Social patterning of childhood overweight in the French national ELFE cohort.

An inverse social gradient in early childhood overweight has been consistently described in high-income countries; however, less is known about the role of migration status. We studied the social patterning of overweight in preschool children according to the mother's socio-economic and migration background. For 9250 children of the French ELFE birth cohort with body mass index collected at age 3.5 years, we used nested logistic regression to investigate the association of overweight status in children with maternal educational level, occupation, household income and migration status. Overall, 8.3% (95%CI [7.7-9.0]) of children were classified as overweight. The odds of overweight was increased for children from immigrant mothers (OR 2.22 [95% CI 1.75-2.78]) and descendants of immigrant mothers (OR 1.35 [1.04-2.78]) versus non-immigrant mothers. The highest odds of overweight was also observed in children whose mothers had low education, were unemployed or students, or were from households in the lowest income quintile. Our findings confirm that socio-economic disadvantage and migration status are risk factors for childhood overweight. However, the social patterning of overweight did not apply uniformly to all variables. These new and comprehensive insights should inform future public health interventions aimed at tackling social inequalities in childhood overweight.

Impact of parental lifestyle patterns in the preconception and pregnancy periods on childhood obesity.

Introduction: High prevalence of overweight and obesity already observed in preschool children suggests the involvement of early-life risk factors. Preconception period and pregnancy are crucial windows for the implementation of child obesity prevention interventions with parental lifestyle factors as relevant targets. So far, most studies have evaluated their role separately, with only a few having investigated their potential synergistic effect on childhood obesity. Our objective was to investigate parental lifestyle patterns in the preconception and pregnancy periods and their association with the risk of child overweight after 5 years. Materials and methods: We harmonized and interpreted results from four European mother-offspring cohorts participating in the EndObesity Consortium [EDEN, France; Elfe, France; Lifeways, Ireland; and Generation R, Netherlands] with data available for 1,900, 18,000, 1,100, and 9,500 families, respectively. Lifestyle factors were collected using questionnaires and included parental smoking, body mass index (BMI), gestational weight gain, diet, physical activity, and sedentary behavior. We applied principal component analyses to identify parental lifestyle patterns in preconception and pregnancy. Their association with risk of overweight (including obesity; OW-OB) and BMI z-scores between 5 and 12 years were assessed using cohort-specific multivariable logistic and linear and regression models (adjusted for potential confounders including parental age, education level, employment status, geographic origin, parity, and household income). Results: Among the various lifestyle patterns derived in all cohorts, the two explaining the most variance were characterized by (1) "high parental smoking, low maternal diet quality (and high maternal sedentary behavior in some cohorts)" and, (2) "high parental BMI and low gestational weight gain." Patterns characterized by high parental BMI, smoking, low diet quality or high sedentary lifestyle before or during pregnancy were associated with higher risk of OW-OB in children, and BMI z-score at any age, with consistent strengths of associations in the main cohorts, except for lifeways. Conclusion: This project provides insight into how combined parental lifestyle factors in the preconception and pregnancy periods are associated with the future risk of child obesity. These findings are valuable to inform family-based and multi-behavioural child obesity prevention strategies in early life.

Child health screening program in French nursery schools: Results and related socioeconomic factors.

Objectives: The study aims to describe the output of routine health screening performed in French nursery schools by the maternal and child health services among children aged 3-4 years and to quantify the level of early socioeconomic health disparities. Methods: In 30 participating départements, data on screening for vision and hearing impairments, overweight and thinness, dental health, language, psychomotor development, and immunizations were collected for children born on specific dates in 2011 and enrolled in nursery school in 2014-2016. Information was collected on the children, their socioeconomic characteristics and on the school attended. Odds of abnormal screening results were compared for each socioeconomic factor by logistic regressions adjusted for age, sex, prematurity and bilingualism. Results: Among the 9,939 children screened, prevalence of disorders was 12.3% for vision, 10.9% for hearing, 10.4% for overweight, 7.3% for untreated caries, 14.2% for language and 6.6% for psychomotricity. Newly detected visual disorders were more frequent in disadvantaged areas. Children with unemployed parents were three time more likely to have untreated caries and twice as likely to present language or psychomotor impairments; 52% were referred to a health professional following screening compared to 39% of children with employed parents. Except for children in disadvantaged areas, vaccine coverage was lower among disadvantaged groups. Conclusion: The prevalences of impairments, which are higher among disadvantaged children, highlight the potential preventive impact of systematic screening under the comprehensive maternal and child healthcare program. These results are important to quantify early socioeconomic inequalities in a Western country known for its generous social welfare system. A more holistic approach to child health is needed with a coherent system involving families and aligning primary care, local child health professionals, general practitioners, and specialists. Further results are needed to evaluate its impact on later child development and health.

Parental lifestyle patterns around pregnancy and risk of childhood obesity in four European birth cohort studies.

BACKGROUND: A high prevalence of excess weight in children younger than 5 years suggests the involvement of early-life risk factors. The preconception and pregnancy periods are crucial stages for the implementation of interventions to prevent childhood obesity. Most studies so far have evaluated the effects of early-life factors separately, with only a few investigating the combined effect of parental lifestyle factors. Our objective was to fill the literature gap regarding parental lifestyle factors in the preconception and pregnancy periods and to study their association with the risk of overweight in children after the age of 5 years. METHODS: We harmonised and interpreted data from four European mother-offspring cohorts (EDEN [comprising 1900 families], Elfe [comprising 18 000 families], Lifeways [comprising 1100 families], and Generation R [comprising 9500 families]). Written informed consent was obtained from parents of all involved children. Lifestyle factor data collected through questionnaires comprised parental smoking, BMI, gestational weight gain, diet, physical activity, and sedentary behaviour. We applied principal component analyses to identify multiple lifestyle patterns in preconception and pregnancy. Their association with child BMI z-score and risk of overweight (including obesity, overweight and obesity, as defined by the International Task Force reference) between the ages of 5 and 12 years were assessed using cohort-specific multivariable linear and logistic regression models (adjusted for confounders including parental age, education level, employment status, geographic origin, parity, and household income). FINDINGS: Among the various lifestyle patterns identified in all cohorts, the two that better explained variance were high parental smoking plus low maternal diet quality or high maternal sedentary behaviour, and high parental BMI plus low gestational weight gain. Overall, we observed that patterns characterised by high parental BMI, smoking, low-quality diet, or sedentary lifestyle before or during pregnancy were associated with higher BMI z-scores and risk of overweight and obesity in children aged 5-12 years. INTERPRETATION: Our data contribute to a better understanding of how parental lifestyle factors might be associated with the risk of childhood obesity. These findings are valuable to inform future family-based and multi-behavioural child obesity prevention strategies in early life. FUNDING: European Union's Horizon 2020 under the ERA-NET Cofund action (reference 727565) and European Joint Programming Initiative "A Healthy Diet for a Healthy Life" (JPI HDHL, EndObesity).

Sociodemographic and behavioural factors of adherence to the no-screen guideline for toddlers among parents from the French nationwide Elfe birth cohort.

BACKGROUND: Excessive screen time in infancy and childhood has been associated with consequences on children's development and health. International guidelines call for no screen time before age 2 years, whereas in France, the most prominent guidelines recommend no screen before age 3 years. However, data are lacking on parental adherence to the no-screen guideline for toddlers and factors of adherence in France. Using data from the French nationwide Elfe birth cohort, we estimated adherence to the no-screen guideline at age 2 years and examined related factors, including sociodemographic characteristics, parental leisure activities and screen time. METHODS: In 2011, 18,329 newborns and their parents were enrolled in 349 randomly selected maternity units across mainland France. At age 2 years, screen exposure of 13,117 toddlers was reported by parents in phone interviews. Data on sociodemographic characteristics, parental leisure activities and screen time were collected from both parents. Three patterns of parental leisure activities were derived by principal component analysis: literate (e.g.,reading), screen-based, and physical/artistic activities. Multivariable logistic regression models were used to examine the associations of sociodemographic characteristics, parental leisure activities and parental screen time with adherence to the no-screen guideline for toddlers. RESULTS: Overall, 1809/13,117 (13.5%) families adhered to the no-screen guideline for toddlers. Adherence was reduced with maternal age < 40 years, low parental education, single-parent household and parental migration status. After adjusting for sociodemographic characteristics, adherence to the guideline was positively associated with a parental literate activity pattern (mothers: odds ratio [95% confidence interval]: 1.15 [1.08, 1.22]); fathers: 1.15 [1.07, 1.23]) and negatively with a screen-based activity pattern (mothers: 0.73 [0.69, 0.77]; fathers: 0.81 [0.76, 0.87]). With each additional hour of parental screen time, mothers and fathers were less likely to adhere to the guideline (mothers: adjusted odds ratio 0.80 [0.77, 0.83]; fathers: 0.88 [0.85, 0.91]). CONCLUSIONS: Adherence to the no-screen guideline for toddlers in France was low. Parental leisure activities and parental screen time are major factors of adherence to the no-screen guideline and could be considered in targeted public health interventions.

TV, computer, tablet and smartphone use and autism spectrum disorder risk in early childhood: a nationally-representative study.

BACKGROUND: Screen media use in early childhood has largely increased in recent years, even more so during the COVID-19 epidemic, and there is much discussion regarding its influence on neurodevelopment, including Autism Spectrum Disorder (ASD). METHODS: We examined the relationship between use of TV, computer, tablet and smartphone at age 2 years and risk of ASD assessed in telephone-based questionnaires among 12,950 children participating in the nationally representative ELFE ('Etude Longitudinale Française sur les Enfants') birth cohort study in France. RESULTS: In inverse-probability weighted (IPW) multinomial regression analyses, children's weekly or daily screen media use was associated with an increased likelihood of an intermediate risk of ASD (IPW-controlled OR for weekly use:1.07, 95% CI 1.02-1.12; IPW-controlled OR for daily use:1.05, 95% CI 1.02-1.08) but inversely associated with a high risk (IPW-controlled OR for weekly use: 0.60, 95% CI 0.50-0.73; IPW-controlled OR for daily use: 0.75, 95% CI 0.62-0.91), as ascertained by the M-CHAT. This was confirmed when studying TV as well as computer/tablet exposure separately. CONCLUSIONS: Overall, our nationally-representative study conducted among a large sample of 2-year-old children, indicates a complex relationship between screen exposure and ASD risk.

Comparison of methods for estimating the attributable risk in the context of survival analysis.

BACKGROUND: The attributable risk (AR) measures the proportion of disease cases that can be attributed to an exposure in the population. Several definitions and estimation methods have been proposed for survival data. METHODS: Using simulations, we compared four methods for estimating AR defined in terms of survival functions: two nonparametric methods based on Kaplan-Meier's estimator, one semiparametric based on Cox's model, and one parametric based on the piecewise constant hazards model, as well as one simpler method based on estimated exposure prevalence at baseline and Cox's model hazard ratio. We considered a fixed binary exposure with varying exposure probabilities and strengths of association, and generated event times from a proportional hazards model with constant or monotonic (decreasing or increasing) Weibull baseline hazard, as well as from a nonproportional hazards model. We simulated 1,000 independent samples of size 1,000 or 10,000. The methods were compared in terms of mean bias, mean estimated standard error, empirical standard deviation and 95% confidence interval coverage probability at four equally spaced time points. RESULTS: Under proportional hazards, all five methods yielded unbiased results regardless of sample size. Nonparametric methods displayed greater variability than other approaches. All methods showed satisfactory coverage except for nonparametric methods at the end of follow-up for a sample size of 1,000 especially. With nonproportional hazards, nonparametric methods yielded similar results to those under proportional hazards, whereas semiparametric and parametric approaches that both relied on the proportional hazards assumption performed poorly. These methods were applied to estimate the AR of breast cancer due to menopausal hormone therapy in 38,359 women of the E3N cohort. CONCLUSION: In practice, our study suggests to use the semiparametric or parametric approaches to estimate AR as a function of time in cohort studies if the proportional hazards assumption appears appropriate.