Short summary

The Bloom Study aims to promote healthy weight development among infants and toddlers in Denmark. The intervention is initiated during pregnancy and commence until child age of 30 months. The study is evaluated within a cluster-randomized controlled trial with 22 municipalities randomly allocated to intervention (11 municipalities) and control (11 municipalities) with a thorough evaluation of the effectiveness, process, implementation, and cost-effectiveness.

Rationale

Child overweight and obesity are serious challenges to public health in the 21st century. Overweight and obesity prevalence levels have reached historically high levels, affecting all age groups throughout the life course. In Denmark, 14% of children have overweight or obesity when starting school and 19% when leaving school, with an even higher prevalence level among children in families with low socio-economic position (SEP) and ethnic minority background. Childhood overweight and obesity have significant physical, psychological, and social impacts, such as reduced quality of life by increased risk of various adverse psychosocial outcomes including low levels of well-being, low self-esteem, feelings of sadness, loneliness, nervousness, and depression. Moreover, children with overweight or obesity may experience decreased social participation and are more frequently exposed to bullying. Physiologically, overweight and obesity increase the risk of cardiometabolic diseases, and asthma already during childhood and adolescence. Early intervention is crucial as overweight and obesity established in childhood is difficult to revers, and it is increasingly being recognized that infancy is a window of opportunity for promoting healthy weight development due to identifiable risk factors. Also, early intervention holds the potential to reduce the social inequality in overweight and obesity that starts in infancy but undergo significant development into youth. The aetiology of childhood overweight is complex and not fully understood. It is generally proposed that the development of overweight and obesity in children and adolescents is a consequence of interactions between genetic, behavioural, psychosocial, and environmental factors. Several well-documented risk factors related to food intake and feeding practice, physical activity level and infant motor capability, screen use, and sleep duration and quality are potentially modifiable by interventions implemented during infancy and childhood. Furthermore, there is increasing evidence that various psychosocial aspects including social adversity (e.g., low education, low socio-economic position, poverty, financial insecurity and ethnic minority background) play a significant role in the development of obesity. In a new model for obesity development, Hemmingsson et al. suggest that prolonged social adversity increases the risk of parental chronic stress and psychological strain which in turn contribute to an insecure and disharmonious family environment. An essential component of the model emphasizes the importance of fostering the social and emotional needs of a child through the parent-child interactions, thereby ensuring sensory-rich experiences, secure attachment, and emotional bonding. Failure to meet these needs by parents increases the risk of child insecurity, chronic stress, and negative emotions, which may lead to disrupted energy balance homeostasis, resulting in weight gain and obesity. Following the growing recognition of the need for early primary prevention of overweight and obesity and an enhanced understanding of early risk factors associated with child overweight and obesity, an increasing number of intervention studies have been conducted. However, only five multi-behavioural health center- or home-based randomized controlled trials (RCT) targeting a substantial number of infants and their families have reached complete evaluation. Only few of these trials have shown a small effect on child BMI. The most promising results are seen for the high-dose and home-based programs commenced in pregnancy and extended for a minimum of two years postpartum. Consequently, there is a need for further exploration of the potential of the home setting. It is specifically important to leverage the opportunity thereby given for adapting and tailoring the intervention to the specific needs and circumstances of the individual families. This is not explicitly and in a standardized manner built into the design of the previous studies. Related to this, previous early obesity prevention initiatives have predominantly focused on mothers as the primary recipient of the intervention. This deviates from the contemporary recognition that acknowledge the integral role that fathers/partners play in e.g., child feeding as they are increasingly (especially in Denmark) involved in childcare and household routines and responsibilities. The predominant focus of most interventions has been on nutrition and physical activity. However, recent evidence points to the importance of addressing child sleep, and psychosocial and emotional aspects of parent-child interaction in future interventions. SEP has generally not been a key parameter in the intervention development or implementation, and only few studies have investigated differential effects of the intervention by SEP. While many interventions have adhered to a one-size-fits all approach, it is likely that different target groups (e.g., fathers/partners, families of low SEP, and ethnic minorities) need different modes of delivery. Several of the past interventions lacked integration with existing health service structures, which may have affected implementation and contributed to the observed absence of long-term effects. More comprehensive and multicomponent interventions, co-designed with stakeholders and closely linked to public health practice are needed to address the challenge of childhood overweight and obesity. The lack of solid effects on weight-related outcomes of previous interventions within this field calls for re-evaluation and a commitment to innovative strategies. Therefore, the Bloom Study aims to implement and evaluate a theory- and evidence-based intervention addressing infancy to promote healthy weight development and well-being among children in Denmark The development and final design of the Bloom Study builds on a thorough co-creation process, existing evidence and experiences from earlier interventions and has integrated promising elements to increase the likelihood of positive effects on child healthy weight development. Hereby, the Bloom Study will focus on modifiable risk factors for overweight and obesity in infancy and childhood, including factors that are increasingly recognized but have not yet been tested in large-scale trials. Further, the Bloom Study targets all first-time families, but with a specific focus on reaching families with low SEP and/or ethnic minority background and involvement of fathers/partners. Finally, the Bloom Intervention will be integrated in the existing and well-accepted home-based community health nurse system.

Description of the cohort

Study participants of the Bloom Study is first-time parents and their child living in Danish municipalities challenged by child overweight and obesity.

Data and biological material

The Bloom Study data collection includes a diverse set of data methods: 1) Self-reported questionnaire data from parents and community health nurses, 2) anthropometric measurements to measure child length/height and weight, 3) bio-electrical impedance analysis to measure child body composition, 4) information from national registers, 5) community health nurses' electronic records, and 6) actigraphy to measure child movement and sleep (subsample).

Collaborating researchers and departments

DaCHE - Danish Centre for Health Economics, University of Southern Denmark

• Professor Kim Rose Olsen
• Senior Health Economist Line Planck Kongstad

University of York

• Professor Richard Cookson

Department of Psychology, Center for Early Intervention and Family Studies, University of Copenhagen

• Professor Mette Skovgaard Væver
• Tenure Track Assistant Professor Ida Egemose Pedersen

Section of Health Services Research, Danish Research Centre for Migration, Ethnicity and Health, University of Copenhagen

• Senior Advisor Janne Sørensen