidence to support practice guidelines for nutritional care of preterm infants-the Pre-B Project.

Preterm birth (infants born at <37 wk of gestational age) is a significant clinical and public health challenge in the United States and globally. No universally accepted practice guidelines exist for the nutritional care of preterm infants. To address the current state of knowledge and to support systematic reviews that will be used to develop evidence-informed guidance, a consortium consisting of the American Academy of Pediatrics, the ASN, the American Society for Parenteral and Enteral Nutrition, the Academy of Nutrition and Dietetics, the Food and Drug Administration, the CDC, the USDA/Agricultural Research Service (USDA/ARS), and the Eunice Kennedy Shriver National Institute of Child Health and Human Development/NIH initiated the Pre-B Project. The project included the constitution of 4 thematic working groups charged with the following tasks: 1) develop a series of topics/questions for which there is sufficient evidence to support a systematic review process to be conducted by the Academy of Nutrition and Dietetics' Evidence Analysis Library (EAL), leading to the development of new guidelines for nutritional care of preterm infants, and 2) develop a targeted research agenda to address priority gaps in our understanding of the role of nutrition in the health and development of preterm/neonatal intensive care unit infants. This review consists of a project overview including a summary of a workshop hosted by the USDA/ARS Children's Nutrition Research Center and summary reports of the 4 working groups established to address the following themes: 1) nutrient specifications, 2) clinical/practical issues in enteral feeding, 3) gastrointestinal and surgical issues, and 4) current standards for assessing infant feeding outcomes. These reports will serve as the basis for the ultimate guideline development process to be conducted by the Academy of Nutrition and Dietetics' EAL.