Underweight in the first 2 years of life and nutrition risk in later childhood: a prospective cohort study

BACKGROUND

Children with underweight in the first 2 years have lower body mass index z-score (zBMI) and height-for-age z-score (HAZ) in later childhood. It is not known if underweight in the first 2 years is associated with nutrition risk in later childhood.

OBJECTIVE

(1) Determine the relationship between underweight (zBMI < -2) in the first 2 years and nutrition risk measured by the Nutrition Screening for Toddlers and Preschoolers (NutriSTEP) score from 18 months to 5 years. (2) Explore the relationship between underweight in the first 2 years and the NutriSTEP subscores for eating behaviours and dietary intake from 18 months to 5 years.

METHODS

This was a prospective study, including healthy full-term children in Canada aged 0-5 years. zBMI was calculated using measured heights and weights and the WHO growth standards. NutriSTEP score was measured using a parent-completed survey and ranged from 0 to 68. Nutrition risk was defined as a score ≥21. Linear mixed effects models were used.

RESULTS

Four thousand nine hundred twenty-nine children were included in this study. At enrolment, 51.9% of participants were male. The prevalence of underweight children was 8.8%. Underweight in the first 2 years was associated with higher NutriSTEP (0.79, 95% CI: 0.29,1.29), higher eating behaviour subscore (0.24, 95% CI: 0.03, 0.46) at 3 years and higher odds of nutrition risk (OR: 1.39, 95% CI: 1.07,1.82) at 5 years.

CONCLUSIONS

Children with underweight in the first 2 years had higher nutrition risk in later childhood. Further research is needed to understand the factors which influence these relationships.

Haemoglobin thresholds to define anaemia from age 6 months to 65 years: estimates from international data sources

BACKGROUND

Detection of anaemia is crucial for clinical medicine and public health. Current WHO anaemia definitions are based on statistical thresholds (fifth centiles) set more than 50 years ago. We sought to establish evidence for the statistical haemoglobin thresholds for anaemia that can be applied globally and inform WHO and clinical guidelines.

METHODS

In this analysis we identified international data sources from populations in the USA, England, Australia, China, the Netherlands, Canada, Ecuador, and Bangladesh with sufficient clinical and laboratory information collected between 1998 and 2020 to obtain a healthy reference sample. Individuals with clinical or biochemical evidence of a condition that could reduce haemoglobin concentrations were excluded. We estimated haemoglobin thresholds (ie, 5th centiles) for children aged 6-23 months, 24-59 months, 5-11 years, and 12-17 years, and adults aged 18-65 years (including during pregnancy) for individual datasets and pooled across data sources. We also collated findings from three large-scale genetic studies to summarise genetic variants affecting haemoglobin concentrations in different ancestral populations.

FINDINGS

We identified eight data sources comprising 18 individual datasets that were eligible for inclusion in the analysis. In pooled analyses, the haemoglobin fifth centile was 104·4 g/L (90% CI 103·5-105·3) in 924 children aged 6-23 months, 110·2 g/L (109·5-110·9) in 1874 children aged 24-59 months, and 114·4 g/L (113·6-115·2) in 1839 children aged 5-11 years. Values diverged by sex in adolescents and adults. In pooled analyses, the fifth centile was 122·2 g/L (90% CI 121·3-123·1) in 1741 female adolescents aged 12-17 years and 128·2 g/L (126·4-130·0) in 1103 male adolescents aged 12-17 years. In pooled analyses of adults aged 18-65 years, the fifth centile was 119·7 g/L (90% CI 119·1-120·3) in 3640 non-pregnant females and 134·9 g/L (134·2-135·6) in 2377 males. Fifth centiles in pregnancy were 110·3 g/L (90% CI 109·5-111·0) in the first trimester (n=772) and 105·9 g/L (104·0-107·7) in the second trimester (n=111), with insufficient data for analysis in the third trimester. There were insufficient data for adults older than 65 years. We did not identify ancestry-specific high prevalence of non-clinically relevant genetic variants that influence haemoglobin concentrations.

INTERPRETATION

Our results enable global harmonisation of clinical and public health haemoglobin thresholds for diagnosis of anaemia. Haemoglobin thresholds are similar between sexes until adolescence, after which males have higher thresholds than females. We did not find any evidence that thresholds should differ between people of differering ancestries.

FUNDING

World Health Organization and the Bill & Melinda Gates Foundation.

The mediation effect of breastfeeding duration on the relationship between maternal preconception BMI and childhood nutritional risk

BACKGROUND

Higher maternal preconception body mass index (BMI) is associated with lower breastfeeding duration, which may contribute to the development of poor child eating behaviours and dietary intake patterns (components of nutritional risk). A higher maternal preconception BMI has been found to be associated with higher child nutritional risk. This study aimed to determine whether breastfeeding duration mediated the association between maternal preconception BMI and child nutritional risk.

METHODS

In this longitudinal cohort study, children ages 18 months to 5 years were recruited from The Applied Research Group for Kids (TARGet Kids!) in Canada. The primary outcome was child nutritional risk, using The NutriSTEP®, a validated, parent-reported questionnaire. Statistical mediation analysis was performed to assess whether total duration of any breastfeeding mediated the association between maternal preconception BMI and child nutritional risk.

RESULTS

This study included 4733 children with 8611 NutriSTEP® observations. The mean (SD) maternal preconception BMI was 23.6 (4.4) and the mean (SD) breastfeeding duration was 12.4 (8.0) months. Each 1-unit higher maternal preconception BMI was associated with a 0.081 unit higher nutritional risk (95% CI (0.051, 0.112); p < 0.001) (total effect), where 0.011(95% CI (0.006, 0.016); p < 0.001) of that total effect or 13.18% (95% CI: 7.13, 21.25) was mediated through breastfeeding duration.

CONCLUSION

Total breastfeeding duration showed to mediate part of the association between maternal preconception BMI and child nutritional risk. Interventions to support breastfeeding in those with higher maternal preconception BMI should be evaluated for their potential effect in reducing nutritional risk in young children.

Factors associated with COVID-19 vaccination in young children

OBJECTIVE

To examine factors associated with COVID-19 vaccination (time to vaccination and vaccination status) among healthy young children participating in primary healthcare.

METHODS

A cohort study was conducted between November 2021 and September 2022 through the TARGet Kids! primary care research network in Toronto, Canada. Sociodemographic information, child and parent health characteristics, parental vaccine beliefs and child COVID-19 vaccine uptake were collected through parent-reported questionnaires. The primary outcome was time to child COVID-19 vaccination, measured as the time between vaccine availability date and parent-reported child COVID-19 vaccination date. Interval-censored proportional hazard models were used.

RESULTS

A total of 267 children age 0 to 13 years were included. The mean child age was 7.6 years, 52.8% (n = 141) were male, 66.5% (n = 141) had mothers of European ethnicity (with missingness), and 68.2% (n = 182) of the children were vaccinated. All parents of vaccinated children had received the COVID-19 vaccination themselves. The rate of vaccination for children was 2% higher with each one-month increase in child age (adjusted HR = 1.02, 95%CI = 1.01-1.03, p < 0.001). Compared to children whose parents had uncertain beliefs, those whose parents had positive beliefs about the importance and safety of COVID-19 vaccination for their children had higher rates of vaccination (adjusted HR = 8.29, 95%CI = 4.25-16.17, p < 0.001; adjusted HR = 5.09, 95%CI = 3.17-8.17, p < 0.001).

CONCLUSION

Older child age, parental COVID-19 vaccination, and positive parental beliefs about COVID-19 vaccination were statistically significantly associated with COVID-19 vaccination among healthy young children. Our findings may help to inform policies, practices, and research which aim to strengthen parental vaccine confidence and promote child COVID-19 vaccination.

Association Between Family Income and Positive Developmental Screening Using the Infant Toddler Checklist at the 18-Month Health Supervision Visit

OBJECTIVE

To examine the associations between several potential predictors (child biologic, social, and family factors) and a positive screen for developmental delay using the Infant Toddler Checklist (ITC) at the 18-month health supervision visit in primary care.

METHODS

This was a cross-sectional study of healthy children attending an 18-month health supervision visit in primary care. Parents completed a standardized questionnaire, addressing child, social, and family characteristics, and the ITC. Logistic regression analyses were used to assess the associations between predictors and a positive ITC.

RESULTS

Among 2188 participants (45.5% female; mean age, 18.2 months), 285 (13%) had a positive ITC and 1903 (87%) had a negative ITC. The aOR for a positive ITC for male compared with female sex was 2.15 (95% CI, 1.63-2.83; P < .001). The aOR for birthweight was 0.65 per 1 kg increase (95% CI, 0.53-0.80; P < .001). The aOR for a family income of <$40,000 compared with ≥$150,000 was 3.50 (95% CI, 2.22-5.53; P < .001), and the aOR for family income between $40,000-$79,999 compared with ≥$150,000 was 1.88 (95% CI, 1.26-2.80; P = .002).

CONCLUSIONS

Screening positive on the ITC may identify children at risk for the double jeopardy of developmental delay and social disadvantage and allow clinicians to intervene through monitoring, referral, and resource navigation for both child development and social needs.

TRIAL REGISTRATION

Clinicaltrials.gov (NCT01869530).

Association of birthweight with diabetes, hypertension, and ischemic heart disease in young adulthood: a retrospective cohort study

Birthweight has been associated with diabetes in a reverse J-shape (highest risk at low birthweight and moderately high risk at high birthweight) and inversely associated with hypertension in adulthood with inconsistent evidence for cardiovascular disease. There is a lack of population-based studies examining the incidence of cardiometabolic outcomes in young adults born with low and high birthweights. To evaluate the association between birthweight and diabetes, hypertension, and ischemic heart disease (IHD) in young adulthood, we conducted a retrospective cohort study of 874,904 singletons born in Ontario, Canada, from 1994 to 2002, identified from population-based health administrative data. Separate Cox regression models examined birthweight in association with diabetes, hypertension, and IHD adjusting for confounders. Among adults 18-26 years, the diabetes incidence rate was 18.15 per 100,000 person-years, hypertension was 15.80 per 100,000 person-years, and IHD was 1.85 per 100,000 person-years. Adjusted hazard ratios (AHR) for the hazard of diabetes with low (<2500g) and high (>4000g), compared with normal (2500-4000g) birthweight, were 1.46 (95% CI 1.28, 1.68) and 1.09 (0.99, 1.21), respectively. AHR for hypertension with low and high birthweight were 1.34 (1.15, 1.56) and 0.86 (0.77, 0.97), respectively. AHR for IHD with low and high birthweight were 1.28 (0.80, 2.05) and 0.97 (0.71, 1.33), respectively. Overall, birthweight was associated with diabetes in young adults in a reverse J-shape and inversely with hypertension. There was insufficient evidence of an association with IHD. Further evidence is needed to understand the causal mechanisms between birthweight and cardiometabolic diseases in young adults.

Changes in sleep and the prevalence of probable insomnia in undergraduate university students over the course of the COVID-19 pandemic: findings from the U-Flourish cohort study

BACKGROUND

Sleep problems associated with poor mental health and academic outcomes may have been exacerbated by the COVID-19 pandemic.

AIMS

To describe sleep in undergraduate students during the COVID-19 pandemic.

METHOD

This longitudinal analysis included data from 9523 students over 4 years (2018-2022), associated with different pandemic phases. Students completed a biannual survey assessing risk factors, mental health symptoms and lifestyle, using validated measures. Sleep was assessed with the Sleep Condition Indicator (SCI-8). Propensity weights and multivariable log-binomial regressions were used to compare sleep in four successive first-year cohorts. Linear mixed-effects models were used to examine changes in sleep over academic semesters and years.

RESULTS

There was an overall decrease in average SCI-8 scores, indicating worsening sleep across academic years (average change -0.42 per year; P-trend < 0.001), and an increase in probable insomnia at university entry (range 18.1-29.7%; P-trend < 0.001) before and up to the peak of the pandemic. Sleep improved somewhat in autumn 2021, when restrictions loosened. Students commonly reported daytime sleep problems, including mood, energy, relationships (36-48%) and concentration, productivity, and daytime sleepiness (54-66%). There was a consistent pattern of worsening sleep over the academic year. Probable insomnia was associated with increased cannabis use and passive screen time, and reduced recreation and exercise.

CONCLUSIONS

Sleep difficulties are common and persistent in students, were amplified by the pandemic and worsen over the academic year. Given the importance of sleep for well-being and academic success, a preventive focus on sleep hygiene, healthy lifestyle and low-intensity sleep interventions seems justified.

Validation of Parent-reported Gestational Age Categories for Children Less Than 6 Years of Age

BACKGROUND

Preterm birth is an important outcome or exposure in epidemiologic research. When administrative data on measured gestational age is not available, parent-reported gestational age can be obtained from questionnaires, which is subject to potential bias. To our knowledge, few studies have assessed the validity of parent-reported gestational age categories, including commonly defined categories of preterm birth.

METHODS

We used linked data from primarily healthy children <6 years of age in TARGet Kids! in Toronto, Canada, and ICES administrative healthcare data from April 2011 to March 2020. We assessed the criterion validity of questionnaire-based parent-reported gestational age by calculating sensitivity and specificity for term (≥37 weeks), late preterm (34-36 weeks), and moderately preterm (32-33 weeks) gestational age categories, using administrative healthcare records of gestational age as the criterion standard. We conducted subgroup analyses for various parent and socioeconomic factors that may influence recall.

RESULTS

Of the 4684 participants, 97.3% correctly classified the gestational age category according to administrative healthcare data. Parent-reported gestational age sensitivity ranged from 83.7% to 98.5% and specificity ranged from 88.3% to 99.8%, depending on category. For each subgroup characteristic, sensitivity and specificity were all ≥70%. Lower educational attainment, lower family income, father reporting, ≥1 year since birth, ≥2 children, lower parent age, and reported gestational diabetes and/or hypertension were associated with slightly lower sensitivity and/or specificity.

CONCLUSIONS

In this linked cohort, parent-reported gestational age categories had high accuracy. Criterion validity varied minimally among some parent and socioeconomic factors. Our findings can inform future quantitative bias analyses.

Timing of introduction to solid food, eczema and wheezing in later childhood: a longitudinal cohort study

BACKGROUND

The timing of introduction to solid food has been associated with eczema and wheezing in childhood. Our aim was to determine whether differences persist within the recommended 4 to 6 month age range.

METHODS

A longitudinal cohort study with repeated measures was conducted among children from birth to 10 years of age who were participating in the TARGet Kids! practice based research network in Toronto, Canada. The primary exposure was the timing of introduction to infant cereal as the first solid food. The primary outcome was eczema and the secondary outcome was wheezing collected by parent report using the validated International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Multinomial generalized estimating equations were used and effect modification by family history of asthma and breastfeeding duration were explored.

RESULTS

Of the 7843 children included, the mean (standard deviation) age of introduction to infant cereal was 5.7 (1.9) months. There was evidence for family history of asthma and breastfeeding duration to be effect modifiers in the eczema (P = 0.04) and wheezing (P = 0.05) models. Introduction to infant cereal at 4 vs. 6 months of age was associated with higher odds of eczema (OR 1.62; 95% CI: 1.12, 2.35; P = 0.01) among children without a family history of asthma who were not breastfeeding when solid foods were introduced. Introduction to infant cereal at 4 vs. 6 months of age was associated with a higher odds of wheezing (OR 1.31; 95% CI: 1.13, 1.52; P < .001) among children without a family history of asthma who were breastfeeding when solid foods were introduced. There was little evidence of an association among the remaining strata for either outcome.

CONCLUSION

The findings of this study support recommendations to introduce solid food around 6 months of age.

New approaches and technical considerations in detecting outlier measurements and trajectories in longitudinal children growth data

BACKGROUND

Growth studies rely on longitudinal measurements, typically represented as trajectories. However, anthropometry is prone to errors that can generate outliers. While various methods are available for detecting outlier measurements, a gold standard has yet to be identified, and there is no established method for outlying trajectories. Thus, outlier types and their effects on growth pattern detection still need to be investigated. This work aimed to assess the performance of six methods at detecting different types of outliers, propose two novel methods for outlier trajectory detection and evaluate how outliers affect growth pattern detection.

METHODS

We included 393 healthy infants from The Applied Research Group for Kids (TARGet Kids!) cohort and 1651 children with severe malnutrition from the co-trimoxazole prophylaxis clinical trial. We injected outliers of three types and six intensities and applied four outlier detection methods for measurements (model-based and World Health Organization cut-offs-based) and two for trajectories. We also assessed growth pattern detection before and after outlier injection using time series clustering and latent class mixed models. Error type, intensity, and population affected method performance.

RESULTS

Model-based outlier detection methods performed best for measurements with precision between 5.72-99.89%, especially for low and moderate error intensities. The clustering-based outlier trajectory method had high precision of 14.93-99.12%. Combining methods improved the detection rate to 21.82% in outlier measurements. Finally, when comparing growth groups with and without outliers, the outliers were shown to alter group membership by 57.9 -79.04%.

CONCLUSIONS

World Health Organization cut-off-based techniques were shown to perform well in few very particular cases (extreme errors of high intensity), while model-based techniques performed well, especially for moderate errors of low intensity. Clustering-based outlier trajectory detection performed exceptionally well across all types and intensities of errors, indicating a potential strategic change in how outliers in growth data are viewed. Finally, the importance of detecting outliers was shown, given its impact on children growth studies, as demonstrated by comparing results of growth group detection.

Late preterm birth and growth trajectories during childhood: a linked retrospective cohort study

BACKGROUND

Evidence suggests that accelerated postnatal growth in children is detrimental for adult cardiovascular health. It is unclear whether children born late preterm (34-36 weeks) compared to full term (≥ 39 weeks), have different growth trajectories. Our objective was to evaluate the association between gestational age groups and growth trajectories of children born between 2006-2014 and followed to 2021 in Ontario, Canada.

METHODS

We conducted a retrospective cohort study of children from singleton births in TARGet Kids! primary care network with repeated measures of weight and height/length from birth to 14 years, who were linked to health administrative databases. Piecewise linear mixed models were used to model weight (kg/month) and height (cm/month) trajectories with knots at 3, 12, and 84 months. Analyses were conducted based on chronological age.

RESULTS

There were 4423 children included with a mean of 11 weight and height measures per child. The mean age at the last visit was 5.9 years (Standard Deviation: 3.1). Generally, the more preterm, the lower the mean value of weight and height until early adolescence. Differences in mean weight and height for very/moderate preterm and late preterm compared to full term were evident until 12 months of age. Weight trajectories were similar between children born late preterm and full term with small differences from 84-168 months (mean difference (MD) -0.04 kg/month, 95% CI -0.06, -0.03). Children born late preterm had faster height gain from 0-3 months (MD 0.70 cm/month, 95% CI 0.42, 0.97) and 3-12 months (MD 0.17 cm/month, 95% CI 0.11, 0.22).

CONCLUSIONS

Compared to full term, children born late preterm had lower average weight and height from birth to 14 years, had a slightly slower rate of weight gain after 84 months and a faster rate of height gain from 0-12 months. Follow-up is needed to determine if growth differences are associated with long-term disease risk.

A novel systematic pipeline for increased predictability and explainability of growth patterns in children using trajectory features

OBJECTIVE

Longitudinal patterns of growth in early childhood are associated with health conditions throughout life. Knowledge of such patterns and the ability to predict them can lead to better prevention and improved health promotion in adulthood. However, growth analyses are characterized by significant variability, and pattern detection is affected by the method applied. Moreover, pattern labelling is typically performed based on ad hoc methods, such as visualizations or clinical experience. Here, we propose a novel pipeline using features extracted from growth trajectories using mathematical, statistical and machine-learning approaches to predict growth patterns and label them in a systematic and unequivocal manner.

METHODS

We extracted mathematical and clinical features from 9577 children growth trajectories embedded with machine-learning predictions of the growth patterns. We experimented with two sets of features (CAnonical Time-series Characteristics and trajectory features specific to growth), developmental periods and six machine-learning classifiers. Clinical experts provided labels for the detected patterns and decision rules were created to associate the features with the labelled patterns. The predictive capacity of the extracted features was validated on two heterogenous populations (The Applied Research Group for Kids and the 2004 Pelotas Birth Cohort, based in Canada and Brazil, respectively).

RESULTS

Features predictive ability measured by accuracy and F1 score was ≥ 80% and ≥ 0.76 respectively in both cohorts. A small number of features (n = 74) was sufficient to distinguish between growth patterns in both cohorts. Slope, intercept of the trajectory, age at peak value, start value and change of the growth measure were among the top identified features.

CONCLUSION

Growth features can be reliably used as predictors of growth patterns and provide an unbiased understanding of growth patterns. They can be used as tool to reduce the effort to repeat analysis and variability concerning anthropometric measures, time points and analytical methods, in the context of the same or similar populations.

Validation of a parent proxy-reported beverage screener compared to a 24-hour dietary recall for the measurement of sugar-containing beverage intake among young children

Measures that can provide reasonably accurate estimates of sugar-containing beverage (SCB) intake among children are needed. The primary objective of this study was to evaluate the relative validity of a short beverage screener (Nutrition and Health Questionnaire, NHQ) compared to a 24-hour recall (Automated Self-Administered 24-h (ASA24) Dietary Assessment Tool-Canada) for assessing parent proxy-reported daily SCB intake among children aged 4-14 years from the TARGet Kids! research network in Toronto, Canada. Children for whom a NHQ completed between March 2018 and June 2019 and an ASA24 completed within one year were included. A total of 471 parents who completed the NHQ beverage screener were also asked to complete the ASA24. One-hundred sixty-three completed the ASA24 and of this group, 109 were analyzed. Estimates of daily intake of 100% juices, sweetened drinks and soda, and total SCBs from the two measures were compared. The mean difference in beverage intake, Spearman correlations, and Bland-Altman plots were estimated for continuous measures. The kappa coefficient, sensitivity, and specificity were calculated for dichotomous measures of any daily intake versus none. The mean difference in total SCB intake between the NHQ and ASA24 was 0.14 cups/day (95% CI 0.01, 0.29) and the correlation was 0.43 (95% CI 0.26, 0.57). Sensitivity and specificity for any daily SCB intake were 0.63 and 0.76, respectively. Overall, parent proxy-reporting of children's total SCB intake from a beverage screener can provide reasonable estimates of SCB intake when detailed dietary assessment is not feasible.

Effect of plant milk consumption on childhood growth: protocol for a systematic review

INTRODUCTION

There has been considerable debate about whether plant milks can support the nutritional requirements of growing children. The proposed systematic review aims to assess the evidence on the relationship between plant milk consumption and growth and nutritional status in childhood.

METHODS AND ANALYSIS

Ovid MEDLINE ALL (1946-present), Ovid EMBASE Classic (1947-present), CINAHL Complete (Cumulative Index to Nursing and Allied Health Literature), Scopus, the Cochrane Library and grey literature will be searched comprehensively (from 2000 to present; English language) to find studies that describe the association between plant milk consumption and growth or nutrition in children 1-18 years of age. Two reviewers will identify eligible articles, extract data and assess the risk of bias in individual studies. If a meta-analyses is not conducted, the evidence will be synthesised narratively and the overall certainty of evidence will be rated using the Grading of Recommendations Assessment, Development and Evaluation approach.

ETHICS AND DISSEMINATION

Ethical approval is not required for this study since no data will be collected. Results of the systematic review will be published in a peer-reviewed journal. Findings from this study may be useful in informing future evidence-based recommendations about plant milk consumption in children.

PROSPERO REGISTRATION NUMBER

CRD42022367269.

Statistical haemoglobin thresholds to define anaemia across the lifecycle

Detection of anaemia is critical for clinical medicine and public health. Current WHO values that define anaemia are statistical thresholds (5 ^th centile) set over 50 years ago, and are presently <110g/L in children 6-59 months, <115g/L in children 5-11 years, <110g/L in pregnant women, <120g/L in children 12-14 years of age, <120g/L in non-pregnant women, and <130g/L in men. Haemoglobin is sensitive to iron and other nutrient deficiencies, medical illness and inflammation, and is impacted by genetic conditions; thus, careful exclusion of these conditions is crucial to obtain a healthy reference population. We identified data sources from which sufficient clinical and laboratory information was available to determine an apparently healthy reference sample. Individuals were excluded if they had any clinical or biochemical evidence of a condition that may diminish haemoglobin concentration. Discrete 5 ^th centiles were estimated along with two-sided 90% confidence intervals and estimates combined using a fixed-effect approach. Estimates for the 5 ^th centile of the healthy reference population in children were similar between sexes. Thresholds in children 6-23 months were 104.4g/L [90% CI 103.5, 105.3]; in children 24-59 months were 110.2g/L [109.5, 110.9]; and in children 5-11 years were 114.1g/L [113.2, 115.0]. Thresholds diverged by sex in adolescents and adults. In females and males 12-17 years, thresholds were 122.2g/L [121.3, 123.1] and 128.2 [126.4, 130.0], respectively. In adults 18-65 years, thresholds were 119.7g/L [119.1, 120.3] in non-pregnant females and 134.9g/L [134.2, 135.6] in males. Limited analyses indicated 5 ^th centiles in first-trimester pregnancy of 110.3g/L [109.5, 111.0] and 105.9g/L [104.0, 107.7] in the second trimester. All thresholds were robust to variations in definitions and analysis models. Using multiple datasets comprising Asian, African, and European ancestries, we did not identify novel high prevalence genetic variants that influence haemoglobin concentration, other than variants in genes known to cause important clinical disease, suggesting non-clinical genetic factors do not influence the 5 ^th centile between ancestries. Our results directly inform WHO guideline development and provide a platform for global harmonisation of laboratory, clinical and public health haemoglobin thresholds.

Breastfeeding support provided by lactation consultants in high-income countries for improved breastfeeding rates, self-efficacy, and infant growth: a systematic review and meta-analysis protocol

BACKGROUND

It is well established that breast milk offers numerous health benefits for mother and child. Mothers are recommended to exclusively breastfeed their child until 6 months of age, with continued breastfeeding up to 1-2 years of age or beyond. Yet, these recommendations are met less than half of the time in high-income countries. Lactation consultants specialize in supporting mothers with breastfeeding and are a promising approach to improving breastfeeding rates. For lactation consultant interventions to be implemented widely as part of public health policy, a better understanding of their effect on breastfeeding rates and important health outcomes is needed.

METHODS

The overall aim of this systematic review is to evaluate the effect of lactation consultant interventions provided to women, compared to usual care, on breastfeeding rates (primary outcome), maternal breastfeeding self-efficacy, and infant growth. A search strategy has been developed to identify randomized controlled trials published in any language between 1985 and April 2023 in CENTRAL, MEDLINE, EMBASE, CINAHL, Scopus, and Web of Science. We will also perform a search of the grey literature and reference lists of relevant studies and reviews. Two reviewers will independently extract data on study design, baseline characteristics, details of the interventions employed, and primary and secondary outcomes using a pre-piloted standardized data extraction form. Risk of bias and quality of evidence assessment will be done independently and in duplicate using the Cochrane Risk of Bias tool and GRADE approach, respectively. Where possible, meta-analysis using random-effects models will be performed, otherwise a qualitative summary will be provided. We will adhere to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

DISCUSSION

This review will fill an important gap in the lactation support literature. The findings will be of importance to policymakers who seek to implement interventions to improve breastfeeding rates.

TRIAL REGISTRATION

This review has been registered in the PROSPERO database (ID: CRD42022326597).

Centre-based childcare in early childhood and growth in later childhood: a prospective cohort study

BACKGROUND

Attending government-regulated centre-based childcare may influence important health behaviours including dietary quality, physical activity and routines related to child growth. However, the relationship between centre-based childcare and childhood obesity remains unclear.

OBJECTIVES

The primary objective was to evaluate the association between centre-based childcare attendance in early childhood and body mass index z-score (zBMI) in later childhood. Secondary objectives included exploring whether family income, child sex, or non-centre-based setting modified these relationships.

METHODS

A prospective cohort study of children aged 1 to 10 years who participated in the TARGet Kids! cohort was conducted. Linear mixed-effect modelling was used to evaluate the relationship between centre-based childcare attendance (in hours/week) compared to non-centre-based childcare between 1-4 years of age and zBMI between 4 and 10 years of age. Generalised estimating equation modelling was used to explore weight status categories. Models were adjusted for confounders and effect modification was explored.

RESULTS

A total of 3503 children were included. Children who attended centre-based childcare full-time (40 h/week) had 0.11 (95% CI: -0.19, -0.03; p = 0.01) lower zBMI at 4 and 7 years of age and lower odds of overweight and obesity at 4 years (OR 0.78; 95% CI: 0.62, 0.97; p = 0.03), but no evidence of an association was found at 10 years of age. Children from families with income < $50,000CDN who attended centre-based childcare full-time had 0.32 (95% CI: -0.50, -0.14; p = 0.001) lower zBMI and lower odds of overweight and obesity (OR 0.52; 95% CI: 0.28, 0.99; p = 0.05) at 10 years of age.

CONCLUSIONS

Attending centre-based childcare in early childhood was associated with a lower zBMI and odds of overweight and obesity in later childhood. These associations were stronger for children from lower income families. Centre-based childcare may be an early intervention for the prevention of childhood obesity.

CLINICAL TRIAL

Clinical Trial Registry Number: NCT01869530 (clinicaltrials.gov).

Maternal BMI in the preconception period, and association with child zBMI growth rates

BACKGROUND

Elevated body mass index (BMI) and rapid growth in early childhood are important predictors of obesity risk. The association between maternal preconception BMI and child growth rates is unclear.

OBJECTIVES

To assess the association between measured maternal preconception BMI and child age- and sex- standardized WHO BMI z-score (zBMI) growth rates and mean zBMI, in children aged 0-10 years old.

METHODS

A longitudinal cohort study was conducted with children (n = 499) enrolled in The Applied Research Group for Kids (TARGet Kids!) primary care practice-based research cohort. Maternal BMI was measured during the preconception period, defined as the 2 years prior to pregnancy. Repeated measures of child weight and height were obtained between 0 and 10 years of age. Linear mixed models were used to evaluate the association between maternal BMI and child zBMI growth rates and mean zBMI.

RESULTS

Maternal preconception BMI was associated with child zBMI growth rate during some growth periods, with the strongest association from age 0 to 4 months; a 5 kg/m2 higher maternal BMI was associated with 0.031 zBMI SD unit/mo higher growth rate (p = 0.004), and 0.186 SD unit higher mean child zBMI (p = 0.0002).

CONCLUSIONS

Maternal preconception BMI was associated with growth rate and mean zBMI in early childhood. The preconception period may be an important target for health interventions to promote healthy child growth rate and weight outcomes.

Changes in Pediatric Movement Behaviors During the COVID-19 Pandemic by Stages of Lockdown in Ontario, Canada: A Longitudinal Cohort Study

BACKGROUND

Children's movement behaviors have been affected by the COVID-19 pandemic; however, little is known regarding movement behavior patterns over time by government-issued lockdowns. Our primary objective was to evaluate how children's movement behaviors changed by stages of lockdown/reopening in Ontario, Canada, from 2020 to 2021.

METHODS

A longitudinal cohort study with repeated measures of exposure and outcomes was conducted. The exposure variables were dates from before and during COVID-19 when child movement behavior questionnaires were completed. Lockdown/reopening dates were included as knot locations in the spline model. The outcomes were daily screen, physical activity, outdoor, and sleep time.

RESULTS

A total of 589 children with 4805 observations were included (53.1% boys, 5.9 [2.6] y). On average, screen time increased during the first and second lockdowns and decreased during the second reopening. Physical activity and outdoor time increased during the first lockdown, decreased during the first reopening, and increased during the second reopening. Younger children (<5 y) had greater increases in screen time and lower increases in physical activity and outdoor time than older children (≥5 y).

CONCLUSIONS

Policy makers should consider the impact of lockdowns on child movement behaviors, especially in younger children.

Predictive Validity of the Infant Toddler Checklist in Primary Care at the 18-month Visit and School Readiness at 4 to 6 Years

OBJECTIVE

The American Academy of Pediatrics recommends developmental surveillance and screening in early childhood in primary care. The 18-month visit may be an ideal time for identification of children with delays in language and communication, or symptoms of autism spectrum disorder (ASD). Little is known about the predictive validity of developmental screening tools administered at 18 months. Our objective was to examine the predictive validity of the Infant Toddler Checklist (ITC) at the 18-month health supervision visit, using school readiness at kindergarten age as the criterion measure.

METHODS

We designed a prospective cohort study, recruiting in primary care in Toronto, Canada. Parents completed the ITC at the 18-month visit. Teachers completed the Early Development Instrument (EDI) when the children were in Kindergarten, age 4-6 years. We calculated screening test properties with 95% confidence intervals (CIs). We used multivariable logistic and linear regression analyses adjusted for important covariates.

RESULTS

Of 293 children (mean age 18 months), 30 (10.2%) had a positive ITC including: concern for speech delay (n = 11, 3.8%), concern for other communication delay (n = 13, 4.4%), and concern for both (n = 6, 2.0%). At follow-up (mean age 5 years), 54 (18.4%) had overall EDI vulnerability, 19 (6.5%) had vulnerability on the 2 EDI communication domains. The ITC sensitivity ranged from 11% to 32%, specificity from 91% to 96%, false positive rates from 4% to 9%, PPV from 16% to 35%, NPV from 83% to 95%. A positive ITC screen and ITC concern for speech delay were associated with lower scores in EDI communication skills and general knowledge (β = -1.08; 95% CI: -2.10, -0.17; β = -2.35; 95% CI: -3.63, -1.32) and EDI language and cognitive development (β = -0.62; 95% CI: -1.25, -0.18; β = -1.22; 95% CI: -2.11, -0.58).

CONCLUSIONS

The ITC demonstrated high specificity suggesting that most children with a negative ITC screen will demonstrate school readiness at 4-6 years, and low false positive rates, minimizing over-diagnosis. The ITC had low sensitivity highlighting the importance of ongoing developmental surveillance and screening.

Factors associated with research participation in a large primary care practice-based pediatric cohort: Results from the TARGet Kids! longitudinal cohort study

BACKGROUND

All longitudinal cohort studies strive for high participant retention, although attrition is common. Understanding determinants of attrition is important to inform and develop targeted strategies to improve study participation. We aimed to identify factors associated with research participation in a large children's primary care cohort study.

METHODS

In this longitudinal cohort study between 2008 and 2020, all children who participated in the Applied Research Group for Kids (TARGet Kids!) were included. TARGet Kids! is a large primary care practice-based pediatric research network in Canada with ongoing data collection at well-child visits. Several sociodemographic, health, and study design factors were examined for their associations with research participation. The primary outcome was attendance of eligible research follow-up visits. The secondary outcome was time to withdrawal from the TARGet Kids! study. Generalized linear mixed effects models and Cox proportional hazard models were fitted. We have engaged parent partners in all stages of this study.

RESULTS

A total 10,412 children with 62,655 total eligible research follow-up visits were included. Mean age at enrolment was 22 months, 52% were male, and 52% had mothers of European ethnicity. 68.4% of the participants attended at least 1 research follow-up visit. Since 2008, 6.4% of the participants have submitted a withdrawal request. Key factors associated with research participation included child age, ethnicity, maternal age, maternal education level, family income, parental employment, child diagnosis of chronic health conditions, certain study sites, and missingness in questionnaire data.

CONCLUSIONS

Socioeconomic status, demographic factors, chronic conditions, and missingness in questionnaire data were associated with research participation in this large primary care practice-based cohort study of children. Results from this analysis and input from our parent partners suggested that retention strategies could include continued parent engagement, creating brand identity and communication tools, using multiple languages and avoiding redundancy in the questionnaires.

Sleep Duration and Internalizing Symptoms in Children

OBJECTIVE

Emotional problems such as anxiety and low mood have been associated with sleep problems in children. The study's objectives were to 1) assess the association between sleep duration and internalizing symptoms (anxiety and low mood) in children aged 5-12 years (y), and 2) evaluate whether insufficient sleep according to the National Sleep Foundation (NSF) guidelines is associated with internalizing symptoms.

METHODS

A cross-sectional study of N =796 children aged 5-12y, recruited from primary care physicians' offices in Toronto, Canada was conducted through the TARGet Kids! research network. Using linear regression, we investigated 1) the cross-sectional association between parent reported 24-hour sleep duration (hours) and parent reported symptoms using the Strengths and Difficulties Questionnaire (SDQ), controlling for child age, sex, family income, maternal education, family composition, and standardized body-mass index (zBMI). The analysis was repeated using insufficient sleep per NSF guideline as the independent variable.

RESULTS

Sleep duration was inversely associated with internalizing symptoms, B estimate = -0.33 (95%CI -0.57, -0.07), p=0.012. Twenty-eight (14%) children aged 5 y, and 36 (6%) of those aged 6-12y, experienced insufficient sleep. There was a trend toward association between insufficient sleep and internalizing symptoms, B estimate = 0.64 (-0.09, 1.38), p=0.086.

CONCLUSION

The relationship between insufficient sleep and internalizing symptoms among children requires further elucidation. Children who show internalizing symptoms may benefit from interventions supporting sleep.

Body Weight at Age Four Years and Readiness to Start School: A Prospective Cohort Study

Background: Adolescents with obesity have lower academic performance, but little is known about the association between body weight in early childhood and school readiness. The objective was to examine the association between age- and sex-standardized body mass index (zBMI) and body weight status and school readiness in young children. Methods: A prospective cohort study in Toronto, Canada, was conducted in young children enrolled in TARGet Kids!. Children's weight and height were measured before the start of kindergarten. Children's school readiness was measured by the Early Development Instrument (EDI), a validated teacher-completed instrument that assesses children's skills and behaviors in five developmental domains in kindergarten. Generalized estimating equations, adjusted for relevant confounders, were used in the analysis. Results: The study included 1015 children (1217 observations): 52% were male and mean age at zBMI was 4.2 years [50 months (SD 12.1)] and school readiness was 5.2 years [62.7 months (SD 6.9)]. There was no evidence found that zBMI was associated with school readiness. However, in a post hoc analysis, being classified as overweight or with obesity in kindergarten was associated with twofold higher odds of vulnerability in school readiness and a lower social competence score compared with their normal weight peers. Conclusions: Being classified as overweight or with obesity was associated with poor school readiness in year 2 of kindergarten. Early interventions to promote healthy growth before school entry may help promote development and school readiness in young children. www.clinicaltrials.gov (NCT01869530).

Underweight in the First 2 Years of Life and Growth in Later Childhood

IMPORTANCE

Few studies have examined the association between underweight in the first 2 years and growth in later childhood in high-income countries.

OBJECTIVE

To evaluate the associations of underweight in the first 2 years of life with body mass index (calculated as weight in kilograms divided by height in meters squared) z score (zBMI), weight-for-age z score (WAZ), and height-for-age z score (HAZ) from ages 2 to 10 years.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study was conducted between February 2008 to September 2020 in The Applied Research Group for Kids! practice-based research network in Toronto, Canada. Participants included healthy children aged 0 to 10 years. Data were analyzed from October 2020 to December 2021.

EXPOSURES

Underweight (ie, zBMI less than -2, per the World Health Organization) in the first 2 years of life.

MAIN OUTCOMES AND MEASURES

The primary outcome was zBMI from ages 2 to 10 years. Linear mixed-effects models were used to account for multiple growth measures over time.

RESULTS

A total of 5803 children were included in the primary analysis. At baseline, the mean (SD) age was 4.07 (5.62) months, 2982 (52.2%) were boys, and 550 children (9.5%) were underweight. Underweight in the first 2 years was associated with lower zBMI (difference, -0.39 [95% CI, -0.48 to -0.31]) at 10 years and lower HAZ (difference, -0.24 [95% CI, -0.34 to -0.14]) at age 2 years. Stratified by sex, at age 10 years, girls and boys with underweight in the first 2 years both had lower zBMI (girls: difference, -0.47 [95% CI, -0.59 to -0.34]; boys: difference, -0.32 [95% CI, -0.44 to -0.20]). At age 10 years, children with underweight and a lower zBMI growth rate in the first 2 years had lower zBMI (difference, -0.64 [95% CI, -0.77 to -0.53) and HAZ (difference, -0.12 [-0.24 to -0.01]), while children with underweight and a higher zBMI growth rate in the first 2 years had similar zBMI (difference, -0.11 [95% CI, -0.22 to 0.001]) and higher HAZ (difference, 0.16 [95% CI, 0.05 to 0.27]) compared with children who did not have underweight in the first 2 years.

CONCLUSIONS AND RELEVANCE

In this prospective cohort study, children with underweight in the first 2 years of life had lower zBMI and HAZ in later childhood. These associations were attenuated among children with a higher growth rate in the first 2 years.

Vegetarian Diet, Growth, and Nutrition in Early Childhood: A Longitudinal Cohort Study

OBJECTIVES

The primary objective of this study was to examine the relationships between vegetarian diet and growth, micronutrient stores, and serum lipids among healthy children. Secondary objectives included exploring whether cow's milk consumption or age modified these relationships.

METHODS

A longitudinal cohort study of children aged 6 months to 8 years who participated in the TARGet Kids! cohort study. Linear mixed-effect modeling was used to evaluate the relationships between vegetarian diet and BMI z-score (zBMI), height-for-age z-score, serum ferritin, 25-hydroxyvitamin D, and serum lipids. Generalized estimating equation modeling was used to explore weight status categories. Possible effect modification by age and cow's milk consumption was examined.

RESULTS

A total of 8907 children, including 248 vegetarian at baseline, participated. Mean age at baseline was 2.2 years (SD 1.5). There was no evidence of an association between vegetarian diet and zBMI, height-for-age z-score, serum ferritin, 25-hydroxyvitamin D, or serum lipids. Children with vegetarian diet had higher odds of underweight (zBMI <-2) (odds ratio 1.87, 95% confidence interval 1.19 to 2.96; P = .007) but no association with overweight or obesity was found. Cow's milk consumption was associated with higher nonhigh-density lipoprotein cholesterol (P = .03), total cholesterol (P = .04), and low-density lipoprotein cholesterol (P = .02) among children with vegetarian diet. However, children with and without vegetarian diet who consumed the recommended 2 cups of cow's milk per day had similar serum lipids.

CONCLUSIONS

Evidence of clinically meaningful differences in growth or biochemical measures of nutrition for children with vegetarian diet was not found. However, vegetarian diet was associated with higher odds of underweight.

Children's screen use and school readiness at 4-6 years: prospective cohort study

Background

The primary aim of this study was to determine if screen use in early childhood is associated with overall vulnerability in school readiness at ages 4 to 6 years, as measured by the Early Development Instrument (EDI). Secondary aims were to: (1) determine if screen use was associated with individual EDI domains scores, and (2) examine the association between screen use and EDI domains scores among a subgroup of high screen users.

Methods

This prospective cohort study was carried out using data from young children participating in a large primary care practice-based research network in Canada. Logistic regression analyses were run to investigate the association between screen use and overall vulnerability in school readiness. Separate linear regression models examined the relationships between children’s daily screen use and each separate continuous EDI domain.

Results

A total of 876 Canadian participants participated in this study. Adjusted logistic regression revealed an association between increased screen use and increased vulnerability in school readiness (p = 0.05). Results from adjusted linear regression demonstrated an association between higher screen use and reduced language and cognitive development domain scores (p = 0.004). Among high screen users, adjusted linear regression models revealed associations between increased screen use and reduced language and cognitive development (p = 0.004) and communication skills and general knowledge domain scores (p = 0.042).

Conclusions

Screen use in early childhood is associated with increased vulnerability in developmental readiness for school, with increased risk for poorer language and cognitive development in kindergarten, especially among high users.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-12629-8.

Understanding income-related differences in distribution of child growth, behaviour and development using a cross-sectional sample of a clinical cohort study

OBJECTIVES

Children from low-income households are at an increased risk of social, behavioural and physical health problems. Prior studies have generally relied on dichotomous outcome measures. However, inequities may exist along the range of outcome distribution. Our objective was to examine differences in distribution of three child health outcomes by income categories (high vs low): body mass index (BMI), behaviour difficulties and development.

DESIGN AND SETTING

This was a cross-sectional study using data from a primary care-based research network with sites in three Canadian cities, and 15 practices enrolling participants.

PARTICIPANTS, INDEPENDENT VARIABLE AND OUTCOMES

The independent variable was annual household income, dichotomised at the median income for Toronto (<$C80 000 or ≥$C80 000). Outcomes were: (1) growth (BMI z-score (zBMI) at 5 years, 1628 participants); (2) behaviour (Strengths and Difficulties Questionnaire (SDQ) at 3-5 years, 649 participants); (3) development (Infant Toddler Checklist (ITC) at 18 months, 1405 participants). We used distributional decomposition to compare distributions of these outcomes for each income group, and then to construct a counterfactual distribution that describes the hypothetical distribution of the low-income group with the predictor profile of the higher-income group.

RESULTS

We included data from 1628 (zBMI), 649 (SDQ) and 1405 (ITC) children. Children with lower family income had a higher risk distribution for all outcomes. For all outcomes, thecounterfactual distribution, which represented the distribution of children with lower-income who were assigned the predictor profile of the higher-income group, was more favourable than their observed distributions.

CONCLUSION

Comparing the distributions of child health outcomes and understanding different risk profiles for children from higher-income and lower-income groups can offer a deeper understanding of inequities in child health outcomes. These methods may offer an approach that can be implemented in larger datasets to inform future interventions.

Association Between Physical Activity, Screen Time and Sleep, and School Readiness in Canadian Children Aged 4 to 6 Years

OBJECTIVE

School readiness is strongly associated with a child's future school success and well-being. The primary objective of this study was to determine whether meeting 24-hour movement guidelines (national physical activity, sedentary behaviors, and sleep recommendations) was associated with school readiness measured with mean scores in each of the 5 developmental domains of the Early Development Instrument (EDI) in Canadian children aged 4 to 6 years. Secondary objectives include examining the following: (1) the association between meeting 24-hour movement guidelines and overall vulnerability in school readiness and (2) the association between meeting individual physical activity, screen use and sleep recommendations, and overall school readiness.

METHODS

A prospective cohort study was performed using data from children (aged 4-6 years) who participated in a large-scale primary care practice-based research network.

RESULTS

Of the 739 participants (aged 5.9 + 0.12 years) in this prospective cohort study, 18.2% met the 24-Hour Movement Guidelines. Linear regression models (adjusted for child/family demographic characteristics, number of siblings, immigration status, and annual household income) revealed no evidence of an association between meeting all 24-hour movement guidelines and any of the 5 domains of the EDI (p > 0.05). Adjusted linear regression models revealed evidence of an association between meeting screen use guidelines and the "language and cognitive development" (β = 0.16, p = 0.004) domain, and for the sleep guideline, there was a statistically significant association with the "physical health and well-being" (β = 0.23, p = 0.001), the "language and cognitive development" (β = 0.10, p = 0.003), and the "communication skills and general knowledge" (β = 0.18, p < 0.001) domain.

CONCLUSION

Early lifestyle interventions targeting screen use and sleep may be beneficial for improving a child's readiness for school.

Delay in childhood vaccinations during the COVID-19 pandemic

OBJECTIVES

In many jurisdictions, routine medical care was reduced in response to the COVID-19 pandemic. The objective of this study was to determine whether the frequency of on-time routine childhood vaccinations among children age 0-2 years was lower following the COVID-19 declaration of emergency in Ontario, Canada, on March 17, 2020, compared to prior to the pandemic.

METHODS

We conducted a longitudinal cohort study of healthy children aged 0-2 years participating in the TARGet Kids! primary care research network in Toronto, Canada. A logistic mixed effects regression model was used to determine odds ratios (ORs) for delayed vaccination (> 30 days vs. ≤ 30 days from the recommended date) before and after the COVID-19 declaration of emergency, adjusted for confounding variables. A Cox proportional hazards model was used to explore the relationship between the declaration of emergency and time to vaccination.

RESULTS

Among 1277 children, the proportion of on-time vaccinations was 81.8% prior to the COVID-19 declaration of emergency and 62.1% after (p < 0.001). The odds of delayed vaccination increased (odds ratio = 3.77, 95% CI: 2.86-4.96), and the hazard of administration of recommended vaccinations decreased after the declaration of emergency (hazard ratio = 0.75, 95% CI: 0.60-0.92). The median vaccination delay time was 5 days (95% CI: 4-5 days) prior to the declaration of emergency and 17 days (95% CI: 12-22 days) after.

CONCLUSION

The frequency of on-time routine childhood vaccinations was lower during the first wave of the COVID-19 pandemic. Sustained delays in routine vaccinations may lead to an increase in rates of vaccine-preventable diseases.

Nutritional Risk in Early Childhood and School Readiness

BACKGROUND

Nutrition in early childhood is important for healthy growth and development. Achieving school readiness is considered one of the most important developmental milestones for young children.

OBJECTIVES

The purpose of this study is to determine if nutritional risk in early childhood is associated with school readiness in kindergarten.

METHODS

A prospective cohort study was conducted through The Applied Research Group for Kids (TARGet Kids!) primary care research network in Toronto, Canada, 2015-2020. Nutritional risk was measured (18 mo to 5 y) using validated parent-completed questionnaires called Nutrition Screening for Toddlers and Preschoolers (NutriSTEP). High nutritional risk was categorized as scores ≥21. School readiness was measured using the validated teacher-completed Early Developmental Instrument (EDI), which measures 5 developmental domains in kindergarten (2 y of schooling, ages 4-6 y, before they enter grade 1). Vulnerability indicates scores lower than a population-based cutoff at the 10th percentile on at least 1 domain. Multiple logistic and linear regression models were conducted adjusting for relevant confounders.

RESULTS

The study included 896 children: 53% were male, 9% had high nutritional risk, and 17% were vulnerable on the EDI. A 1-SD increase in NutriSTEP total score was associated with 1.54 times increased odds of being vulnerable on the EDI among children in year 2 of kindergarten (P = 0.001). High nutritional risk cutoff was associated with 4.28 times increased odds of being vulnerable on the EDI among children in year 2 of kindergarten (P < 0.001). NutriSTEP total score and high nutritional risk were associated with lower scores on all 5 EDI domains, with the strongest association observed for the domains of language and cognitive development and communication skills and general knowledge.

CONCLUSIONS

Higher nutritional risk in early childhood is associated with lower school readiness in year 2 of kindergarten. Nutritional interventions early in life may offer opportunities to enhance school readiness. This trial was registered www.clinicaltrials.gov as NCT01869530.

Screen Use and Mental Health Symptoms in Canadian Children and Youth During the COVID-19 Pandemic

IMPORTANCE

Longitudinal research on specific forms of electronic screen use and mental health symptoms in children and youth during COVID-19 is minimal. Understanding the association may help develop policies and interventions targeting specific screen activities to promote healthful screen use and mental health in children and youth.

OBJECTIVE

To determine whether specific forms of screen use (television [TV] or digital media, video games, electronic learning, and video-chatting time) were associated with symptoms of depression, anxiety, conduct problems, irritability, hyperactivity, and inattention in children and youth during COVID-19.

DESIGN, SETTING, AND PARTICIPANTS

A longitudinal cohort study with repeated measures of exposures and outcomes was conducted in children and youth aged 2 to 18 years in Ontario, Canada, between May 2020 and April 2021 across 4 cohorts of children or youth: 2 community cohorts and 2 clinically referred cohorts. Parents were asked to complete repeated questionnaires about their children's health behaviors and mental health symptoms during COVID-19.

MAIN OUTCOMES AND MEASURES

The exposure variables were children's daily TV or digital media time, video game time, electronic-learning time, and video-chatting time. The mental health outcomes were parent-reported symptoms of child depression, anxiety, conduct problems and irritability, and hyperactivity/inattention using validated standardized tools.

RESULTS

This study included 2026 children with 6648 observations. In younger children (mean [SD] age, 5.9 [2.5] years; 275 male participants [51.7%]), higher TV or digital media time was associated with higher levels of conduct problems (age 2-4 years: β, 0.22 [95% CI, 0.10-0.35]; P < .001; age ≥4 years: β, 0.07 [95% CI, 0.02-0.11]; P = .007) and hyperactivity/inattention (β, 0.07 [95% CI, 0.006-0.14]; P = .04). In older children and youth (mean [SD] age, 11.3 [3.3] years; 844 male participants [56.5%]), higher levels of TV or digital media time were associated with higher levels of depression, anxiety, and inattention; higher levels of video game time were associated with higher levels of depression, irritability, inattention, and hyperactivity. Higher levels of electronic learning time were associated with higher levels of depression and anxiety.

CONCLUSIONS AND RELEVANCE

In this cohort study, higher levels of screen use were associated poor mental health of children and youth during the COVID-19 pandemic. These findings suggest that policy intervention as well as evidence-informed social supports are needed to promote healthful screen use and mental health in children and youth during the pandemic and beyond.

Association Between Atopic Dermatitis and Height, Body Mass Index, and Weight in Children

Importance

Atopic dermatitis may be associated with short stature and obesity in children, but most previous studies have been either small or cross-sectional.

Objective

To evaluate the association between atopic dermatitis and height, body mass index (BMI; calculated as weight in kilograms divided by height in meters squared), and weight throughout childhood.

Design, Setting, and Participants

TARGet Kids! (The Applied Research Group for Kids) is an ongoing prospective longitudinal cohort study that collects data at routine physician visits throughout childhood. In this cohort, children aged 5 or younger were followed up into adolescence at regular physician visits at general pediatric and family practices in Toronto, Canada, from June 2008 to February 2021.

Exposure

Parental report of atopic dermatitis.

Main Outcomes and Measures

Primary outcomes were length-for-age and BMI-for-age z scores. The secondary outcome was weight-for-age z score. Linear mixed effects models were used to estimate associations between atopic dermatitis and each outcome. In secondary analyses, interaction terms were included between atopic dermatitis and age.

Results

A total of 10 611 children were included in the analysis, with mean (SD) baseline age of 23 (20) months; 5070 (47.8%) participants were female. Participants were followed for a median (range) of 28.5 (0.0-158.0) months. A total of 1834 (17.3%) children had atopic dermatitis during follow-up. Atopic dermatitis was associated with lower length-for-age z score (-0.13; 95% CI, -0.17 to -0.09; P < .001), higher BMI z score (0.05; 95% CI, 0.01 to 0.09; P = .008), and lower weight-for-age z score (-0.07; 95% CI, -0.10 to -0.04; P < .001) compared with children without atopic dermatitis. The associations between atopic dermatitis and height and BMI changed with age, diminishing by age 14 years and 5.5 years, respectively. Based on World Health Organization growth tables, children with atopic dermatitis were on average 0.5 cm shorter with 0.2 more BMI units at age 2 years and 0.6 cm shorter with no difference in BMI at age 5 years than children without atopic dermatitis after adjusting for covariates. There was no evidence of interaction between atopic dermatitis and age with respect to weight.

Conclusions and Relevance

In this cohort study, atopic dermatitis was associated with shorter stature, higher BMI, and lower weight in early childhood, but these associations were small and, for height and BMI, attenuated with age and resolved by adolescence.

Income and neighbourhood deprivation in relation to obesity in urban dwelling children 0-12 years of age: a cross-sectional study from 2013 to 2019

BACKGROUND

Childhood obesity is a major public health concern. This study evaluated the independent and joint associations of family-level income, neighbourhood-level income and neighbourhood deprivation, in relation to child obesity.

METHODS

A cross-sectional study was conducted in children ≤12 years of age from TARGet Kids! primary care network (Greater Toronto Area, 2013-2019). Parent-reported family income was compared with median neighbourhood income and neighbourhood deprivation measured using the Ontario Marginalization Index. Children's height and weight were measured and body mass index (BMI) z-scores (zBMI) were calculated. ORs and 95% CIs were estimated for the three exposure variables separately using multilevel multinomial logistic regression models with zBMI categories as the outcome, adjusting in model 1 for age, sex, ethnicity and number of family members and in model 2 adding family income. A joint measure was derived combining income and deprivation measures.

RESULTS

A total of 5962 children were included. Low family income (Q1 vs Q5: OR=4.69, 95% CI 2.65 to 8.29), low neighbourhood income (Q1 vs Q5: OR=2.18, 95% CI 1.33 to 3.58) and high neighbourhood deprivation (Q1 vs Q5: OR=2.45, 95% CI 1.52 to 3.95) were each associated with increased OR of child obesity. However, after adjustment for family income, the association for both neighbourhood income (OR=1.39, 95% CI 0.82 to 2.34) and deprivation (OR=1.56, 95% CI 0.94 to 2.58) and obesity was attenuated. Children from low-income families living in low-income or high deprivation neighbourhoods had higher OR of obesity.

CONCLUSION

Child obesity was independently associated with low family-level income and a joint measure suggests that neighbourhood also matters. Socioeconomic inequalities at both individual and neighbourhood levels should be addressed in childhood obesity interventions.

Public health preventive measures and child health behaviours during COVID-19: a cohort study

Objective

The primary objective was to determine the association between public health preventive measures and children’s outdoor time, sleep duration, and screen time during COVID-19.

Methods

A cohort study using repeated measures of exposures and outcomes was conducted in healthy children (0 to 10 years) through The Applied Research Group for Kids (TARGet Kids!) COVID-19 Study of Children and Families in Toronto, Canada, between April 14 and July 15, 2020. Parents were asked to complete questionnaires about adherence to public health measures and children’s health behaviours. The primary exposure was the average number of days that children practiced public health preventive measures per week. The three outcomes were children’s outdoor time, total screen time, and sleep duration during COVID-19. Linear mixed-effects models were fitted using repeated measures of primary exposure and outcomes.

Results

This study included 554 observations from 265 children. The mean age of participants was 5.5 years, 47.5% were female and 71.6% had mothers of European ethnicity. Public health preventive measures were associated with shorter outdoor time (−17.2; 95% CI −22.07, −12.40; p < 0.001) and longer total screen time (11.3; 95% CI 3.88, 18.79; p = 0.003) during COVID-19. The association with outdoor time was stronger in younger children (<5 years), and the associations with total screen time were stronger in females and in older children (≥5 years).

Conclusion

Public health preventive measures during COVID-19 were associated with a negative impact on the health behaviours of Canadian children living in a large metropolitan area.

Supplementary Information

The online version contains supplementary material available at 10.17269/s41997-021-00549-w.

Automated Self-Administered 24-H Dietary Assessment Tool (ASA24) recalls for parent proxy-reporting of children's intake (> 4 years of age): a feasibility study

BACKGROUND

Robust measurement of dietary intake in population studies of children is critical to better understand the diet-health nexus. It is unknown whether parent proxy-report of children's dietary intake through online 24-h recalls is feasible in large cohort studies.

OBJECTIVES

The primary objective of this study was to describe the feasibility of the Automated Self-Administered 24-h Dietary Assessment Tool (ASA24) to measure parent proxy-reported child dietary intake. A secondary objective was to compare intake estimates with those from national surveillance.

METHODS

Parents of children aged 4-15 years participating in the TARGet Kids! research network in Toronto, Canada were invited by email to complete an online ASA24-Canada-2016 recall for their child, with a subsample prompted to complete a second recall about 2 weeks later. Descriptive statistics were reported for ASA24 completion characteristics and intake of several nutrients. Comparisons were made to the 2015 Canadian Community Health Survey (CCHS) 24-h recall data.

RESULTS

A total of 163 parents completed the first recall, and 46 completed the second, reflecting response rates of 35% and 59%, respectively. Seven (4%) first recalls and one (2%) second recall were excluded for ineligibility, missing data, or inadvertent parental self-report. The median number of foods reported on the first recall was 18.0 (interquartile range (IQR) 6.0) and median time to complete was 29.5 min (IQR 17.0). Nutrient intakes for energy, total fat, protein, carbohydrates, fiber, sodium, total sugars, and added sugars were similar across the two recalls and the CCHS.

CONCLUSIONS

The ASA24 was found to be feasible for parent proxy-reporting of children's intake and to yield intake estimates comparable to those from national surveillance, but strategies are needed to increase response rate and support completion to enhance generalizability.

The social determinants of health as predictors of adherence to public health preventive measures among parents and young children during the COVID-19 pandemic: a longitudinal cohort study

Objectives

To investigate whether social determinants of health (SDOH) are predictive of adherence to public health preventive measures and to describe changes in adherence over time among parents and children.

Methods

A longitudinal study was conducted in children aged 0–10 years and their parents through the TARGet Kids! COVID-19 Study in the Greater Toronto Area, Canada (April–July 2020). This study included 335 parents (2108 observations) and 416 children (2632 observations). Parents completed weekly questionnaires on health, family functioning, socio-demographics, and public health practices. The outcome was adherence to public health preventive measures measured separately for parents and children. Marginal log-binomial models were fitted using repeated measures of the outcome and predictors.

Results

Unemployment (RR 0.67, 95% CI: 0.47, 0.97), apartment living (RR 0.72, 95% CI: 0.53, 0.99), and essential worker in the household (RR 0.74, 95% CI: 0.55, 1.00) were associated with decreased likelihood of adherence among parents; however, no associations were observed for other SDOH, including family income and ethnicity. Furthermore, there was no strong evidence that SDOH were associated with child adherence. The mean number of days/week that parents and children adhered at the start of the study was 6.45 (SD = 0.93) and 6.59 (SD = 0.86), respectively, and this decreased to 5.80 (SD = 1.12) and 5.84 (SD = 1.23) by study end. Children consistently had greater adherence than parents.

Conclusion

SDOH were predictive of adherence to public health preventive measures among parents but less so in children among our sample of relatively affluent urban families. Adherence was high among parents and children but decreased over time. Equitable approaches to support the implementation of public health guidelines may improve adherence.

Supplementary Information

The online version contains supplementary material available at 10.17269/s41997-021-00540-5.

Body Mass Index Mediates the Association between Growth Trajectories and Cardiometabolic Risk in Children

Background: Few studies have published mediation analyses to quantify the role concurrent BMI plays in the relationship between growth and cardiometabolic risk (CMR) outcomes. Methods: We used data from a longitudinal cohort study conducted in children aged 0-60 months through The Applied Research Group for Kids (TARGet Kids!) in Canada. Four age and sex standardized BMI (zBMI) trajectories were identified using latent class mixed models. CMR were assessed using a CMR score. Concurrent zBMI was the zBMI measured on the same visit as CMR. Mediation analyses were performed comparing each trajectory with the reference trajectory. Results: One thousand one hundred sixty-five children were included. On average, compared with being in the stable low trajectory, being in the catch-up trajectory was associated with an increased CMR score of 0.42, 0.28 of which was mediated through concurrent zBMI [95% confidence interval (CI) 0.17 to 0.41, p = 0.001]; being in the stable high trajectory was associated with an increased CMR score of 0.23, 0.24 through concurrent zBMI (95% CI 0.18 to 0.31, p < 0.001). Similarly, being in the rapid accelerating trajectory was associated with an increased CMR score of 1.43, 1.18 of which was through concurrent zBMI (95% CI 0.89 to 1.50, p < 0.001). Conclusions: There was a strong evidence that the effect of BMI trajectories on CMR was indirect via concurrent BMI. It is important for researchers to choose the most appropriate analytic method based on the study hypothesis to understand the total or direct effect of growth patterns on cardiometabolic disease risk in children.

117 Using composite area-level measures as a proxy for self-report family income

Background

Socioeconomic status (SES) is a well-established social determinant of child health. When reliable self-report family income is unavailable, area-level measures, such as median neighbourhood income, are commonly used as a proxy. However, median neighbourhood income is not a good proxy for self-report family income. Newer area-level measures, such as the Neighbourhood Equity Score (NES) and the Child and Family Inequities Score (CFIS) are composite scores comprised of indicators of well-being such as income, parental education and physical surroundings.

Objectives

The primary objective was to evaluate the agreement between self-report family income and three area-level measures: median neighbourhood income, NES, and CFIS. The secondary objective was to examine the association between self-report family income, NES, and CFIS with two health indicators associated with SES: overweight/obesity (BMI z-score&gt;1) and short breastfeeding duration (&lt;6 months).

Design/Methods

We conducted a cross-sectional study using data from a healthy urban Canadian cohort of young children (0-5 years) attending a scheduled health supervision visit in primary care. Parents completed a questionnaire including family income, postal code and breastfeeding duration. Research assistants measured height and weight (to calculate body mass index). Postal code was used to determine each area-level measure. Agreement between self-report family income and area-level measures was evaluated using kappa coefficients. The percentage of families accurately classified by area-level measures compared with self-report family income was calculated. Multivariable logistic regression was used to evaluate the association between self-report family income, NES, and CFIS (quintiles) with the two health indicators (present/absent).

Results

5149 children were included (mean age 21 months). Agreement between self-report family income and both NES and CFIS was ‘fair’ (weighted k=0.29 for both), and agreement with median neighbourhood income was ‘poor’ (weighted k=0.09). Accurate classification between self-report family income and the three measures were: median neighbourhood income (5.6%), NES (32.2%), CFIS (32.4%). For children in the lowest vs. highest quintile, the odds (95% CI) of overweight/obesity were: self-report family income OR=2.75 (1.60-4.72), NES OR=2.02 (1.23-3.30), CFIS OR=2.04 (1.25-3.33); and having short breastfeeding duration: self-report family income OR=1.61 (1.32-1.97), NES OR=1.84 (1.50-2.25), CFIS OR=1.84 (1.46-2.31).

Conclusion

Agreement and accurate classification between self-report family income was strongest for composite area-level measures (NES and CFIS), compared with median neighbourhood income. Both self-report family income and composite area-level measures supported the same conclusion that lower SES was associated with poorer health outcomes. These newer measures may be more appropriate than median neighbourhood income when self-report family income is unavailable.

The association between body mass index trajectories and cardiometabolic risk in young children

BACKGROUND

Rapid growth is associated with increased cardiometabolic risk (CMR) in adolescence and adulthood. Little is known about whether the association between rapid growth and increased CMR originates in early childhood.

OBJECTIVES

To identify age and sex standardized body mass index (zBMI) trajectories and to examine the association between zBMI trajectories and CMR outcomes in children 0 to 60 months.

STUDY DESIGN

A longitudinal cohort study was conducted through The Applied Research Group for Kids (TARGet Kids!) in Toronto, Canada. Participants had repeated measures of weight and length or height performed from birth to 60 months of age. Latent class mixed modelling was used to identify the zBMI trajectories. Linear regressions were performed to determine the association between zBMI trajectories and the primary outcome, a CMR score, quantified as the sum of age- and sex- standardized waist circumference, systolic blood pressure, glucose, log-triglycerides and negative high-density lipoprotein cholesterol (HDL-C), divided by √5. Secondary outcomes were the individual components of the CMR formula as well as diastolic blood pressure and non-HDL-C.

RESULTS

Four BMI trajectories were identified among the 1166 children. After adjusting for all covariates, children in the rapidly accelerating trajectory had increased total CMR score (β = 1.38, 95% CI 0.77; 1.99, P < .001) and increased waist circumference score (β = 2.39, 95% CI 1.92; 2.86, P < .001) compared to the stable low group.

CONCLUSIONS

Rapid growth during early childhood is associated with increased CMR in preschool children, largely driven by larger waist circumference.

Outlier Detection in Growth Data: Beyond Biologically Implausible Values

Objectives

Eliminating anthropometry measurement error and employing outlier and biological implausible values (BIV) detection methods adapted to longitudinal measurements is important for the study of growth. This work aimed to review and assess the accuracy of the available BIV and outlier detection methods and propose a growth trajectory outlier detection method.

Methods

We included 2354 infants from the Applied Research Group for Kids (TARGet Kids! ) cohort-based in Toronto (ON, Canada) that recruits healthy children from birth to 5 years of age. We considered infants with at least 8 length and weight measurements available between the 1st and the 24th month of age. Weight-for-length z-scores (wflz) were calculated using the WHO growth standards. Outlier measurements were randomly introduced in 5% of the wflz measurements using a normal distribution (μ = 0, σ = 1). We employed 4 outlier detection methods; an empirical detection method for BIV using the cut-offs derived from the WHO Child Growth Standards, a clustering method, a method based on cluster prototypes for individual outlier measurements and a method based on cluster prototypes for entire growth trajectories. Each method was applied individually and evaluated using the sensitivity and specificity indexes based on the manually introduced outliers. We also calculated the Kappa statistic to evaluate the agreement of each method against the manual outliers.

Results

After excluding premature (&lt;37 weeks), low birth weight (&lt;1500 g) neonates and children with missing length and weight measurements, we analyzed 393 children with a total of 3144 measurements. Sensitivity and specificity for the four methods ranged between 4.4%–55.0% and 83.7% −99.7%, respectively, with kappa being non-significant (P &gt; 0.05) only for the empirical. The clustering detection method reported a higher finding rate, while the empirical method found most of the BIV, but few of the rest of the outliers.

Conclusions

BIV account for a small portion of the possible outliers in growth datasets. We show that additional statistical or model-based methods are required for a more comprehensive outlier detection process, which has implications for growth analysis and nutritional assessment.

Funding Sources

Joannah and Brian Lawson Center for Child Nutrition, Connaught Fund, Onassis Foundation.

The association between screen time and cardiometabolic risk in young children

OBJECTIVES

While studies exist on the association between screen time and cardiometabolic risk among adolescents, research examining the effect of screen time on cardiometabolic risk in young children is lacking. The primary objective of this study was to examine the association between daily screen time and cardiometabolic risk (CMR) [sum of age- and sex-standardized z-scores of systolic blood pressure (SBP), glucose, log-triglycerides, waist circumference (WC), and negative high-density lipoprotein (HDL) cholesterol divided by the square root of five] in young children. Secondary objectives included examining individual CMR risk factors, including waist-to-height ratio and non high-density lipoprotein (non-HDL) cholesterol, as well as the individual cut-offs of these risk factors. Additional analyses include examining the association between screen time and CMR by handheld/non-handheld devices.

METHODS

A study was conducted among young children 3 to 6 years from the TARGet Kids! practice-based research network in Toronto and Montreal, Canada. Children with one or more measures of screen time and CMR were included in this study. Generalized estimating equation (GEE) multivariable linear regressions and multivariable logistic regressions, using published cut-offs, were conducted to evaluate these associations.

RESULTS

Data from 1317 children [mean age 52 months (SD = 13.36), 44.34% female] were included for analyses. There was no evidence of associations between screen time and total CMR score or individual risk factors (p > 0.05) after adjusting for confounders. A statistically significant, but small association between daily screen time and non-HDL cholesterol was found (B = 0.046; CI = [0.017 to 0.075]; p = 0.002.

CONCLUSIONS

Though no relationship was reported between daily screen time and the majority of CMR factors in early childhood, there was an association between daily screen time and non-HDL cholesterol. As the relationship between daily screen time and CMR factors may not be apparent in early childhood, studies to evaluate longer-term cardiometabolic effects of screen time are needed. Although there is an evidence-based rationale to reduce screen time in early childhood, prevention of cardiometabolic risk may not be the primary driver.