CONTEXT:Accurately assessing dietary intake in children and adolescents is challenging due to the limitations of traditional self-reported methods. Metabolomics has emerged as a valuable tool for assessing the body's biochemical response to specific foods, food groups, or dietary patterns, thereby improving the evaluation of diet-health relationships. However, evidence on how diet influences metabolomic profiles in pediatric populations remains limited. OBJECTIVE:To evaluate the evidence on the relationship between nutritional interventions or habitual dietary intake and metabolites measured in blood or urine among children and adolescents. DATA SOURCES:A systematic search was conducted in PubMed, Cochrane, and Embase databases up to September 2024. DATA EXTRACTION:This systematic review was conducted in accordance with the principles of the Cochrane Collaboration, and PRISMA guidelines were followed. Randomized clinical trials and observational studies in children and adolescents were included. DATA ANALYSIS:From 659 records, 8 studies met the inclusion criteria, involving 5992 participants across 12 countries. The included studies reported associations across 3 dietary categories: dietary patterns, food groups, and specific food ingredients. Both targeted and untargeted metabolomic analyses were used to identify diet-related biomarkers in blood and urine. Positive associations were observed between higher adherence to the Mediterranean diet and greater fruit and vegetable consumption with metabolites such as hippurate, trigonelline, and proline betaine. In contrast, higher intake of ultra-processed foods and adherence to vegan diets were inversely associated with branched-chain amino acids and aromatic amino acids such as tyrosine and docosahexaenoic acid. CONCLUSION:This review identifies several metabolites consistently associated with specific dietary components across different studies in children and adolescents. These findings support the potential of metabolomics for validating dietary biomarkers and improving the accuracy of dietary assessment in pediatric populations. Although metabolomic markers reflect actual dietary intake, their implications for health outcomes remain to be explored. SYSTEMATIC REVIEW REGISTRATION:PROSPERO registration no. CRD42024506437.

BACKGROUND AND AIM:Early-life nutrition plays a critical role in long-term health. Although complementary feeding has been widely studied, the influence of portion size during this stage on subsequent overweight risk remains unclear. This study aimed to evaluate whether portion size during complementary feeding is associated with overweight risk in childhood and preadolescence. METHODS:Secondary analysis of the European Childhood Obesity Project, a randomised clinical trial across five European countries. Dietary data was collected at 6, 12, 18 and 24 months using 3-day food records and food portions standardised as internal z-scores; anthropometry was assessed at 2, 8 and 11 years. Associations between early portion size and later overweight were examined using logistic regression (adjusted for feeding type, country, parental education, birth weight, meal frequency and energy intake) and structural equation modelling. RESULTS:Larger portion sizes at 6 months were associated with more than a twofold higher risk of overweight at 2 years (OR 2.36, p = 0.031). Portion size at later complementary feeding stages showed positive trends with overweight at 2, 8 and 11 years and indirect associations with overweight at 8 and 11 years mediated by portion size at 8 years. CONCLUSION:Larger portion sizes early in life are associated with increased risk of overweight later in childhood. These findings highlight portion size guidance during complementary feeding as a potential early target for obesity prevention.

Diet during early infancy, as well as dietary patterns during childhood and parental feeding styles influence children’s eating behaviours and long-term health. While extensive data exist on the timing of complementary feeding introduction and recommended food frequencies during infancy and childhood, data on portion sizes during this period remains limited in Europe, despite their clear relevance for evaluating dietary patterns and supporting evidence-based guidance. This longitudinal study, secondary to the European Childhood Obesity Project (EU CHOP), aims to describe portion sizes consumed by infants and children aged 6 months to 8 years across five European countries. Dietary intake was recorded using 3-day food diaries and analysed by trained personnel following standardized procedures at multiple infant and childhood ages (6, 7, 8, 9, 12, 24, 36, 48, 60, 72 and 96 months). Portions sizes were calculated for 33 food groups and expressed as percentiles in the overall sample and stratified by country. A total of 1018 3-day food records were available at 6 months, with sample size gradually declining over the 11 follow-up time points to 400 records at 8 years. The results revealed a wide variation in portion sizes across food groups, ages and countries. Food portion sizes vary across food groups, age and countries. These findings provide reference percentiles representing typical portion sizes when foods are consumed. The data can support guidance provided to parents by healthcare professionals (pediatricians, nurses, and dietitian-nutritionists) and assist public health authorities in defining appropriate portion sizes and mitigating risks associated with both overeating and undereating, while respecting children’s hunger and satiety cues. These results also have practical applications in school meal planning and dietary assessment methodologies in research.

BACKGROUND:Socioeconomic inequalities in children's emotional and behavioural problems are already present at school entry. We examined associations between early-life socioeconomic conditions and children's externalising and internalising problems and assessed whether early-life risk factors mediated these associations. METHODS:We analysed harmonised individual participant data from eight birth cohorts within the EU Child Cohort Network. Maternal educational level during pregnancy was used as an indicator of early-life socioeconomic conditions (SECs). Scores of children's externalising and internalising problems around school entry age were used as the outcome variables. Inequalities were quantified using the Slope Index of Inequality which captures the difference in prevalence of problems between children from highest and lowest SECs. Mediation analysis was used to assess the mediating role of five early-life risk factors: maternal smoking during pregnancy, gestational age, small for gestational age, postpartum depression and breastfeeding. RESULTS:Inequalities in externalising and internalising problems by SECs were consistent across cohorts: Children of mothers with low educational level had on average a 12 and 11 percentage point increased prevalence of externalising and internalising problems respectively. Early-life factors explained around 8% (DNBC, Denmark) to 54% (INMA, Spain) of the inequality in externalising problems and 7% (ELFE, France) to 25% (ALSPAC, UK) in internalising problems. CONCLUSIONS:Children from lower SECs consistently had a higher prevalence of both externalising and internalising problems around school entry age. These inequalities were partly mediated by early-life factors. Public health interventions in pregnancy and the preschool period are critical to address the early emergence of inequalities in children's mental health.

BACKGROUND:Gut microbiota imbalances may contribute to obesity, yet whether dietary interventions can modulate the microbiota and improve metabolic health in pediatrics has not been thoroughly reviewed. This systematic review and meta-analysis explores the impact of dietary interventions on the gut microbiota of children and adolescents with overweight or obesity, and its association with cardiometabolic improvements. METHODS:A systematic search of clinical trials in Pubmed, Cochrane and EMBASE was conducted following PRISMA guidelines (PROSPERO n°CRD42024505494). Risk of bias was assessed with RoB2 and ROBINS, for randomized and non-randomized intervention studies. RESULTS:Overall, 60 articles were assessed for full-text eligibility, 8 were included, and 4 provided alpha-diversity data for meta-analysis. A total of 200 participants were included (6-16 years). Six studies implemented calorie-restricted diets, one a low free-sugar diet, and one CHILD-1 diet. The meta-analysis revealed a significant increase in Chao1 (48.76 [95%CI 1.81; 95.70]; I2 = 86.8%, p < 0.001) following a balanced calorie-restricted dietary intervention. Although there was heterogeneity in taxa-level changes, several butyrate-producing genera (Clostridium XVIa, Coprococcus, Roseburia, Faecalibacterium, Blautia, Butyricimonas) increased following dietary intervention. CONCLUSIONS:Balanced dietary interventions with calorie-restriction adequate for pediatric age could increase gut microbiota richness and butyrate-producing bacteria abundance. Future trials should clarify diet-driven gut microbiota changes in childhood obesity and related metabolic changes. IMPACT:Balanced calorie restriction diet may increase gut microbiota richness in childhood obesity Butyrate-producer expansion needs long-term dietary intervention Gaps in linking microbiota-metabolism interplay in pediatric obesity.

CONTEXT:Childhood obesity is a major global health concern, with various strategies aimed at prevention. Early childhood represents a critical window for intervention; however, the effectiveness of strategies during this period remains unclear. OBJECTIVE:To evaluate the effectiveness of interventions implemented during the first 3 years of life in preventing childhood overweight and obesity, through a systematic review of reviews. DATA SOURCES:A systematic review of systematic reviews and meta-analyses was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Reviews targeting children up to 3 years of age in Organization for Economic Co-operation and Development countries were included. DATA EXTRACTION:The primary outcomes were the incidence of overweight and obesity, assessed at least 1 year postintervention. Secondary outcomes included body mass index z-score, weight-gain velocity, and body composition. The quality of the reviews was assessed using the AMSTAR-2 tool. DATA ANALYSIS:Thirty-nine systematic reviews were included in the qualitative synthesis, from which only 45 randomized controlled trials were identified as meeting the inclusion criteria. Evidence suggests that multicomponent interventions incorporating physical activity or responsive feeding show modest positive effects, although the quality of evidence is generally low. Reducing protein intake from infant formula during the first 2 years of life showed moderate evidence in reducing obesity risk up to 6 years of age. Breastfeeding, sleep, and weaning interventions had limited or inconclusive effects. CONCLUSION:While reducing protein intake from infant formula during the first 2 years of life showed moderate evidence of benefit, there is limited and low-quality evidence supporting early-life interventions to prevent childhood obesity. Multicomponent interventions, particularly those incorporating physical activity or promoting responsive feeding, appear modestly beneficial. Further high-quality research, particularly randomized clinical trials with longer follow-up, is needed to confirm these findings and optimize obesity-prevention strategies. SYSTEMATIC REVIEW REGISTRATION:PROSPERO registration no. CRD42022338940.

BACKGROUND AND AIMS:Atopic dermatitis (AD) poses a substantial burden on affected children and their families. The evidence of the role of feeding choices in infancy for AD development is limited. METHODS:This study is a two-arm, parallel, randomized, double-blind, controlled trial to assess the effect of infant feeding with whole goat milk formula (WGF) versus cow milk formula (CF) on AD development during the first year of life. Healthy term infants up to 3 months of age were enrolled in 6 Spanish and 4 Polish study centres, without AD risk selection. The primary outcome measure was AD diagnosed by study personnel at three study visits using the United Kingdom Working Party diagnostic criteria (ADPrimary). Reported doctor-diagnosed AD (ADDoctor) was a secondary outcome. Cumulative incidence in the first year of life was calculated. Incidence rate ratios (IRR) were estimated by Poisson regression. RESULTS:Data from 2132 infants were analyzed. 192 infants were diagnosed with ADPrimary and 245 with ADDoctor. The cumulative incidence rate of ADPrimary for both groups was 11.6 per 100 person-years without difference between WGF and CF (IRR: 1.00; 95%CI: 0.75, 1.32; p = 0.991). In the per-protocol population, the incidence of ADDoctor was lower in WGF than CF (IRR: 0.66; 95%CI: 0.49, 0.9; p = 0.008). In infants with parental history of AD, the protective effect of WGF was stronger: ADDoctor IRR 0.36 (95%CI: 0.17, 0.76; p = 0.007). CONCLUSION:This trial demonstrates that WGF can reduce the incidence of AD in formula-fed infants in the first year of life, especially in presence of parental history of AD. TRIAL REGISTRATION:ClinicalTrials.gov Identifier: NCT04599946. Submitted: 2020-10-05.

Air displacement plethysmography (ADP) estimates of fat mass (FM) and lean mass (LM) usually assume constant LM density, which may reduce accuracy in children with obesity. We aimed to validate FM and LM from ADP by adjusting LM density according to the degree of obesity at the one-year follow-up, and to assess their ability to track longitudinal changes. This prospective study included 37 children with obesity aged 9–14 years. Body composition was assessed before and after a 12-month intervention using four-component (4 C) model. FM and LM (Kg) from ADP assuming constant LM density (FMD−k and LMD−k) were compared with those from adjusted LM densities (LMD−adj and FMD−adj), and both compared to 4 C model. Cross-sectionally, ADP-adjusted model did not differ from 4 C model, whereas constant-density ADP did (p < 0.001). Bland–Altman plots showed better agreement with 4 C model for the adjusted method (FMD−adj -0.51 (-2.48, 1.46) vs. FMD−k -1.47 (-3.69, 0.75)). In longitudinal analysis, Bland-Altman plots indicated that the two ADP methods were highly consistent with those from the 4 C model (FMD−adj 0.24 (-2.02, 2.50) vs. FMD−k 0.07 (-2.25, 2.39)). Adjusting LM density according to obesity improves cross-sectional accuracy of ADP estimates, while longitudinal tracking performance remains similar between methods.

Background and Aim Maternal lifestyle factors during pregnancy may influence offspring risk of childhood overweight-obesity (OW-OB). Obesity is a heterogenous condition with different metabolic phenotypes; limited research on their associations with early-life exposures exists. We investigated associations of a composite maternal healthy lifestyle score (HLS) and offspring metabolic phenotypes throughout childhood. Methods and Results Study-specific analyses were conducted on mother-child dyads (n=6,088) from four European studies: two RCTs (secondary analysis) and two mother-child cohorts. The HLS was calculated based on pre-pregnancy BMI, and diet quality, physical activity, smoking status, and alcohol consumption during pregnancy. Children were classified as metabolically healthy/unhealthy phenotypes with underweight-normal weight or OW-OB, according to their BMI category and the absence/presence of at least one metabolic risk factor (high systolic or diastolic blood pressure, low HDL cholesterol, high triglycerides or elevated glucose concentrations). Maternal HLS associations with offspring metabolic health phenotypes at early (5-5.5 years), mid- (8-9 years) and late (11 years) childhood were assessed using multinomial logistic regressions.The majority of children were classified as metabolically healthy with underweight-normal weight, whereas metabolically healthy and unhealthy OW-OB children represented 3.5-13.6% and 3.9-14.8%, respectively. Consistently across studies, a higher maternal HLS was associated with a lower risk of offspring being metabolically unhealthy OW-OB across early, mid- and late childhood (RRR [95% CI] ranged from 0.43 [0.29, 0.65] to 0.80 [0.71, 0.91]). Associations with other phenotypes were less consistent. Conclusions Greater maternal adherence to healthy lifestyle behaviours during pregnancy was associated with a lower risk of metabolically unhealthy OW-OB among offspring. Trial Registration CHOP: EU-Childhood Obesity Project. NCT00338689. https://clinicaltrials.gov/, ROLO: Current Controlled Trials. ISRCTN54392969. https://www.isrctn.com/

BACKGROUND & OBJECTIVE:Responses to dietary interventions may vary depending on baseline gut microbiota composition. This study aimed to determine whether baseline gut microbiota diversity and composition predict the effectiveness of childhood obesity interventions. METHODS:Anthropometry, triglycerides, HDL-cholesterol, HOMA-IR, and systolic and diastolic blood pressure (SBP, DBP) were evaluated and standardised in 41 children with obesity (8-14yrs). Faecal samples were collected at baseline and after one year. Intervention success was defined by improvements in metabolic risk score (MetScore) or BMI z-score. Associations between baseline microbiota features (diversity and composition) and intervention success were evaluated using Spearman's correlation and linear regression models. Gut microbiota composition and differential abundance were analyzed using ANCOM-BC2. Exploratory biomarker discovery was analyzed using LEfSe, and predictive modelling using a Random Forest (RF) classifier. Receiver operating characteristic (ROC) curve analysis was used to determine a Simpson index cut-off. RESULTS:Higher baseline Shannon and Simpson indices, and greater abundances of Faecalibacterium and Eubacterium coprostanoligenes group, were associated with greater improvements in MetScore. Faecalibacterium was the most influential feature with the highest importance in the RF model, which achieved an AUC of 0.876 for MetScore and 0.873 for BMI z-score improvement. Eighty-four features differed between MetScore response groups (FDR < 0.05) with some genus-level overlap with the exploratory analysis, including Eubacterium coprostanoligenes and Ruminococcus. A Simpson index cut-off of 0.849 stratified participants high- and low-diversity groups; children above this threshold exhibited greater improvements in MetScore (p = 0.028), SBP (p = 0.043), and in HDL-cholesterol (p = 0.028). CONCLUSION:Higher baseline gut microbiota diversity and specific microbial signatures, particularly Faecalibacterium abundance, predicted better outcomes in childhood obesity interventions. These findings support the potential use of microbiota profiling to guide personalised treatment strategies. Further research is needed to optimise interventions.Trial registration: clinicaltrials.gov NCT03749291.

BACKGROUND AND AIMS:A previous randomized clinical trial showed that lower milk protein intake during infancy reduces body mass index (BMI) in early life and leads to lower rates of obesity in later childhood. The aim was to assess whether reducing protein intake during the second year of life lowers BMI at age 24 months.. METHODS:We randomly assigned 1624 healthy children at 12 months of age in Germany and Spain to receive isocaloric, cow's milk-based young child formula with either lower (LP; similar to breastmilk) or higher (HP; similar to cow's milk) protein concentration (1.5 or 6.1 g protein/100 kcal, respectively). Anthropometric outcomes were expressed as WHO age and sex-adjusted z-scores. The primary outcome was BMI z-score (zBMI) at 24 months adjusted for baseline zBMI, sex and country. Dietary intake was assessed by one-day 24 h recalls. RESULTS:1476 (90.9%) children completed the 24-months follow-up visit. Total protein intake was ∼30% lower in the LP than in the HP group during the intervention (mean at 18 months = 14 (SD ± 3)% vs. 18 (3)% of total energy, respectively). Children in the LP group maintained stable weight and length z-scores, while those in the HP group showed upward deviations relative to the WHO reference. At 24 months, zweight and zlength were significantly lower in LP than HP (mean difference -0.11, 95%CI -0.16,-0.06, p < 0.001; -0.13, 95%CI -0.19, -0.08, p < 0.001, respectively). zBMI at age 24 months was 0.38 (0.98) in LP and 0.39 (0.93) in HP (mean difference -0.034, 95%CI -0.097, 0.028; p = 0.281, ANCOVA); at 18 months of age the zBMI was significantly lower in LP (-0.073; 95%CI -0.126, -0.020, p = 0.007). CONCLUSION:Lower milk protein intake during the second year of life did not affect BMI at 24 months while transiently leading to a lower BMI at 18 months. Lower milk protein intake resulted in stable growth whereas higher protein intake augmented weight and height gain up to 2 years of age relative to reference values. This trial was registered on 31.08.2016 at clinicaltrials.gov as NCT02907502.

The insulin-like growth factor (IGF) axis is postulated to influence early-life adipocyte activity and lipolysis. We investigated whether IGF-1 and IGF-binding proteins (IGFBP-2, IGFBP-3) are associated with the lipids of healthy toddlers. Data were collected during the Toddler Milk Intervention trial to test the effect of milk protein on growth in the second year of life in Germany and Spain. Any blood values for IGF-1, IGFBP-2, IGFBP-3, low- and high-density lipoprotein cholesterol (LDL-C, HDL-C), total cholesterol (TC) and triglycerides (TG) were available at 12 and 24 months from 881 to 775 toddlers, respectively. These blood parameters were available from 444 children at both time points. Mixed intercept linear models adjusted for sex, fasting duration, country, and body mass index (BMI) were used to assess the associations between the IGF axis and lipids. BMI was 17.0 ± 1.4 kg/m2 (M ± SD) at 12 months. IGF-1, IGFBP-3 and IGFBP-2 levels were 75.9 ± 36.1 ng/ml, 2630.3 ± 638.4 ng/ml and 575.5 ± 245.6 ng/ml, respectively; the mean LDL-C, HDL-C, TC and TG levels were 80.5 ± 22.9 mg/dl, 42.2 ± 10.9 mg/dl, 141.7 ± 25.5 mg/dl and 101.2 ± 58.9 mg/dl, respectively. While the IGFBP-2 and TG levels were higher at 12 months (p < 0.001) compared to 24 months, all other parameters were lower (p < 0.05). IGF-1 and IGFBP-3 were weakly positively associated with LDL-C, HDL-C and TC, whereas IGFBP-2 was weakly negatively associated with LDL-C, HDL-C and TC. The IGF axis is weakly associated with circulating lipids. IGF-1 and its binding proteins seem to have a limited impact on lipid profiles of toddlers. Clinical trial registration number: NCT02907502, 26.04.2016.

BACKGROUND:Dietary habits influence health from childhood, with effects that may persist throughout life. This study aimed to investigate the association between dietary patterns and cardiometabolic risk markers in early childhood. METHODS:A cross-sectional analysis was performed within the Childhood Obesity Risk Assessment Longitudinal Study (CORALS) cohort. Diet was assessed by a validated food frequency questionnaire. Dietary patterns were extracted using exploratory factor analysis. Cardiometabolic risk was analysed through internal z-scores, body mass index (BMIz), systolic blood pressure, HDL cholesterol (HDLz), triglycerides and HOMA-IR, and multi-adjusted linear regression models were performed. RESULTS:The analysis included 1426 participants (median age 4.95 years). Two dietary patterns (DPs) were identified: "Core-foods DP" (high in vegetables, fruits, nuts, legumes, fish and white meat) and "Poor-quality DP" (rich in flavoured dairy products, processed meat, pastries, sweets, snacks, precooked foods, other oils and soft drinks). Core-foods DP was inversely associated with BMIz (B = -0.07, p = 0.034), meanwhile the Poor-quality DP was directly associated with triglycerides (B = 0.09, p = 0.015) and higher overweight odds (OR:1.33; 95% CI:1.13-1.56), and inversely with HDLz (B = -0.08, p = 0.036). CONCLUSION:Poor-quality DP was directly associated with cardiometabolic risk markers in preschool-aged children, emphasizing the importance of diet in preventing the early onset of obesity and cardiometabolic disorders. IMPACT:This study highlights the impact of dietary patterns on cardiometabolic health in preschool children. A poor-quality dietary pattern is directly associated with BMI and triglycerides and inversely associated with HDL cholesterol, which may contribute to a worse cardiometabolic profile. In contrast, adherence to a core-foods pattern is inversely associated with BMI. These findings reinforce the importance of early nutrition education in preventing obesity and cardiometabolic disorders. This article provides evidence of diet-related metabolic risks in early life to limited existing literature and the need for interventions that promote healthier eating habits from an early age to improve long-term health outcomes.

Childhood obesity remains a major global public health challenge, leading to significant short- and long-term adverse health outcomes and imposing substantial societal costs. Recognising the critical importance of early intervention, the Horizon2020 EU-funded JPI Consortium EndObesity has prioritised the first 1000 days of life, from preconception to 2 years of age, as a key window for obesity prevention strategies. This narrative review synthesises findings from the EndObesity Consortium, summarising evidence from large multi-cohort studies on the influence of family-based health behaviours in the first 1000 days on offspring obesity risk, the potential of childhood obesity prediction models in the first 1000 days, and strategies to enhance prenatal and postnatal interventions to prevent childhood obesity development. Finally, we present recommendations for research, practice, and policy to address the complex, multifaceted challenges of childhood obesity prevention in the first 1000 days.

Background Fetal and infant development might be critical for cognitive outcomes and psychopathology later in life. We assessed the associations of birth characteristics and early life growth with behavior and cognitive outcomes from childhood to adolescence. Methods We used harmonized data of 109,481 children from 8 European birth cohorts. Birth weight, gestational age, and body mass index (BMI) tertiles at the age of 2 years were used as the exposure variables. Outcomes included internalizing and externalizing problems and attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and non-verbal intelligence quotient (Non-verbal IQ) in childhood (4-10 years), early adolescence (11-16 years), and late adolescence (17-20 years). We used 1-stage individual participant data meta-analyses using generalized linear models. Findings A one-week older gestational age was associated with lower scores for internalizing problems (difference -0.48 (95% CI: -0.59, -0.37)), externalizing problems (difference -0.34 (95% CI: -0.44, -0.23)), and ADHD symptoms (difference -0.38 (95% CI: -0.49, -0.27)), and with higher scores for non-verbal IQ (difference 0.65 (95% CI: 0.41, 0.89)). As compared to term birth, preterm birth was associated with higher internalizing problems (difference 3.43 (95% CI: 2.52, 4.33)) and externalizing problems (difference 2.31 (95% CI: 1.16, 3.46)), ADHD symptoms (difference 4.15 (95% CI: 3.15, 5.16)), ASD symptoms (difference 3.23 (95% CI: 0.37, 6.08)), and lower non-verbal IQ (difference -5.44 (95% CI: -7.44, -3.44)). Small size for gestational age at birth (SGA) in comparison with appropriate size for gestational age (AGA) was associated with higher ADHD symptoms (difference 4.88 (95% CI: 3.87, 5.90)) and lower Non-verbal IQ (difference -7.02 (95% CI: -8.84, -5.21)). Large size for gestational age at birth was associated with lower ADHD symptoms (difference -1.09 (95% CI: -1.73, 0.45)) and higher non-verbal IQ (difference 2.47 (95% CI: 0.77, 4.18)). Explorative analyses showed that as compared to children with an appropriate size for gestational age at birth and a normal BMI at the age of 2 years, children born SGA who remained small at 2 years had the lowest non-verbal IQ score (difference -8.14 percentiles (95% CI: -11.89, -4.39)). Interpretation Both fetal and early childhood growth are associated with emotional, behavioral and cognitive outcomes throughout childhood and adolescence. Compensatory infant growth might partly attenuate the adverse effects of suboptimal fetal growth. Future studies are needed to identify the potential for optimizing mental health outcomes in new generations by improving early-life growth. Copyright (c) 2025 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Preschoolers and young children are vulnerable to psychosocial and behavioral disorders linked to lifestyle factors such as screen time and sleep disturbances. Our study examines the relationship between screen time and adherence to recommendations with children’s behavioral and emotional difficulties, with a focus on the role of sleep duration. Cross-sectional analyses were conducted within the multicenter prospective Childhood Obesity Risk Assessment Longitudinal Study (CORALS), which included 1420 children aged 3–6 years. Screen time (hours/day) and adherence to recommendations (≤ 2 hours/day) were assessed. Behavioral and emotional difficulties were measured via the strengths and difficulties questionnaire. Multivariable linear and logistic regression models were used to estimate associations between screen time (continuous and dichotomous) and strengths and difficulties questionnaire scores, adjusting for potential confounders. We also tested the moderating effect of sleep and conducted isotemporal substitution analyses replacing screen time with sleep duration. Higher screen time was associated with higher total strengths and difficulties questionnaire scores [β 95

Classification of physical activity (PA) depends on the cut-point method used to allocate PA counts from accelerometer measurements. This study investigates how three validated cut-point methods affect the time spent in various levels of PA and sedentary behaviour (SB), and how they impact toddlers estimated adherence to PA guidelines. PA was assessed using an ActiGraph wGT3X-BT accelerometer in a cohort of 653 two-year-old children participating in the Toddler Milk Intervention study. Children wearing the ActiGraph for at least four days, with a minimum of six hours wear-time per day, were included. Time spent in SB and different activity levels were estimated according to three cut-point methods and were standardized to individual mean wear-time. We used one cut-point method based on the vertical axis (VA) (Trost VA), with an epoch length of 15 s and two cut-point methods based on either the VA (Costa VA) or on the vector magnitude (VM) (Costa VM) with an epoch length of five seconds. Estimates of SB and PA for each method were compared with repeated measures ANOVA. The time toddlers spent in PA was significantly different depending on the cut-point methods. Costa VM classified on average 62 min (95