In recent years awareness of childhood obesity as a clinical and public health problem has increased. However, a number of important issues related to childhood obesity were unclear when this thesis began. The aims of this thesis were as follows: 1. To estimate the prevalence of obesity in British and Iranian children. 2. To assess the strengths and weaknesses of the body mass index (BMI) as a way of identifying obese children/estimating obesity prevalence. 3. To investigate the factors associated with early 'adiposity rebound'. 4. To identify risk factors for obesity in British children. This thesis showed that prevalence of childhood obesity in British and Iranian children was significantly higher than expected and that obesity prevalence in children increased during the 1990s. These results are consistent with reports of increased childhood obesity in the USA, Europe, and some other countries. Using BMI 95th centile as the definition of childhood obesity has moderately high sensitivity and high specificity, though a definition of BMI 92nd centile was shown in this thesis to be optimum. This thesis indicated that the typical age of AR in British children must be sometime between 5-7 years. Further research on the factors associated with timing of AR is recommended. A number of independent risk factors for childhood obesity are identified. Parental obesity, birth weight, fizzy drink consumption, and time spent in the car had the strongest association.

Two studies were performed to detect aetiology of acute diarrhoea in hospitalized children aged under five years in Tripoli, Libya. In the first study, two hundred and thirty-six stool samples were obtained. Of these, 118 were from patients admitted for acute diarrhoeal disease, and 118 age and sex-matched concurrent controls were admitted for other reasons. In the second study, eight hundred and ten stool specimens were collected 405 from patients and the same number from controls. All were admitted to the AIjala Children’s Hospital, Tripoli, Libya. The first study was conducted between August 1st 1997 and 31st October 1997 and the second study was conducted between January 1st 2003 and 31st December 2003. One or more enteric pathogens were isolated from 55.9% of patients and 13.6% of controls in the first study and 68.1 % of patients and 12.6% of controls in the second study. In the first study, the organisms were identified from stool of patients; Escherichia coli 22.9%, rotavirus 15.3%, Campylobacter 7.6%, Proteus 7.6%, Klebsiella 4.2%, Entamoeba histolytica 4.2%, Cryptosporidium 2.5% and Giardia lamblia 1.7%, Salmonella was not isolated in both studies, because not growth on ordinary media were used (MacConkey agar and Blood agar) but usually growth on Salmonella-Shigella medium where not used. In the second study, enteropathogens identified were: rotavirus 30.4%, Escherichia coli 16.5%, Entamoeba histolytica 12.5%, Campylobacter 6.7%, Giardia lamblia 3.7%, Cryptosporidium 3.2%, Klebsiella 2.9%, Proteus 2.2%. Libyan children under six months of age were the most susceptible to acute diarrhoea requiring admission to the hospital. This was remarked in 46.6% of patients in the first study and 43.2% in the second. Exclusive breast feeding in Libyan children was of a very low percentage. In the first study it was 19.5% and in the second 29.1%. Children use dummies were about 3 times more at risk of diarrhoea than the non users in the first study (OD: 5.95,95%, CI: 1.120-2.37, p<0.001) and RR: 3.1 and (0: : 2.986ý 95%. Cl: 2.13-4.16, P<0.001) and RR: 23 in the second, this fell to children being twice as much at risk of contracting diarrhoea. Watery stool was the most common stool consistency of patients in both studies. Fever was the most common clinical feature associated with acute diarrhoea in the two studies (72.9% and 71.6% respectively). Vomiting was present in 51.7% of patients among the first study and 58.3% among the second. Moderate and isotonic dehydration were the most common degree and type of dehydration across both studies. In the second study, Rotavirus peaked during the winter (cold season) while bacteria and parasites peaked during the summer and autumn seasons. API 20E and API Campy were used to identify bacterial isolated by cultures and the number of confirmed cases decreased from 142 to 112 samples. Polymerase Chain Reaction was adopted in the second study to confirm detection of Campylobacter spp. these were identified by API Campy technique, where all Campylobacter spp. were identified as the same as detected by API Campy and for 24 samples.

There is evidence that sedentary behaviour and breaks in sedentary time, independent of physical activity levels, influence human health. In order to explore this relationship, accurate and validated measurement instruments are required. Such tools are also required for exploring the effects of factors such as the differences in sedentary behaviour between groups, e.g. overweight/obese vs. healthy weight children. One promising instrument for making such measurements is the activPAL™ monitor. This is an event-based accelerometer with inbuilt inclinometer, and it may be more accurate for the measurement of sitting time and breaks in sitting than earlier instruments. An important setting in the monitor depends on the time required to define a new posture – the minimum sitting/upright period (MSUP). At present, the optimum activPAL™ MSUP setting is not known, particularly for children, who are likely to change posture faster than adults. This thesis includes four studies: Study 1 (Chapter 3): Using the activPAL™, we investigated the effect of variations in MSUP on total sitting time and breaks in sitting. Methods: Study 1a: In this in vitro experiment, the activPAL™ monitor was turned from a horizontal position to a vertical position manually (by hand) to simulate 5 sitting bouts. The length of the sitting time was varied from 1s to 10s. The number of the true events (i.e. 50) and the data from the activPAL™ (the number of sitting bouts for each bout length) was compared and represented in a graph. Study 1b: in data collected from children in a free-living environment (23 children (mean (SD) age 4.5yrs (0.7)) who wore the activPAL™ (24 hr/d) for 5-7d), we varied the setting of the MSUP. For each child, we calculated the following measures of sitting behaviour: volume (total time in sit/lie postures); number of breaks (number of sit/lie to stand transitions); number of sitting bouts (number of discrete periods spent sitting/lying); and pattern of accumulation of sitting (represented by accumulation curves and fragmentation index). We first studied the activPAL™ using the default setting of 10s MSUP, and then reduced this to 5s, 2s, and 1s. Results: Study 1a: the analysis software did not count sitting bouts of a shorter duration than the user defined MSUP in the new posture. For example, the sitting bouts with a period less than 10s were not counted when we used the activPAL™ setting of 10s MSUP. Study 1b: Comparing settings of 10, 5, 2, and 1s, there were no significant differences in total sitting time (6.2 hr (1.0), 6.3 hr (1.0), 6.4 hr (1.0), and 6.3 hr (1.6), respectively) between settings, but there were significant increases in: the apparent number of breaks - 8(3), 14(2), 21(4), and 28 (6)/hr) total number of bouts (118(18) vs 382 (80)); and Fragmentation Index (19.3 (3.7) vs 61.6 (16.4)), with a reduction in 50% bout length from 80s (14.7) to 42s (7.7) at 10s and 1s setting, respectively. Conclusion: With the activPAL™, breaks in sitting, but not total sitting time, are highly sensitive to the setting of the MSUP. Additional studies will be required to confirm these findings and to define the most appropriate MSUP for different age groups. Simple measures can characterise sitting behaviour in young children using the activPAL™. Study 2 (Chapter 4): Posture transitions are likely to be much more rapid in young children than in adults. We investigated the optimum activPAL™ setting of MSUP to define a change in posture for measurement of sitting time and breaks in sitting (not previously known). We evaluated the validity of different minimum event duration settings against direct observation as the criterion method. Methods: In a convenience sample of 30 pre-school children (mean age 4.1yrs (SD 0.5)), we validated the activPAL™ measures of sitting time and breaks in sitting at different MSUP settings against direct observation. Results: In comparison with direct observation, a 2s setting had the smallest error relative to direct observation (95% limits of agreement: -14 to +17 sitting bouts/hr, mean difference 1.83, p = 0.2). Conclusion: For pre-school children, 2s appears to be an appropriate MSUP to define breaks in sitting using the activPAL™. Study 3 (Chapter 5): The identification of risk factors for obesity is considered key to obesity prevention. Differences in time sitting compared to standing have been observed in obese and non-obese adults. Whether such differences are present between obese and non-obese children has not yet been examined. In a pilot study, we investigated differences in sitting behaviour between overweight/obese and healthy weight children. Methods: Overweight/obese children were recruited from weight management and dietetic clinics, the Active Children Eating Smart programme, and from three primary schools, while healthy weight children were recruited from schools. The participants wore the activPAL™ (24 hr/d) for 5-7d. During waking time, the time spent sitting, number of sitting bouts, the 50% and 90% sitting bouts length, and the Fragmentation Index were measured in both groups using the activPAL™ with a 2s MSUP setting. Results were available for 26 healthy weight children (mean age 6.4yrs (SD 0.9), median BMI Z-score 0.04 (range -3.24 - 0.66)) and 13 overweight/obese children (mean age 6.4 yrs (SD 0.9), median BMI Z-score of 1.38 (range 1.14 - 3.10). Results: In healthy weight children during the waking hours, the mean (SD) percentage of waking time spent sitting was 53.0 % (6.4) representing 6.8 hrs (0.9) per day; mean (SD) total number of sitting bouts per day was 280 (65). The median (range) of 50% and 90% of sitting bouts were ≤50.0s (40.0-50.0) and ≤3.5 min (2.0-6.0), respectively. The mean (SD) Fragmentation Index was 42.1(12.7). In the 13 overweight/obese children, the mean (SD) percentage of waking time spent sitting was 52.4% (5.2), representing 6.9 hrs per day (SD 0.8). The total number of sitting bouts was 284 per day (66). The median (range) of 50% and 90% of sitting bouts length were ≤50.0s (40.0-50.0) and ≤3.5 min (3.0-6.0), respectively. The mean (SD) Fragmentation Index was 41.5 (9.6). Conclusion: Both healthy weight children and overweight/obese children in this study spent the majority of their waking time sitting. Furthermore, there were no significant difference in the sitting time, number, or duration of sitting bouts and the Fragmentation Index between the two groups in this study. Study 4 (Chapter 6): Previous studies have shown differences in the total sedentary time between boys and girls using accelerometers where sedentary behaviour was defined as low movement or low energy expenditure. In the present study, we examined whether there were also differences in breaks in sitting time. Methods: A convenience sample of 62 (32 girls: 30 boys) free-living healthy children (mean age 5.8yrs (SD1.3)) was recruited from nurseries and schools in Glasgow and Edinburgh, Scotland, who each wore the activPAL™ monitor continuously for 5–7 days. For each child, the components of sedentary behaviour were measured. Results: The percentage of waking time spent sitting was significantly higher in girls, the mean (SD) (54.4% (5.6)) compared to boys (50.9 (5.6)), (2-sample t-test, p-value <0.02). The total sitting time in girls vs. boys respectively per day was 6.9 (0.8) vs. (6.5) (0.9), (p-value <0.08). There were no significant differences in the number of sitting bouts, Fragmentation Index, or in 50% and 90% sitting bout length between girls and boys. Conclusion: This study suggested that girls spend more time in sitting than boys. However, there were no significant gender differences in the number or duration of sitting bouts. Summary Conclusion: These studies have validated the activPAL™ as an instrument for measuring breaks in sedentary time in young children, and have established appropriate settings for making accurate measurements in this age group. Using these monitors to explore differences between obese and non-obese children, and between boys and girls, we found that, while there were differences between boys and girls in the total sitting time, there were no differences in the number of breaks between girls and boys, or between obese and non-obese children. These studies suggest that the activPAL™ may be useful to identify between group differences in sitting time and sitting fragmentation in future studies.

The aim of this research was to provide a detailed description of emotional expression in infants, with and without disabilities. 30 typically-developing infants (aged four to five-and-a-half months)were video-recorded in four situations: immunisation, oral polio vaccination, social play and response to a surprise toy. These were designed to elicit a range of emotional behaviours. 20 infants with congenital, developmental disabilities of varying aetiologies were matched on developmental age and filmed in the same situations. Facial expressions were coded using the Maximally Discriminative Facial Movement Coding System (Max) (Izard, 1983) and emotional behaviour during interaction with Monadic Phases (Tronick, Krafchuk, Ricks, Cohn & Winn, 1980). Infants with disabilities showed fewer expressions of pain involving the whole face, and more expressions resembling blends of pain with fear, than typically-developing infants. This was due to several of these infants drawing back the mouth into a horizontal-stretch, rather than opening it fully. There was no group difference in time to respond to needle penetration with a pain expression, although median response time was higher for infants with disabilities. Both groups of infants had negative correlations between reaction time to pain and intensity of pain expression and time to recovery, indicating that infant emotion systems are integrated and coordinated with other behavioural systems. Expressions of infants with disabilities were also more fleeting and they showed reduced muscle movement in the upper-face and unconventional movements in the mid-face. They also showed fewer joy and interest expressions using the whole face, and more uncodeable expressions. Carers and female students were shown pictures of the infants' facial expressions and asked to describe the emotions they showed. There was no difference between carers and students, in accuracy of discriminating expressions of typically-developing infants, supporting claims of innate recognition of facial expressions. Expressions of sadness, fear, joy and surprise of infants with disabilities were discriminated less accurately than those of typically-developing infants. All expressions of infants with disabilities were perceived as giving significantly less intense signals than those of typically-developing infants. There were some systematic errors in judgement, with anger and pain, fear and sadness and interest and surprise expressions being mistaken for each other. This was explained in terms of morphological similarities between these expressions. Carers of infants with disabilities were more accurate at judging their own infant, but otherwise no more accurate than other judges. Coding of interactive behaviour revealed that infants with disabilities showed significantly more social attend and avert, and less social play, object attend and object play, than typicallydeveloping infants. These differences were attributed to delayed changes in functional use of eye contact and greater need to use aversion as a mechanism for regulating arousal in infants with disabilities. Carers of infants with disabilities showed less social play than those of typicallydeveloping infants. In these dyads, there was some evidence of lower frequency of agreement between infant and carer behaviours. This study provides a more comprehensive description of emotional behaviour, and involves a smaller range of developmental ages and a wider range of emotion-eliciting situations, than previous studies. The findings are useful for informing interventions for infants with disabilities and their carers.

Background: Effective delivery of dental services must be based on reliable information regarding the prevalence and severity of disease in the target population. Evaluation of the various factors known to influence the severity and progression of disease is essential for health policy makers to promote oral health resources and address oral health needs. Objective: The overall aim of this research is to describe the situation of dental caries and investigate the associations of level of oral health knowledge, teeth irregularity, BMI and other life style variables (TV viewing, internet use, passive smoking and dietary habits) with dental caries, including the impact of socio-demographic factors amongst school children in Qatar. Materials and methods: A cross-sectional study was conducted in Qatar from October 2011 to March 2012. A total of 2,113 children aged 12-14 years were randomly selected from 16 schools from different areas. Clinical examination was conducted by three calibrated examiners using World Health Organization criteria for diagnosing dental caries. Teeth irregularity was determined clinically according to a method described by Björk et al (1964). A pre-tested and structured questionnaire was used to assess oral health knowledge and life style data. Data analyses were performed. Results: The mean decayed, missing and filled teeth index values was 4.62 (±3.2), 4.79 (±3.5), and 5.5 (±3.7), respectively, for the 12, 13 and 14 year old children. The caries prevalence was 85%. The mandibular incisors and canines were least likely to be affected by dental caries, while maxillary and mandibular molars were the most frequently attacked by dental caries. Of the total sample, only one quarter reported a high level of oral health knowledge. There were more incidences of teeth crowding (44.1%) than teeth spacing (9.5%). The overall prevalence of underweight, overweight, and obesity was 5%, 10%, and 5% respectively. Almost half of the children spent > two hours watching television and 46% spent > two hours using internet. Approximately 35.8% of children had exposure to passive smoking. Concerning dietary habits, 99.4% of children consumed sugar containing snacks in between meals. Approximately 65% consumed sugar containing snacks within one hour of bed time. Almost 49.1% skipped eating breakfast regularly and 22.7% skipped eating lunch regularly. Around 83.8% consumed diary snacks in between meals. Overall, 74.2% drank tea in-between meals and 80.1% chewed gum in-between meals. All variables were affected by socio-demographic factors, but significant differences were found in female children in that they were more at risk to dental caries than male children. Also, children who resided in semi-urban areas were more at risk to dental caries than children who resided in urban areas. The occurrence of dental caries is significantly associated with the level of oral health knowledge, teeth irregularity, and other life style variables. Conclusion: The need to reduce sedentary behaviors and to promote a more active and healthy lifestyle is becoming increasingly essential in Qatar. Implementation of a community-based preventive oral health programs on a healthy diet and practices of adequate oral hygiene should be promoted in schools through integration into the school curriculum and services to combat the growing problem of dental caries.

This thesis comprises of three papers. The first is a literature review that focuses on the positive impact on parents caring for a child with an intellectual disability. Fourteen themes pertaining to positive impact are derived from papers and the two main measures used to assess positive impact are The Kansas Inventory of Positive Perceptions and The Positive and Negative Assessment Scale. The relationship between positive impact of caring and parental wellbeing is explored. Wellbeing is raised when there are positive perception of caring. The empirical paper explores the relationship between parental stress, challenging behaviour and characteristics of autism spectrum disorder. When people with autism spectrum disorder show challenging behaviours, characteristics of adaptive functioning, pleasure and interest, and reciprocal social interaction are lower and impulsivity is heightened in comparison to people showing no challenging behaviours. Age also differs between groups. Negative correlations between adaptive functioning, pleasure and interest and social reciprocal interaction and parental stress are found. There is a positive correlation between impulsivity and parental stress. Impulsivity is the only predictor of stress. The third paper is a public domain briefing document, which gives an overview of the literature review and empirical paper for dissemination to the general population.

Following recent reform to special educational needs (SEN) guidance and legislation in England, the introduction of the education, health and care (EHC) needs assessment process has resulted in a considerable change in the statutory support system for children with significant SEN. To date, limited research has been conducted to explore perceptions of the EHC process. This research used a multiple nested case study design to explore the perceptions of key individuals – parents, school staff and educational psychologists – about the purposes and experiences of the EHC process. Participant views were collected using semi-structured interviews and analysed using thematic analysis. A range of purposes for the EHC process were identified including; creating a shared understanding of need, facilitating planning and support, protecting children with SEN and promoting progress. Participants reported varying experiences of collaboration during the assessment phase and outcomes following the issuing of the plan. Key factors related to perceptions of success for the EHC process included; values and existing practice, knowledge and access to support and resources. Possible implications for educational psychology practice are discussed through consideration of the practical wisdom, or phronesis, drawn from these findings.

Today, increasing numbers of children and young people (CYPs) live with chronic health conditions. A fact reflected in recent UK legislation which highlights the necessity of supporting these CYPs to fully access education. This study explores the experiences and perspectives of children and young people with chronic conditions (CYPCCs) regarding hospitalisation and hospital school. A narrative methodology was selected to explore the experiences of five hospitalised CYPCCs (aged 12 to 16 years) in addition to the meanings they ascribed to these experiences. Findings contribute important insights into CYPCCs' experiences of hospitalisation in relation to the following family, personal growth, health-related identity, relationships, coping, unpredictability and uncertainty and medical intervention and physical pain. This research makes a unique contribution to the field, in relation to the substantive topic (how CYPCCs perceive educational experiences in hospital settings) and the original application of a narrative research methodology. I argue the necessity for professionals to recognise CYPCCs as a potentially vulnerable group. Ethical issues concerning access to hospitalised CYPCCs for research purposes are highlighted and the value of narrative research with CYPs is endorsed. Implications for professional practice and research are discussed which seek to improve the educational opportunities, experiences and outcomes for CYPCCs.

I investigated the role of genetic, environmental and intrauterine factors in child development using data from two large twin studies; the East Flanders Prospective Twin Survey (EFPTS) and the Twins and Multiple Births Association Heritability Study (TAMBAHS). An association between birth weight and child development has already been established. Potential associations between other factors of the intrauterine environment and child development were investigated in this thesis. Heritabilities of the umbilical cord, IQ, temperament and behaviour problems were estimated. Fetal characteristics, such as birth weight, placental weight and morphology, umbilical cord knots, length and insertions were investigated in relation to cognitive development in the EFPTS study. The impact of maternal pre-pregnancy weight on temperament and behaviour problems was examined in the TAMBAHS study. High heritability estimates were observed for certain dimensions of the umbilical cord, temperament and IQ; for behaviour problems, genetic, shared and non-shared environment were important. Low birth weight and cord knotting was associated with lower IQ; an association was observed between maternal overweight and children aggressive behaviour. The results are discussed in the context of the Developmental Origins of Health and Disease (DOHaD) hypothesis, highlighting the role of the intrauterine environment in child development.

Background: Childhood obesity is increasing rapidly in China. However, research into environmental contributors to the problem is limited. Formative research that informs theoretically based prevention interventions is also lacking. Objectives and Methods: To inform the development of obesity prevention interventions among urban Chinese primary school students by: 1.exploring perceived factors contributing to obesogenic behaviours (17 focus groups and 4 interviews, n=99 including 42 males), 2. exploring preferred components and delivery strategies for future preventive interventions (17 focus groups), 3. examining the relationship of family and neighbourhood environmental factors, to child weight status as well as related dietary and physical activity behaviours (cross-sectional study, n=497). Results: Inter-related social, historical, regulatory, policy, knowledge and economic factors emerged as factors influencing attitudes, social norms and perceptions of control in relation to obesogenic behaviours. Among those, grandparents emerged as a dominant but relatively easy- to- modify theme. In parallel, the presence and role of grandparents were significantly correlated with child weight status and snacking behaviour. Conclusions: The family environment has important influences on childhood obesity and obesegenic behaviours. Drawing on the overall findings, potential targets, components and delivery strategies are discussed using a Social Marketing framework for future prevention intervention.