Exposure to per- and polyfluoroalkyl substances and alterations in plasma microRNA profiles in children.

BACKGROUND: Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals that persist in the environment and can accumulate in humans, leading to adverse health effects. MicroRNAs (miRNAs) are emerging biomarkers that can advance the understanding of the mechanisms of PFAS effects on human health. However, little is known about the associations between PFAS exposures and miRNA alterations in humans. OBJECTIVE: To investigate associations between PFAS concentrations and miRNA levels in children. METHODS: Data from two distinct cohorts were utilized: 176 participants (average age 17.1 years; 75.6% female) from the Teen-Longitudinal Assessment of Bariatric Surgery (Teen-LABS) cohort in the United States, and 64 participants (average age 6.5 years, 39.1% female) from the Rhea study, a mother-child cohort in Greece. PFAS concentrations and miRNA levels were assessed in plasma samples from both studies. Associations between individual PFAS and plasma miRNA levels were examined after adjusting for covariates. Additionally, the cumulative effects of PFAS mixtures were evaluated using an exposure burden score. Ingenuity Pathways Analysis was employed to identify potential disease functions of PFAS-associated miRNAs. RESULTS: Plasma PFAS concentrations were associated with alterations in 475 miRNAs in the Teen-LABs study and 5 miRNAs in the Rhea study (FDR p < 0.1). Specifically, plasma PFAS concentrations were consistently associated with decreased levels of miR-148b-3p and miR-29a-3p in both cohorts. Pathway analysis indicated that PFAS-related miRNAs were linked to numerous chronic disease pathways, including cardiovascular diseases, inflammatory conditions, and carcinogenesis. CONCLUSION: Through miRNA screenings in two independent cohorts, this study identified both known and novel miRNAs associated with PFAS exposure in children. Pathway analysis revealed the involvement of these miRNAs in several cancer and inflammation-related pathways. Further studies are warranted to enhance our understanding of the relationships between PFAS exposure and disease risks, with miRNA emerging as potential biomarkers and/or mediators in these complex pathways.

Associations of Maternal Educational Level, Proximity to Greenspace During Pregnancy, and Gestational Diabetes With Body Mass Index From Infancy to Early Adulthood: A Proof-of-Concept Federated Analysis in 18 Birth Cohorts.

International sharing of cohort data for research is important and challenging. We explored the feasibility of multi-cohort federated analyses by examining associations between three pregnancy exposures (maternal education, exposure to green vegetation and gestational diabetes) with offspring BMI from infancy to 17 years. We used data from 18 cohorts (n=206,180 mother-child pairs) from the EU Child Cohort Network and derived BMI at ages 0-1, 2-3, 4-7, 8-13 and 14-17 years. Associations were estimated using linear regression via one-stage IPD meta-analysis using DataSHIELD. Associations between lower maternal education and higher child BMI emerged from age 4 and increased with age (difference in BMI z-score comparing low with high education age 2-3 years = 0.03 [95% CI 0.00, 0.05], 4-7 years = 0.16 [95% CI 0.14, 0.17], 8-13 years = 0.24 [95% CI 0.22, 0.26]). Gestational diabetes was positively associated with BMI from 8 years (BMI z-score difference = 0.18 [CI 0.12, 0.25]) but not at younger ages; however associations attenuated towards the null when restricted to cohorts which measured GDM via universal screening. Exposure to green vegetation was weakly associated with higher BMI up to age one but not at older ages. Opportunities of cross-cohort federated analyses are discussed.

Cord blood epigenome-wide meta-analysis in six European-based child cohorts identifies signatures linked to rapid weight growth.

BACKGROUND: Rapid postnatal growth may result from exposure in utero or early life to adverse conditions and has been associated with diseases later in life and, in particular, with childhood obesity. DNA methylation, interfacing early-life exposures and subsequent diseases, is a possible mechanism underlying early-life programming. METHODS: Here, a meta-analysis of Illumina HumanMethylation 450K/EPIC-array associations of cord blood DNA methylation at single CpG sites and CpG genomic regions with rapid weight growth at 1 year of age (defined with reference to WHO growth charts) was conducted in six European-based child cohorts (ALSPAC, ENVIRONAGE, Generation XXI, INMA, Piccolipiù, and RHEA, N = 2003). The association of gestational age acceleration (calculated using the Bohlin epigenetic clock) with rapid weight growth was also explored via meta-analysis. Follow-up analyses of identified DNA methylation signals included prediction of rapid weight growth, mediation of the effect of conventional risk factors on rapid weight growth, integration with transcriptomics and metabolomics, association with overweight in childhood (between 4 and 8 years), and comparison with previous findings. RESULTS: Forty-seven CpGs were associated with rapid weight growth at suggestive p-value <1e-05 and, among them, three CpGs (cg14459032, cg25953130 annotated to ARID5B, and cg00049440 annotated to KLF9) passed the genome-wide significance level (p-value <1.25e-07). Sixteen differentially methylated regions (DMRs) were identified as associated with rapid weight growth at false discovery rate (FDR)-adjusted/Siddak p-values < 0.01. Gestational age acceleration was associated with decreasing risk of rapid weight growth (p-value = 9.75e-04). Identified DNA methylation signals slightly increased the prediction of rapid weight growth in addition to conventional risk factors. Among the identified signals, three CpGs partially mediated the effect of gestational age on rapid weight growth. Both CpGs (N=3) and DMRs (N=3) were associated with differential expression of transcripts (N=10 and 7, respectively), including long non-coding RNAs. An AURKC DMR was associated with childhood overweight. We observed enrichment of CpGs previously reported associated with birthweight. CONCLUSIONS: Our findings provide evidence of the association between cord blood DNA methylation and rapid weight growth and suggest links with prenatal exposures and association with childhood obesity providing opportunities for early prevention.

Maternal sleep disturbances during late pregnancy and child neuropsychological and behavioral development in early childhood.

The present study aims to explore the association of maternal sleep disturbances during late pregnancy on child neuropsychological and behavioral development in preschool years. The study included 638 mother-child pairs from the prospective Rhea mother-child cohort in Crete, Greece. Information on antenatal sleep disturbances was collected through a computer-assisted interview. Children's neuropsychological and behavioral development was assessed using the McCarthy Scales of Children's Abilities (MSCA), the Attention-Deficit Hyperactivity Disorder Test (ADHDT), and the Strengths and Difficulties Questionnaire (SDQ). Multivariate analysis showed that maternal sleep duration less than 8 h was associated with reduced scores in the general cognitive scale (ß = -2.28, 95% CI -4.54, -0.02, R2 = 0.417) and memory span (ß = -3.24, 95% CI -5.72, -0.77, R2 = 0.304), while mild-severe daytime sleepiness was associated with reduced scores in the memory scale (ß = -5.42, 95% CI -10.47, -0.37, R2 = 0.304), memory span (ß = -5.44, 95% CI -10.68, -0.21, R2 = 0.304), nd functions of posterior cortex (ß = -5.55, 95% CI -10.40, -0.70, R2 = 0.393) of MSCA. Snoring in late pregnancy was related to higher child hyperactivity scores in SDQ (ß = 1.05, 95% CI 0.16, 1.95, R2 = 0.160). An interaction between child sex and maternal sleep duration in response to ADHD symptoms was also found (p for interaction < 0.05). Stratified analysis revealed increased hyperactivity, inattention, and ADHD total scores for girls of mothers with sleep duration less than 8 h. Maternal sleep disturbances during pregnancy may be associated with impaired child neuropsychological and behavioral development during the preschool years. Early detection and intervention is necessary to reduce sleep disturbances habits in pregnancy and improve child neurodevelopment.

Cord blood metabolites and rapid postnatal growth as multiple mediators in the prenatal propensity to childhood overweight.

BACKGROUND: The mechanisms underlying childhood overweight and obesity are poorly known. Here, we investigated the direct and indirect effects of different prenatal exposures on offspring rapid postnatal growth and overweight in childhood, mediated through cord blood metabolites. Additionally, rapid postnatal growth was considered a potential mediator on childhood overweight, alone and sequentially to each metabolite. METHODS: Within four European birth-cohorts (N = 375 mother-child dyads), information on seven prenatal exposures (maternal education, pre-pregnancy BMI, weight gain and tobacco smoke during pregnancy, age at delivery, parity, and child gestational age), selected as obesogenic according to a-priori knowledge, was collected. Cord blood levels of 31 metabolites, associated with rapid postnatal growth and/or childhood overweight in a previous study, were measured via liquid-chromatography-quadrupole-time-of-flight-mass-spectrometry. Rapid growth at 12 months and childhood overweight (including obesity) between four and eight years were defined with reference to WHO growth charts. Single mediation analysis was performed using the imputation approach and multiple mediation analysis using the extended-imputation approach. RESULTS: Single mediation suggested that the effect of maternal education, pregnancy weight gain, parity, and gestational age on rapid postnatal growth but not on childhood overweight was partly mediated by seven metabolites, including cholestenone, decenoylcarnitine(C10:1), phosphatidylcholine(C34:3), progesterone and three unidentified metabolites; and the effect of gestational age on childhood overweight was mainly mediated by rapid postnatal growth. Multiple mediation suggested that the effect of gestational age on childhood overweight was mainly mediated by rapid postnatal growth and that the mediating role of the metabolites was marginal. CONCLUSION: Our findings provide evidence of the involvement of in utero metabolism in the propensity to rapid postnatal growth and of rapid postnatal growth in the propensity to childhood overweight. We did not find evidence supporting a mediating role of the studied metabolites alone between the studied prenatal exposures and the propensity to childhood overweight.

In Utero Exposure to Mercury Is Associated With Increased Susceptibility to Liver Injury and Inflammation in Childhood.

BACKGROUND AND AIMS: Nonalcoholic fatty liver disease (NAFLD) is the most prevalent cause of liver disease in children. Mercury (Hg), a ubiquitous toxic metal, has been proposed as an environmental factor contributing to toxicant-associated fatty liver disease. APPROACH AND RESULTS: We investigated the effect of prenatal exposure to Hg on childhood liver injury by combining epidemiological results from a multicenter mother-child cohort with complementary in vitro experiments on monocyte cells that are known to play a key role in liver immune homeostasis and NAFLD. We used data from 872 mothers and their children (median age, 8.1 years; interquartile range [IQR], 6.5-8.7) from the European Human Early-Life Exposome cohort. We measured Hg concentration in maternal blood during pregnancy (median, 2.0 µg/L; IQR, 1.1-3.6). We also assessed serum levels of alanine aminotransferase (ALT), a common screening tool for pediatric NAFLD, and plasma concentrations of inflammation-related cytokines in children. We found that prenatal Hg exposure was associated with a phenotype in children that was characterized by elevated ALT (≥22.1 U/L for females and ≥25.8 U/L for males) and increased concentrations of circulating IL-1ß, IL-6, IL-8, and TNF-α. Consistently, inflammatory monocytes exposed in vitro to a physiologically relevant dose of Hg demonstrated significant up-regulation of genes encoding these four cytokines and increased concentrations of IL-8 and TNF-α in the supernatants. CONCLUSIONS: These findings suggest that developmental exposure to Hg can contribute to inflammation and increased NAFLD risk in early life.

Dietary inflammatory index of mothers during pregnancy and Attention Deficit-Hyperactivity Disorder symptoms in the child at preschool age: a prospective investigation in the INMA and RHEA cohorts.

Inflammation provides a substrate for mechanisms that underlie the association of maternal diet during pregnancy with Attention Deficit-Hyperactivity Disorder (ADHD) symptoms in childhood. However, no previous study has quantified the proinflammatory potential of maternal diet as a risk factor for ADHD. Thus, we evaluated the association of maternal dietary inflammatory index (DII®) scores during pregnancy with ADHD symptoms in 4-year-old children born in two Mediterranean regions. We analyzed data from two population-based birth cohort studies-INMA (Environment and Childhood) four subcohorts in Spain (N = 2097), and RHEA study in Crete (Greece) (N = 444). The DII score of maternal diet was calculated based on validated food frequency questionnaires completed during pregnancy (12th and/or 32nd week of gestation). ADHD symptoms were assessed by ADHD-DSM-IV in INMA cohort and by ADHDT test in RHEA cohort, with questionnaires filled-out by teachers and parents, respectively. The associations between maternal DII and ADHD symptoms were analysed using multivariable-adjusted zero-inflated negative binomial regression models in each cohort study separately. Meta-analysis was conducted to combine data across the cohorts for fitting within one model. The DII was significantly higher in RHEA (RHEA = 2.09 [1.94, 2.24]) in comparison to INMA subcohorts (Asturias = - 1.52 [- 1.67, - 1.38]; Gipuzkoa = - 1.48 [- 1.64, - 1.33]; Sabadell = - 0.95 [- 1.07, - 0.83]; Valencia = - 0.76 [- 0.90, - 0.62]). Statistically significant reduced risk of inattention symptomatology (OR = 0.86; CI 95% = 0.77-0.96), hyperactivity symptomatology (OR = 0.82; CI 95% = 0.72-0.92) and total ADHD symptomatology (OR = 0.82; CI 95% = - 0.72 to 0.93) were observed with increased maternal DII in boys. No statistically significant associations were observed in girls between maternal DII and inattention, hyperactivity and total ADHD symptomatology. We found reduced risk of ADHD symptomatology with increased DII only in boys. This relationship requires further exploration in other settings.

Cord blood metabolic signatures predictive of childhood overweight and rapid growth.

INTRODUCTION: Metabolomics may identify biological pathways predisposing children to the risk of overweight and obesity. In this study, we have investigated the cord blood metabolic signatures of rapid growth in infancy and overweight in early childhood in four European birth cohorts. METHODS: Untargeted liquid chromatography-mass spectrometry metabolomic profiles were measured in cord blood from 399 newborns from four European cohorts (ENVIRONAGE, Rhea, INMA and Piccolipiu). Rapid growth in the first year of life and overweight in childhood was defined with reference to WHO growth charts. Metabolome-wide association scans for rapid growth and overweight on over 4500 metabolic features were performed using multiple adjusted logistic mixed-effect models and controlling the false discovery rate (FDR) at 5%. In addition, we performed a look-up analysis of 43 pre-annotated metabolites, previously associated with birthweight or rapid growth. RESULTS: In the Metabolome-Wide Association Study analysis, we identified three and eight metabolites associated with rapid growth and overweight, respectively, after FDR correction. Higher levels of cholestenone, a cholesterol derivative produced by microbial catabolism, were predictive of rapid growth (p = 1.6 × 10-3). Lower levels of the branched-chain amino acid (BCAA) valine (p = 8.6 × 10-6) were predictive of overweight in childhood. The area under the receiver operator curve for multivariate prediction models including these metabolites and traditional risk factors was 0.77 for rapid growth and 0.82 for overweight, compared with 0.69 and 0.69, respectively, for models using traditional risk factors alone. Among the 43 pre-annotated metabolites, seven and five metabolites were nominally associated (P < 0.05) with rapid growth and overweight, respectively. The BCAA leucine, remained associated (1.6 × 10-3) with overweight after FDR correction. CONCLUSION: The metabolites identified here may assist in the identification of children at risk of developing obesity and improve understanding of mechanisms involved in postnatal growth. Cholestenone and BCAAs are suggestive of a role of the gut microbiome and nutrient signalling respectively in child growth trajectories.

Prenatal Exposure to Perfluoroalkyl Substances Associated With Increased Susceptibility to Liver Injury in Children.

BACKGROUND AND AIMS: Per- and polyfluoroalkyl substances (PFAS) are widespread and persistent pollutants that have been shown to have hepatotoxic effects in animal models. However, human evidence is scarce. We evaluated how prenatal exposure to PFAS associates with established serum biomarkers of liver injury and alterations in serum metabolome in children. APPROACH AND RESULTS: We used data from 1,105 mothers and their children (median age, 8.2 years; interquartile range, 6.6-9.1) from the European Human Early-Life Exposome cohort (consisting of six existing population-based birth cohorts in France, Greece, Lithuania, Norway, Spain, and the United Kingdom). We measured concentrations of perfluorooctane sulfonate, perfluorooctanoate, perfluorononanoate, perfluorohexane sulfonate, and perfluoroundecanoate in maternal blood. We assessed concentrations of alanine aminotransferase, aspartate aminotransferase, and gamma-glutamyltransferase in child serum. Using Bayesian kernel machine regression, we found that higher exposure to PFAS during pregnancy was associated with higher liver enzyme levels in children. We also measured child serum metabolomics through a targeted assay and found significant perturbations in amino acid and glycerophospholipid metabolism associated with prenatal PFAS. A latent variable analysis identified a profile of children at high risk of liver injury (odds ratio, 1.56; 95% confidence interval, 1.21-1.92) that was characterized by high prenatal exposure to PFAS and increased serum levels of branched-chain amino acids (valine, leucine, and isoleucine), aromatic amino acids (tryptophan and phenylalanine), and glycerophospholipids (phosphatidylcholine [PC] aa C36:1 and Lyso-PC a C18:1). CONCLUSIONS: Developmental exposure to PFAS can contribute to pediatric liver injury.

Heterogeneous associations of polyomaviruses and herpesviruses with allergy-related phenotypes in childhood.

BACKGROUND: Evidence suggests a complex interplay between infections and allergic diseases. OBJECTIVE: To explore the association of 14 common viruses with eczema, asthma, and rhinoconjunctivitis in childhood. METHODS: We used cross-sectional (n = 686) and prospective (n = 440) data from children participating in the Rhea birth cohort. Immunoglobulin G to polyomaviruses (BK polyomavirus, JC polyomavirus, KI polyomavirus [KIPyV], WU polyomavirus [WUPyV], human polyomavirus 6, human polyomavirus 7, Trichodysplasia spinulosa polyomavirus, Merkel cell polyomavirus, human polyomavirus 9, and human polyomavirus 10) and herpesviruses (Epstein-Barr virus, Cytomegalovirus, Herpes simplex virus-1, Herpes simplex virus-2) were measured at age 4 years by fluorescent bead-based multiplex serology. Definitions of eczema, asthma, and rhinoconjunctivitis at ages 4 and 6 years were based on questionnaires. Mediation of the associations by immune biomarkers was tested. RESULTS: Less likely to have eczema at age 4 years were KIPyV-seropositive (odds ratio [OR], 0.47; 95% confidence interval [CI], 0.27-0.82) and human polyomavirus 6 (OR, 0.44; 95% CI, 0.26-0.73) compared with their seronegative counterparts. Seropositivity to Epstein-Barr virus was negatively associated with eczema at age 4 years (OR, 0.39; 95% CI, 0.22-0.67) and 6 years (OR, 0.50; 95% CI, 0.25-0.99). Children with a higher burden of herpesviruses or of skin polyomaviruses had the lowest odds of eczema at age 4 years. Higher odds for asthma at age 4 years were found for WUPyV-seropositive children (OR, 3.98; 95% CI, 1.38-11.51), and for children seropositive to both respiratory polyomaviruses (KIPyV and WUPyV) (OR, 7.35; 95% CI, 1.66-32.59) compared with children seronegative to both. No associations were observed for rhinoconjunctivitis. There was no evidence of mediation by immune biomarkers. CONCLUSION: A heterogeneous pattern of infections and allergic diseases was observed with common infections associated with a decreased eczema risk and an increased asthma risk in children.

The EU Child Cohort Network's core data: establishing a set of findable, accessible, interoperable and re-usable (FAIR) variables.

The Horizon2020 LifeCycle Project is a cross-cohort collaboration which brings together data from multiple birth cohorts from across Europe and Australia to facilitate studies on the influence of early-life exposures on later health outcomes. A major product of this collaboration has been the establishment of a FAIR (findable, accessible, interoperable and reusable) data resource known as the EU Child Cohort Network. Here we focus on the EU Child Cohort Network's core variables. These are a set of basic variables, derivable by the majority of participating cohorts and frequently used as covariates or exposures in lifecourse research. First, we describe the process by which the list of core variables was established. Second, we explain the protocol according to which these variables were harmonised in order to make them interoperable. Third, we describe the catalogue developed to ensure that the network's data are findable and reusable. Finally, we describe the core data, including the proportion of variables harmonised by each cohort and the number of children for whom harmonised core data are available. EU Child Cohort Network data will be analysed using a federated analysis platform, removing the need to physically transfer data and thus making the data more accessible to researchers. The network will add value to participating cohorts by increasing statistical power and exposure heterogeneity, as well as facilitating cross-cohort comparisons, cross-validation and replication. Our aim is to motivate other cohorts to join the network and encourage the use of the EU Child Cohort Network by the wider research community.

Prenatal metal mixtures and child blood pressure in the Rhea mother-child cohort in Greece.

BACKGROUND: Child blood pressure (BP) is predictive of future cardiovascular risk. Prenatal exposure to metals has been associated with higher BP in childhood, but most studies have evaluated elements individually and measured BP at a single time point. We investigated impacts of prenatal metal mixture exposures on longitudinal changes in BP during childhood and elevated BP at 11 years of age. METHODS: The current study included 176 mother-child pairs from the Rhea Study in Heraklion, Greece and focused on eight elements (antimony, arsenic, cadmium, cobalt, lead, magnesium, molybdenum, selenium) measured in maternal urine samples collected during pregnancy (median gestational age at collection: 12 weeks). BP was measured at approximately 4, 6, and 11 years of age. Covariate-adjusted Bayesian Varying Coefficient Kernel Machine Regression and Bayesian Kernel Machine Regression (BKMR) were used to evaluate metal mixture impacts on baseline and longitudinal changes in BP (from ages 4 to 11) and the development of elevated BP at age 11, respectively. BKMR results were compared using static versus percentile-based cutoffs to define elevated BP. RESULTS: Molybdenum and lead were the mixture components most consistently associated with BP. J-shaped relationships were observed between molybdenum and both systolic and diastolic BP at age 4. Similar associations were identified for both molybdenum and lead in relation to elevated BP at age 11. For molybdenum concentrations above the inflection points (~ 40-80 µg/L), positive associations with BP at age 4 were stronger at high levels of lead. Lead was positively associated with BP measures at age 4, but only at high levels of molybdenum. Potential interactions between molybdenum and lead were also identified for BP at age 11, but were sensitive to the cutoffs used to define elevated BP. CONCLUSIONS: Prenatal exposure to high levels of molybdenum and lead, particularly in combination, may contribute to higher BP at age 4. These early effects appear to persist throughout childhood, contributing to elevated BP in adolescence. Future studies are needed to identify the major sources of molybdenum and lead in this population.

Gestational Weight Gain by Maternal Pre-pregnancy BMI and Childhood Problem Behaviours in School-Age Years: A Pooled Analysis of Two European Birth Cohorts.

OBJECTIVES: Maternal pre-pregnancy weight is known to affect foetal development. However, it has not yet been clarified if gestational weight gain is associated with childhood behavioural development. METHODS: We performed a pooled analysis of two prospective birth cohorts to investigate the association between gestational weight gain and childhood problem behaviours, and the effect modification of maternal pre-pregnancy BMI. In total, 378 mother-child pairs from the Maastricht Essential Fatty Acids Birth cohort (MEFAB) and 414 pairs from the Rhea Mother-Child cohort were followed up from early pregnancy to 6-7 years post-partum. At follow up, parents assessed their children's behaviour, measured as total problems, internalizing and externalizing behaviours, with the Child Behaviour Checklist. We computed cohort- and subject-specific gestational weight gain trajectories using mixed-effect linear regression models. Fractional polynomial regressions, stratified by maternal pre-pregnancy BMI status, were then used to examine the association between gestational weight gain and childhood problem behaviours. RESULTS: In the pre-pregnancy overweight/obese group, greater gestational weight gain was associated with higher problem behaviours. On average, children of women with overweight/obesity who gained 0.5 kg/week scored 25 points higher (on a 0-100 scale) in total problems and internalizing behaviours, and about 18 points higher in externalizing behaviours than children whose mothers gained 0.2 kg/week. Inconsistent results were found in the pre-pregnancy normal weight group. CONCLUSIONS FOR PRACTICE: Excessive gestational weight gain in women with pre-pregnancy overweight/obesity might increase problem behaviours in school-age children. Particular attention should be granted to avoid excessive weight gain in women with a pre-pregnancy overweight or obesity.

Associations of Prenatal Exposure to Cadmium With Child Growth, Obesity, and Cardiometabolic Traits.

Prenatal cadmium exposure has been associated with impaired fetal growth; much less is known about the impact during later childhood on growth and cardiometabolic traits. To elucidate the associations of prenatal cadmium exposure with child growth, adiposity, and cardiometabolic traits in 515 mother-child pairs in the Rhea Mother-Child Study cohort (Heraklion, Greece, 2007-2012), we measured urinary cadmium concentrations during early pregnancy and assessed their associations with repeated weight and height measurements (taken from birth through childhood), waist circumference, skinfold thickness, blood pressure, and serum lipid, leptin, and C-reactive protein levels at age 4 years. Adjusted linear, Poisson, and mixed-effects regression models were used, with interaction terms for child sex and maternal smoking added. Elevated prenatal cadmium levels (third tertile of urinary cadmium concentration (0.571-2.658 µg/L) vs. first (0.058-0.314 µg/L) and second (0.315-0.570 µg/L) tertiles combined) were significantly associated with a slower weight trajectory (per standard deviation score) in all children (ß = -0.17, 95% confidence interval (CI): -0.32, -0.02) and a slower height trajectory in girls (ß = -0.30, 95% CI: -0.52,-0.09; P for interaction = 0.025) and in children born to mothers who smoked during pregnancy (ß = -0.48, 95% CI: -0.83, -1.13; P for interaction = 0.027). We concluded that prenatal cadmium exposure was associated with delayed growth in early childhood. Further research is needed to understand cadmium-related sex differences and the role of coexposure to maternal smoking during early pregnancy.

Determinants of the urinary and serum metabolome in children from six European populations.

BACKGROUND: Environment and diet in early life can affect development and health throughout the life course. Metabolic phenotyping of urine and serum represents a complementary systems-wide approach to elucidate environment-health interactions. However, large-scale metabolome studies in children combining analyses of these biological fluids are lacking. Here, we sought to characterise the major determinants of the child metabolome and to define metabolite associations with age, sex, BMI and dietary habits in European children, by exploiting a unique biobank established as part of the Human Early-Life Exposome project ( http://www.projecthelix.eu ). METHODS: Metabolic phenotypes of matched urine and serum samples from 1192 children (aged 6-11) recruited from birth cohorts in six European countries were measured using high-throughput 1H nuclear magnetic resonance (NMR) spectroscopy and a targeted LC-MS/MS metabolomic assay (Biocrates AbsoluteIDQ p180 kit). RESULTS: We identified both urinary and serum creatinine to be positively associated with age. Metabolic associations to BMI z-score included a novel association with urinary 4-deoxyerythreonic acid in addition to valine, serum carnitine, short-chain acylcarnitines (C3, C5), glutamate, BCAAs, lysophosphatidylcholines (lysoPC a C14:0, lysoPC a C16:1, lysoPC a C18:1, lysoPC a C18:2) and sphingolipids (SM C16:0, SM C16:1, SM C18:1). Dietary-metabolite associations included urinary creatine and serum phosphatidylcholines (4) with meat intake, serum phosphatidylcholines (12) with fish, urinary hippurate with vegetables, and urinary proline betaine and hippurate with fruit intake. Population-specific variance (age, sex, BMI, ethnicity, dietary and country of origin) was better captured in the serum than in the urine profile; these factors explained a median of 9.0% variance amongst serum metabolites versus a median of 5.1% amongst urinary metabolites. Metabolic pathway correlations were identified, and concentrations of corresponding metabolites were significantly correlated (r > 0.18) between urine and serum. CONCLUSIONS: We have established a pan-European reference metabolome for urine and serum of healthy children and gathered critical resources not previously available for future investigations into the influence of the metabolome on child health. The six European cohort populations studied share common metabolic associations with age, sex, BMI z-score and main dietary habits. Furthermore, we have identified a novel metabolic association between threonine catabolism and BMI of children.

Does early onset asthma increase childhood obesity risk? A pooled analysis of 16 European cohorts.

The parallel epidemics of childhood asthma and obesity over the past few decades have spurred research into obesity as a risk factor for asthma. However, little is known regarding the role of asthma in obesity incidence. We examined whether early-onset asthma and related phenotypes are associated with the risk of developing obesity in childhood.This study includes 21 130 children born from 1990 to 2008 in Denmark, France, Germany, Greece, Italy, The Netherlands, Spain, Sweden and the UK. We followed non-obese children at 3-4 years of age for incident obesity up to 8 years of age. Physician-diagnosed asthma, wheezing and allergic rhinitis were assessed up to 3-4 years of age.Children with physician-diagnosed asthma had a higher risk for incident obesity than those without asthma (adjusted hazard ratio (aHR) 1.66, 95% CI 1.18-2.33). Children with active asthma (wheeze in the last 12 months and physician-diagnosed asthma) exhibited a higher risk for obesity (aHR 1.98, 95% CI 1.31-3.00) than those without wheeze and asthma. Persistent wheezing was associated with increased risk for incident obesity compared to never wheezers (aHR 1.51, 95% CI 1.08-2.09).Early-onset asthma and wheezing may contribute to an increased risk of developing obesity in later childhood.

Is early life exposure to polyomaviruses and herpesviruses associated with obesity indices and metabolic traits in childhood?

BACKGROUND: Evidence for an infectious origin of obesity is emerging. We explored whether common viruses were associated with obesity and metabolic traits. METHODS: We used cross-sectional (n = 674) and prospective (n = 440) data from children participating at the 4 and 6 years of age follow-up in the Rhea birth cohort. Presence of IgG antibodies to ten polyomaviruses (BKPyV, JCPyV, KIPyV, WUPyV, HPyV6, HPyV7, TSPyV, MCPyV, HPyV9, and HPyV10) and four herpesviruses (EBV, CMV, HSV-1, and HSV-2) were measured at age 4. Body mass index, waist circumference, and skinfold thickness were measured at age 4 and 6. Data on serum lipids, leptin, and adiponectin were also available. Multivariable linear regression models were used to explore the associations. RESULTS: At 4 years of age, seroprevalence to polyomaviruses ranged from 21.0% for HPyV9 to 82.0% for HPyV10. Seroprevalence for EBV, CMV, HSV-1, and HSV-2 was 53.0%, 26.0%, 3.6%, and 1.5% respectively. BKPyV seropositivity was associated with lower BMI SD score at age 4 [-0.21 (95% CI: -0.39, -0.03)] and 6 [-0.27 (95% CI:-0.48, -0.05)], waist circumference at age 4 [-1.12 cm (95% CI: -2.10, -0.15)] and 6 [-1.73 cm (95% CI: -3.33, -0.12)], sum of four skinfolds [-2.97 mm (95% CI: -5.70, -0.24)], and leptin levels at age 4 [ratio of geometric means, 0.83 (95% CI: 0.70, 0.98)]. CMV seropositivity was associated with higher BMI SD score at age 4 [0.28 (95% CI: 0.11, 0.45)] and 6 [0.24 (95% CI: 0.03, 0.45)] and sum of four skinfolds at age 6 [4.75 mm (95% CI: 0.67, 8.83)]. Having "2-3 herpesviruses infections" (versus "0 herpesvirus infections") was associated with higher BMI SD score [0.32, (95% CI: 0.12, 0.53)], waist circumference [1.22 cm (95% CI: 0.13, 2.31)], and sum of four skinfolds [3.26 mm (95% CI: 0.18, 6.35)] at age 4. Polyomaviruses burden was not associated with outcomes. CONCLUSIONS: A higher herpesviruses burden and CMV seropositivity were associated with obesity traits in childhood.

Maternal diet during pregnancy and micronuclei frequency in peripheral blood T lymphocytes in mothers and newborns (Rhea cohort, Crete).

PURPOSE: The study assessed whether diet and adherence to cancer prevention guidelines during pregnancy were associated with micronucleus (MN) frequency in mothers and newborns. MN is biomarkers of early genetic effects that have been associated with cancer risk in adults. METHODS: A total of 188 mothers and 200 newborns from the Rhea cohort (Greece) were included in the study. At early-mid pregnancy, we conducted personal interviews and a validated food frequency questionnaire was completed. With this information, we constructed a score reflecting adherence to the World Cancer Research Fund/American Institute for Cancer Research cancer prevention guidelines on diet, physical activity and body fatness. At delivery, maternal and/or cord blood was collected to measure DNA and hemoglobin adducts of dietary origin and frequencies of MN in binucleated and mononucleated T lymphocytes (MNBN and MNMONO). RESULTS: In mothers, higher levels of red meat consumption were associated with increased MNBN frequency [2nd tertile IRR = 1.34 (1.00, 1.80), 3rd tertile IRR = 1.33 (0.96, 1.85)] and MNMONO frequency [2nd tertile IRR = 1.53 (0.84, 2.77), 3rd tertile IRR = 2.69 (1.44, 5.05)]. The opposite trend was observed for MNBN in newborns [2nd tertile IRR = 0.64 (0.44, 0.94), 3rd tertile IRR = 0.68 (0.46, 1.01)], and no association was observed with MNMONO. Increased MN frequency in pregnant women with high red meat consumption is consistent with previous knowledge. CONCLUSIONS: Our results also suggest exposure to genotoxics during pregnancy might affect differently mothers and newborns. The predictive value of MN as biomarker for childhood cancer, rather than adulthood, remains unclear. With few exceptions, the association between maternal carcinogenic exposures during pregnancy and childhood cancer or early biologic effect biomarkers remains poorly understood.

Patterns of Early-Life Social and Environmental Exposures and Child Cognitive Development, Rhea Birth Cohort, Crete, Greece.

Early-life exposures are critical for later child cognitive development. McCarthy Scales of Children's Abilities (MSCA) were used to assess cognitive development of 700 preschoolers (Mage  = 4.2 years), derived from the "Rhea" birth cohort, in Greece. Principal component analysis (PCA) was applied on prospectively collected exposure data. Six components were extracted; five of them were associated with child cognition. Higher parental social status, preschool attendance and less TV watching, nonsmoking during pregnancy and breastfeeding, and parental involvement in child life were protective factors of child cognition at 4 years. Increased child birth order was negatively associated with child cognition. Offspring's size at birth was not associated with any cognitive outcome. These findings reveal the importance of early-life exposures to child cognitive development.

High maternal vitamin D levels in early pregnancy may protect against behavioral difficulties at preschool age: the Rhea mother-child cohort, Crete, Greece.

Animal studies suggest that prenatal vitamin D status may affect fetal brain growth. However, human studies are scarce with conflicting results. We aimed to investigate the association of maternal 25-hydroxyvitamin D [25(OH) D] levels with multiple neurodevelopmental outcomes at 4 years of age. We included 487 mother-child pairs from the prospective pregnancy cohort, "Rhea" in Crete, Greece. Maternal serum 25(OH) D concentrations were measured at the first prenatal visit (13 ± 2.4 weeks). Cognitive functions at 4 years were assessed by means of the McCarthy Scales of Children's Abilities. Behavioral difficulties were assessed by means of Strengths and Difficulties Questionnaire and Attention Deficit Hyperactivity Disorder Test. Children of women in the high 25(OH) D tertile (>50.7 nmol/l) had 37% decreased number of hyperactivity-impulsivity symptoms (IRR 0.63, 95% CI 0.39, 0.99, p trend = 0.05) and 40% decreased number of total ADHD-like symptoms (IRR 0.60, 95% CI 0.37, 0.95, p trend = 0.03) at 4 years of age, compared to children of women in the low 25(OH) D tertile (<38.4 nmol/l), after adjustment for several confounders. Similar associations were found with the hyperactivity/inattention score of the SDQ questionnaire. Children of mothers with high 25(OH) D levels had also fewer total behavioral difficulties (beta-coeff: -1.25, 95% CI -2.32, -0.19) and externalizing symptoms (beta-coeff: -0.87, 95% CI -1.58, -0.15) at preschool age. The observed associations were stronger in girls than in boys (p for interaction < 0.1). No association was observed between maternal 25(OH) D concentrations and cognitive function in preschoolers. Our results suggest that high maternal vitamin D levels in early pregnancy may protect against behavioral difficulties, especially ADHD-like symptoms at preschool age.