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Contexte : Il subsiste encore des questionnements sur l’impact de la fréquentation d’un service de garde (SDG) sur le développement des enfants à court et long-terme. Tout d’abord, peu d’études analysent l’individu comme un « tout » multidimensionnel qui évolue dans le temps. Ensuite, très peu d’études ont considéré l’impact des SDG sur les enfants provenant de famille avec un haut statut socioéconomique (SSE). Finalement, nous connaissons encore très peu des mécanismes qui expliquent les associations à long terme entre les SDG et le développement de l’enfant. Objectif: L’objectif principal de cette thèse est ainsi d’étudier les associations entre l’exposition a certaines caractéristiques de SDG en petite enfance et le développement des enfants à court et à long terme avec une approche de parcours de vie centré sur la personne. Dans le premier article, nous étudions l’association entre les patrons de fréquentation de SDG et le profil de développement cognitif. Dans le deuxième article, nous étudions l’association entre l’utilisation d’un SDG et le taux de graduation du secondaire. Finalement, dans le troisième article, nous tentons de déterminer quel mécanisme explique l’association entre les SDG et le développement à long terme. Méthode : Les trois articles analysent les enfants provenant de l’Étude Longitudinale du Développement des Enfants du Québec (ELDEQ). Dans l’article 1, nous avons effectué une régression logistique multinomiale afin de quantifier l’association entre l’intensité et le type de SDG, et des trajectoires de développement cognitif en étudiant l’interaction avec le SSE et le sexe. Dans l’article 2 et 3, des données administratives ont été utilisées afin de déterminer si les enfants avaient obtenu un diplôme d’étude secondaire à 20 ans. Dans l’article 2, nous avons effectué une analyse de régression logistique afin de déterminer si l’intensité et le type de SDG étaient associés à la graduation. Dans l’article 3, la performance académique, les compétences sociales, et la santé sont examinées comme médiateur potentiel de l’association observé dans l’article 2. Résultats : Dans l’article 1, les enfants provenant de familles ayant un haut SSE qui fréquentaient un SDG en centre à partir d’environ 3 ans et demi avaient moins de chances de se retrouver dans la trajectoire de développement cognitif fort comparativement aux enfants étant dans un autre type de SDG. Dans les articles 2 et 3, les enfants ayant fréquenté un SDG en centre tôt (avant d’être bambin) avaient plus de chances de graduer du secondaire et la santé à 6 ans expliquait partiellement cette association. Implications: Cette thèse souligne l’importance de comprendre comment les caractéristiques des SDG et des enfants interagissent pour influencer différentes mesures du développement. Nos résultats suggèrent également que la santé pourrait être un mécanisme clé expliquant un plus haut taux de graduation pour les enfants fréquentant un SDG en centre tôt. Les études futures devraient élargir leur horizon afin d’inclure des variables comme la santé et afin de mieux comprendre comment les SDG affectent les enfants provenant de familles ayant un haut SSE. / Context : After years of research on the effects of child care services (CCS) on development, there remains questions regarding how CCS can affect development in the short and long term. Few studies have regarded the child as a whole, multidimensional being that evolves through time. Additionally, few studies have considered the impact of CCS on children from high socioeconomic status (SES) families. Finally, we still know very little about the underlying mechanisms that would explain how CCS can influence long-term development. Objective: The main objective of this thesis is therefore to study the association between certain characteristics of CCS use and child development in the short and long term using a life course, person-centered approach. The first article investigates the association between patterns of CCS use and profiles of cognitive development. The second article examines the association between patterns of CCS use and high school graduation. The third article investigates the underlying mechanisms that could explain the association between CCS and long-term development. Method: The three articles studied children from the Quebec Longitudinal Study of Child Development (QLSCD). In the first article, we performed a multinomial logistic regression to investigate the association between intensity and type of CCS through early childhood and trajectories of cognitive development while considering interactions with SES and sex. In articles 2 and 3, administrative records were used to determine whether students had obtained a high school diploma by age 20 years. In article 2, we used a logistic regression to determine if intensity and type of CCS throughout early childhood were associated with high school graduation. In article 3, academic performance, social skills, and health were examined as potential mediators of the association measured in article 2. Results: In article 1, children from high SES families who attended center-based CCS after 3 and half years were less likely to be in the high cognitive development trajectory, compared to children in all other types of care. In article 1 and 2, children who attended center-based CCS early (before toddlerhood) were more likely to graduate from high school and better health partly explained this association. Implications: This thesis underlines the importance of understanding how the characteristics of the CCS experience and of the child interact together to influence different measures of development. Our results also suggest that improved health following early center-based CCS attendance could be a key mechanism explaining positive long-term outcomes such as high school graduation. Future studies on the effects of CCS on development should broaden their scope to include new variables such as health and to better understand how CCS can affect children from high SES families.

In der Dissertation wurden Effekte der zuwanderungsbezogenen Klassenzusammensetzung auf verschiedene Leistungsmaße und psychosoziale Schülermerkmale im Rahmen von drei Zeitschriftenbeiträgen untersucht. In Teilstudie eins wurden Effekte der sozialen und zuwanderungsbezogenen Zusammensetzung auf das Leseverständnis im Verlauf der neunten Klasse und deren Vermittlung durch Merkmale der Unterrichtsqualität analysiert. Der Klassenanteil von Heranwachsenden mit Zuwanderungshintergrund war unter Kontrolle des mittleren sozioökonomischen Status nicht mit der Leseleistung assoziiert. Es zeigten sich Hinweise einer partiellen Vermittlung des Effekts sozialer Zusammensetzung durch das Ausmaß herausfordernden Sprachunterrichts. Teilstudie zwei beschäftigte sich mit Effekten der Zusammensetzung auf die Lernmotivation im Verlauf der neunten Klasse und deren Vermittlung durch das Ausmaß schülerorientierten Unterrichtsklimas. Heranwachsende mit Zuwanderungshintergrund berichteten höhere Motivation, wenn sie Klassen mit einem höheren Anteil von Heranwachsenden mit Zuwanderungshintergrund besuchten. Es zeigten sich keine vermittelten Effekte durch Merkmale des Unterrichtsklimas. In Teilstudie drei wurden der Anteil von Kindern mit Zuwanderungshintergrund und Maße zuwanderungsbezogener Heterogenität in ihrer Assoziation mit Mathematik- und Leseleistung sowie dem Verbundenheitsgefühl mit Peers von Kindern der vierten Klasse verglichen. Es bestanden stärkere negative Effekte des Klassenanteils im Vergleich zu Heterogenitätsmaßen. Bei simultaner Berücksichtigung von Klassenanteil und Heterogenitätsmaßen waren Heterogenitätseffekte größtenteils nicht mehr signifikant. Es zeigten sich jedoch leicht positive Heterogenitätseffekte auf die Mathematikleistung. Es bestanden keine Effektunterschiede zwischen Heterogenitätsmaßen. Die Befunde verweisen auf die Bedeutung der Schulklasse für die akademische Entwicklung sowie für die Erklärung zuwanderungsbezogener Disparitäten im Bildungssystem. / The thesis at hand explored effects of the language-related and ethnic makeup of classrooms on several achievement outcomes as well as psychosocial outcomes in three research articles. The first article investigated effects of socioeconomic and language minority classroom composition on ninth graders’ reading achievement across two measurement points and explored the mediating role of instructional quality. The proportion of minority students had no effect on achievement after controlling for the socioeconomic composition. The results suggest that the effect of the socioeconomic composition on achievement may be mediated partially by the teacher’s focus on language during instruction. The second article focused on effects of the proportion of language minority students on the development of ninth graders’ motivation and the mediating role of a student-oriented climate. The analyses revealed that minority students were increasingly motivated in classrooms with a higher proportion of minority students. The compositional effect was not mediated by the instructional climate. The third article explored various measures of the ethnic makeup of classrooms and their relationship with student outcomes. The proportion of minority students and measures of diversity were compared in their prediction of fourth graders’ achievement in math and reading as well as the feeling of belonging with one’s peers. The proportion of minority students showed stronger negative effects on student outcomes than the diversity measures. Including diversity measures and the proportion of minority students, the diversity effects mostly lost their significance. However, students showed slightly higher levels of math achievement in more diverse classrooms. The various measures of diversity led to similar results. The findings add to the evidence indicating that the classroom learning environment affects students’ academic development and contributes to ethnic disparities in the education system.

This dissertation was carried out to try to describe the role of socio-economic factors in the successful completion of schooling up to matriculation level (matric), among young mothers in the Soutpansberg East Circuit in Limpopo Province, South Africa. The researcher used the social capital theoretical framework. A questionnaire was administered to 128 young mothers, aged 18 and above, after a pilot survey had been carried out. The data was captured, exported and analysed The data was then exported to the latest model of the Statistical Package for the Social Sciences (SPSS) version 25 where it was analysed. The research used independent T-test analysis, analysis of variance (ANOVA) and correlation analysis. The independent T- test was used to determine if the views of young mothers differed by the number of children, form of support from father, school policy and presence of educators as counsellors. A one-way analysis of variance (ANOVA) was done to determine whether the views on the role of socioeconomic factors in the successful completion of matric among young mothers in the Soutpansberg East Circuit, Limpopo Province, South Africa differed by age, grade, type of family and who takes care of the child. The findings showed that there were several socioeconomic factors that assisted young mothers to complete matric, among them were, family supports, child support grants, intra-school environment and policies. They provided critical support to the young mother in different forms among others taking care of children while they were at school, financial support, encouragement. The study also found other that schools in the Soutpansberg East Circuit also provided a significant amount of support to young mothers. The study also found a general trend of absentee fatherhood in the caring of children. The study found out that there was a complicated interplay of different socioeconomic factors to the completion of matric among the young mothers. The researcher, therefore, concluded that socio-economic factors are critical for the successful completion of schooling up to matric level in the Soutpansberg East Circuit. The study found out the need for more empirical study in the role of socioeconomic factors to the complication of matric among young mothers. / Sociology / M.A. (Sociology)

Newborn screening programs measure analyte levels in neonatal blood spots to identify individuals at high risk of disease. Carnitine and acylcarnitine levels are primary markers used in the detection of fatty acid oxidation disorders. These analytes may be influenced by certain pre/perinatal or newborn screening related factors. The primary objective of this study was to explore the association between these characteristics and levels of blood carnitines and acylcarnitines in the newborn population. The study was composed of two parts: a systematic review and a clinical database analysis of existing newborn screening data. The systematic review results suggested considerable variability across studies in the presence and directionality of associations between analyte levels and birth weight, gestational age, age at time of blood spot collection, type of sample, and storage time. Sex was not significantly associated with carnitine or acylcarnitine levels in neonatal blood. We identified a need to more fully investigate a potential interaction between gestational age and birth weight in regard to analyte levels. The secondary data analyses indicated a statistically significant relationship between analyte levels and all perinatal / infant and newborn screening related factors of interest, but effect sizes were generally small. The interaction between gestational age and birth weight was significant in all models; when further explored through graphical analysis with conditional means, extremely premature neonates stood out as having distinct analyte patterns in relation to birth weight. Variation in the ratio of total acylcarnitine to free carnitine was better accounted for by the perinatal and newborn factors than was variation in any individual carnitine or acylcarnitine, indicating that proportions of carnitine and acylcarnitines may be more important in understanding an individual’s metabolic functioning than individual analyte levels. A low proportion of variation was explained in all multivariate models, supporting the use of universal algorithms in newborn screening and suggesting the need for further large scale empirical research targeted at previously unaccounted for perinatal factors such as birth stress.

Newborn screening programs measure analyte levels in neonatal blood spots to identify individuals at high risk of disease. Carnitine and acylcarnitine levels are primary markers used in the detection of fatty acid oxidation disorders. These analytes may be influenced by certain pre/perinatal or newborn screening related factors. The primary objective of this study was to explore the association between these characteristics and levels of blood carnitines and acylcarnitines in the newborn population. The study was composed of two parts: a systematic review and a clinical database analysis of existing newborn screening data. The systematic review results suggested considerable variability across studies in the presence and directionality of associations between analyte levels and birth weight, gestational age, age at time of blood spot collection, type of sample, and storage time. Sex was not significantly associated with carnitine or acylcarnitine levels in neonatal blood. We identified a need to more fully investigate a potential interaction between gestational age and birth weight in regard to analyte levels. The secondary data analyses indicated a statistically significant relationship between analyte levels and all perinatal / infant and newborn screening related factors of interest, but effect sizes were generally small. The interaction between gestational age and birth weight was significant in all models; when further explored through graphical analysis with conditional means, extremely premature neonates stood out as having distinct analyte patterns in relation to birth weight. Variation in the ratio of total acylcarnitine to free carnitine was better accounted for by the perinatal and newborn factors than was variation in any individual carnitine or acylcarnitine, indicating that proportions of carnitine and acylcarnitines may be more important in understanding an individual’s metabolic functioning than individual analyte levels. A low proportion of variation was explained in all multivariate models, supporting the use of universal algorithms in newborn screening and suggesting the need for further large scale empirical research targeted at previously unaccounted for perinatal factors such as birth stress.

Newborn screening programs measure analyte levels in neonatal blood spots to identify individuals at high risk of disease. Carnitine and acylcarnitine levels are primary markers used in the detection of fatty acid oxidation disorders. These analytes may be influenced by certain pre/perinatal or newborn screening related factors. The primary objective of this study was to explore the association between these characteristics and levels of blood carnitines and acylcarnitines in the newborn population. The study was composed of two parts: a systematic review and a clinical database analysis of existing newborn screening data. The systematic review results suggested considerable variability across studies in the presence and directionality of associations between analyte levels and birth weight, gestational age, age at time of blood spot collection, type of sample, and storage time. Sex was not significantly associated with carnitine or acylcarnitine levels in neonatal blood. We identified a need to more fully investigate a potential interaction between gestational age and birth weight in regard to analyte levels. The secondary data analyses indicated a statistically significant relationship between analyte levels and all perinatal / infant and newborn screening related factors of interest, but effect sizes were generally small. The interaction between gestational age and birth weight was significant in all models; when further explored through graphical analysis with conditional means, extremely premature neonates stood out as having distinct analyte patterns in relation to birth weight. Variation in the ratio of total acylcarnitine to free carnitine was better accounted for by the perinatal and newborn factors than was variation in any individual carnitine or acylcarnitine, indicating that proportions of carnitine and acylcarnitines may be more important in understanding an individual’s metabolic functioning than individual analyte levels. A low proportion of variation was explained in all multivariate models, supporting the use of universal algorithms in newborn screening and suggesting the need for further large scale empirical research targeted at previously unaccounted for perinatal factors such as birth stress.

Increasing time trends in the recorded incidence of childhood cancer have been reported in many different settings. The extent to which these trends reflect real changes in incidence, rather than improvements in methods for diagnosis and registration, is controversial. Using data from the National Registry of Childhood Tumours (NRCT), this thesis investigates time trends in cancer diagnosed under age 15 in residents of Britain during 1966-2005 (54650 cases), and considers potential sources of artefact in detail. Several different methods are used to estimate completeness of NRCT registration. The history of methods for diagnosis and registration of childhood cancers in Britain is described, and predictions are made for effects on recorded incidence. For each of the 12 main diagnostic groups, Poisson regression is used to fit continuous time trends and ‘step’ models to the annual age-sex-standardised rates by year of birth and year of diagnosis. Age-specific rates by period, and quinquennial standardised rates for diagnostic subgroups, are shown graphically. For three broad groups (leukaemia, CNS tumours and other cancer), geographical variation is compared by period of diagnosis. The results of these analyses are discussed in relation to the predicted artefacts. The evidence for a positive association between affluence and recorded incidence of childhood leukaemia is briefly reviewed. A special form of diagnostic artefact, the ‘fatal infection’ hypothesis, is proposed as an explanation of both this association and the leukaemia time trend. This hypothesis is examined in a novel test based on clinical data. The recorded incidence of childhood cancer in Britain increased in each of 12 diagnostic groups during 1966-2005 (from 0.5% per year for bone cancer to 2.5% for hepatic cancer, with 0.7% for leukaemia). Evidence presented here suggests that these increases are probably artefacts of diagnosis and registration. The potential implications for epidemiological studies of childhood cancer should be considered.