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When is birthweight at term abnormally low? A systematic review and meta-analysis of the association and predictive ability of current birthweight standards for neonatal outcomes.

ABSTRACT: Intrauterine growth restriction is a cause of neonatal morbidity and mortality. A variety of definitions of low birthweight are used in clinical practice, with a lack of consensus regarding which definitions best predict adverse outcomes.To evaluate the relationship between birthweight standards and neonatal outcome in term-born infants (at ≥ 37 weeks of gestation).MEDLINE (1966-January 2011), EMBASE (1980-January 2011), and the Cochrane Library (2011:1) and MEDION were included in our search.Studies comprising live term-born infants (gestation ≥ 37 completed weeks), with weight or other anthropometric measurements recorded at birth along with neonatal outcomes.Data were extracted to populate 2 × 2 tables relating birthweight standard with outcome, and meta-analysis was performed where possible.Twenty-nine studies including 21 034 114 neonates were selected. Absolute birthweight was strongly associated with mortality, with birthweight < 1.5 kg giving the largest association (OR 48.6, 95% CI 28.62-82.53). When using centile charts, regardless of threshold, the summary odds ratios were significant but closer to 1 than when using absolute birthweight. For all tests, summary predictive ability comprised high specificity and positive likelihood ratio for neonatal death, but low sensitivity and a negative likelihood ratio close to 1.Absolute birthweight is a prognostic factor for neonatal mortality. The indirect evidence suggests that centile charts or other definitions of low birthweight are not as strongly associated with mortality as the absolute birthweight. Further research is required to improve predictive accuracy.

SUBMITTER: Malin GL

PROVIDER: S-EPMC4162997 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundThe use of birthweight standards to define small for gestational age may fail to identify neonates affected by poor fetal growth as they include births associated with suboptimal fetal growth.ObjectiveThis study aimed to compare intrauterine vs birthweight-derived standards to define newborn small for gestational age to predict neonatal morbidity and mortality.Study designThis was a secondary analysis of a multicenter observational study of 118,422 births. Live-born singleton, nonanomalous newborns born at 23 to 41 weeks of gestation were included. Those with missing gestational age estimation or without a first- or second-trimester ultrasound to confirm dating, birthweight, or neonatal outcome data were excluded. Birthweight percentile was computed using an intrauterine standard (Hadlock) and a birthweight-derived standard (Olsen). We compared the test characteristics of small for gestational age (birthweight of <10th percentile) by each standard to predict a composite neonatal morbidity and mortality outcome (death before discharge, neonatal intensive care unit admission >48 hours, respiratory distress syndrome, sepsis, necrotizing enterocolitis, grade 3 or 4 intraventricular hemorrhage, or seizures). Severe composite morbidity was analyzed as a secondary outcome and was defined as death, neonatal intensive care unit admission >7 days, necrotizing enterocolitis, grade 3 or 4 intraventricular hemorrhage, or seizures. The areas under the curve using receiver-operating characteristic methodology and proportions of the primary outcome by small for gestational age status were compared by gestational age category at birth (<34, 34 0/7 to 36 6/7, ≥37 weeks).ResultsOf 115,502 mother-newborn dyads in the parent study, 78,203 (67.7%) were included, with most exclusions occurring because of missing or inadequate dating information, multiple gestations, or delivery outside the gestational age range. The primary composite outcome occurred in 9.5% (95% confidence interval, 9.3-9.7), and the severe composite outcome occurred in 5.3% (95% confidence interval, 5.1-5.4). Small for gestational age was diagnosed by intrauterine and birthweight-derived standards in 14.8% and 7.4%, respectively (P<.001). Neonates considered small for gestational age only by the intrauterine standard experienced the primary outcome more than twice as often as those considered non-small for gestational age by both standards (18.4% vs 7.9%; P<.001). For the prediction of the primary outcome, small for gestational age by the intrauterine standard had higher sensitivity (29% vs 15%; P<.001) but lower specificity (87% vs 93%; P<.001) than by the birthweight standard. Both standards had weak performance overall, although the intrauterine standard had a higher area under the curve (0.58 vs 0.53; P<.001). When subanalyzed by gestational age at birth, the difference in areas under the curve was only present among preterm deliveries 34 to 36 competed weeks. Neither standard demonstrated any discrimination for morbidity prediction among term births (area under the curve, 0.50 for both). When the prediction of severe morbidity was compared, the intrauterine still had better overall prediction than the birthweight standard (areas under the curve, 0.65 vs 0.57; P<.001), although this also varied by gestational age at birth.ConclusionAmong nonanomalous neonates, neither intrauterine nor birthweight-derived standards for small for gestational age accurately predicted neonatal morbidity and mortality, with no discriminatory ability at term. Small for gestational age intrauterine standards performed better than birthweight standards.

Project description:Background: Neonatal infection is the third largest cause of death in children under five worldwide. Nutritional immunity is the process by which the host innate immune system limits nutrient availability to invading organisms. Iron is an essential micronutrient for both microbial pathogens and their mammalian hosts. Changes in iron availability and distribution have significant effects on pathogen virulence and on the immune response to infection. Our previously published data shows that, during the first 24 hours of life, full-term neonates have reduced overall serum iron. Transferrin saturation decreases rapidly from 45% in cord blood to ~20% by six hours post-delivery. Methods: To study neonatal nutritional immunity and its role in neonatal susceptibility to infection, we will conduct an observational study on 300 full-term normal birth weight (FTB+NBW), 50 preterm normal birth weight (PTB+NBW), 50 preterm low birth weight (PTB+LBW) and 50 full-term low birth weight (FTB+LBW), vaginally-delivered neonates born at Kanifing General Hospital, The Gambia. We will characterize and quantify iron-related nutritional immunity during the early neonatal period and use ex vivo sentinel bacterial growth assays to assess how differences in serum iron affect bacterial growth. Blood samples will be collected from the umbilical cord (arterial and venous) and at serial time points from the neonates over the first week of life. Discussion: Currently, little is known about nutritional immunity in neonates. In this study, we will increase understanding of how nutritional immunity may protect neonates from infection during the first critical days of life by limiting the pathogenicity and virulence of neonatal sepsis causing organisms by reducing the availability of iron. Additionally, we will investigate the hypothesis that this protective mechanism may not be activated in preterm and low birth weight neonates, potentially putting these babies at an enhanced risk of neonatal infection. Trial registration: clinicaltrials.gov ( NCT03353051) 27/11/2017.

Project description:BackgroundResearch investigating the wellbeing of term neonates in the United States is scarce. The objectives of this study were to estimate the prevalence of low birthweight (LBW) and neonatal intensive care unit (NICU) admission among term singletons in association with maternal smoking intensity exposure status, to explore LBW as a mediator linking smoking to immediate newborn NICU transfer/admission, and to assess the potential impact of unmeasured confounding in effect estimates.MethodsThe Natality File of live births registered in the United States in 2016, the first year that all 50 states implemented the revised 2003 standard birth certificate, was restricted to singleton term births (37-41 completed weeks gestation). The prevalence of LBW (< 2500 g) and NICU transfer/admission was estimated across maternal demographic characteristics and smoking intensity status in early and in late pregnancy. Mediation analyses, based on the counterfactual approach, were conducted to examine the total effect (TE), controlled direct effect (CDE), natural direct (NDE) and indirect effects (NIE), and the percentage mediated through LBW. The E-values based on effect size estimates and on lower-bounds of 95% confidence intervals (CIs) assessed the potential impact of unmeasured confounding.ResultsNearly 6.8% of women smoked in early and in late pregnancy, most (36.4%) smoked at high intensity (≥ 10 cigarettes /day) and had the highest prevalence of LBW (6.7%) and NICU transfer/admission (7.0%). For the largest smoking intensity exposure category, the estimate of the TE was 1.68 (95% CI: 1.63, 1.73), of the NDE was 1.56 (95% CI: 1.51, 1.61), of the NIE was 1.08 (95% CI:1.07, 1.09), and the percentage mediated by LBW was 17.6%. The E-values for association estimates and for the lower-bounds of 95% CIs demonstrated the minimum strength of the potential unmeasured confounding necessary to explain away observed associations.ConclusionsThese findings fill a gap on the prevalence of LBW and NICU transfer/admission in term neonates of mothers who smoke and on the role of LBW linking to NICU placement, which could be used to update practitioners, to implement smoking cessation interventions, monitor trends, and to inform planning and allocation of healthcare resources.

Project description:Background and objectiveVery low birthweight (VLBW) infants are highly susceptible to respiratory infections. Information about prevalence of viral respiratory infections (VRIs) in neonatal intensive care unit (NICU) is scarce. Recent evidence suggests short-term and long-term impact of VRI in morbidity of VLBW infants. The goal of this study is to conduct a VRI surveillance in VLBW infants during NICU admission to address the prevalence, type of viruses and associated clinical features.MethodsProspective observational cohort study on infants below 32 gestational weeks admitted to a tertiary NICU during a 2-year period. Respiratory virus detection (influenza, parainfluenza, rhinovirus (hRV), enterovirus, respiratory syncytial virus, metapneumovirus, coronavirus, bocavirus and adenovirus) was performed by real time multiplex PCR assays in nasopharyngeal aspirates (NPAs), within the first 72 hours after birth and weekly, until discharge. Additional samples were taken if clinically indicated.Results147 out of 224 eligible infants were enrolled. At least one positive NPA was found in 38% of the study cohort. Main viruses identified were hRV (58%) and adenovirus (31%). Among the 56 infants with positive NPA, 26 showed non-specific respiratory features in 58% (increased respiratory workload, tachypnoea, apnoea) or typical cold features in 38% (rhinorrhea, cough, fever), at least in one episode. Antibiotics were prescribed in 29% of cases. Positive infants showed higher rates of bronchopulmonary dysplasia (BPD), need for supplemental oxygen and mechanical ventilation, and had longer hospital stay. Cox regression analysis found BPD as an independent risk factor for viral infection (p<0.001) and symptomatic VRI (p<0.04).ConclusionsSystematic surveillance in VLBW infants reports VRI is frequent, particularly by hRV. Asymptomatic infection is highly prevalent which is critical in the face of establishing appropriate preventive strategies. Infants with BPD are especially vulnerable to such infections.

Project description:BackgroundWell-designed clinical studies on the palatal development in preterm and low birthweight infants are desirable because the literature is characterized by contradictory results. It could be shown that knowledge about 'normal' palatal development is still weak as well (Part 1). The objective of this review is therefore to contribute a fundamental analysis of methodologies, confounding factors, and outcomes of studies on palatal development in preterm and low birthweight infants.MethodsAn electronic literature search as well as hand searches were performed based on Cochrane search strategies including sources of more than a century in English, German, and French. Original data were recalculated from studies which primarily dealt with both preterm and term infants. The extracted data, especially those from non-English paper sources, were provided unfiltered for comparison.ResultsSeventy-eight out of 155 included articles were analyzed for palatal morphology of preterm infants. Intubation, feeding tubes, feeding mode, tube characteristics, restriction of oral functions, kind of diet, cranial form and birthweight were seen as causes contributing to altered palatal morphology. Changes associated with intubation concern length, depth, width, asymmetry, crossbite, and contour of the palate. The phenomenon 'grooving' has also been described as a complication associated with oral intubation. However, this phenomenon suffers from lack of a clear-cut definition. Head flattening, pressure from the oral tube, pathologic or impaired tongue function, and broadening of the alveolar ridges adjacent to the tube have been raised as causes of 'grooving'. Metrically, the palates of intubated preterm infants remain narrower, which has been examined up to the age of the late mixed dentition.ConclusionThere is no evidence that would justify the exclusion of any of the raised causes contributing to palatal alteration. Thus, early orthodontic and logopedic control of formerly orally intubated preterm infants is recommended, as opposed to non-intubated infants. From the orthodontic point of view, nasal intubation should be favored. The role that palatal protection plates and pressure-dispersing pads for the head have in palatal development remains unclear.

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When is birthweight at term abnormally low? A systematic review and meta-analysis of the association and predictive ability of current birthweight standards for neonatal outcomes.

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