Mental health problems and overweight often co-occur, they have their origin in early childhood and new research evidence suggest a key role of cognitive, emotional and behavioral regulation in the early developmental trajectories and points to the benefits of intervention in infancy that builds on strategies of sensitive parenting.

The research group behind this project has developed the PUF program (PUF: In Danish: 'Psykisk Udvikling og Funktion') to target infants' mental health and development within the settings of community health nurses. Still, measures are lacking that address the infants most vulnerable regarding the development and progression of mental health problems and overweight.

In this project, we develop and test a new intensified intervention to address major cognitive and regulatory vulnerabilities identified at child age 9-10 months and adapted to the settings of community health nurses. The intervention is created as an add-on to the PUF-program, using an evidence-based method to promote sensitive parenting, the Video-based Intervention to Promote Positive Parenting (VIPP). The new intervention VIPP-PUF comprises six therapeutic sessions delivered by the community health nurse during home visits over a three months period. The intervention builds on teaching the health nurses to promote parents' sensitivity to meet the infants' cognitive and regulatory vulnerabilities, and it takes in account the needs of psycho-socially disadvantaged families.

The Infant Health project is conducted in sixteen municipalities across Denmark. We use the Intervention Mapping approach as the study frame and integrate the best practice of community health nurses. The efficacy of the VIPP-PUF intervention is examined in a randomized controlled step-wedge design, in which approximately 1.000 children are followed up to the age of 24 months.

The VIPP-PUF intervention is hypothesized to reduce mental health problems at ages 24 months among infants with high levels of cognitive and regulatory problems at age 9-10 months, (primary outcome). Also, it is hypothesized that among children with high levels of cognitive and regulatory vulnerabilities at age 9-10 months, adding the VIPP-PUF intervention to treatment as usual at age 9-10 months, will reduce infants' cognitive and regulatory problems; promote healthy weight development; reduce parents' experiences of stress; promote sensitive parenting and promote parents' feeling of competence and relatedness.

BACKGROUND Childhood mental health problems and overweight are highly prevalent, and they have severe long-term prognoses regarding mental and physical health, social functioning, and premature death.

The majority of child mental health problems have their origin within the first years of living with increased risk in infants from families of psycho-social disadvantage, and in infants with perinatal adversities and cognitive and psycho-motor difficulties. Problems of eating, sleep, and emotional and behavioral regulation may predict mental health problems and disorders and persistent dysregulation trajectories are associated with emotional- and behavioral problems, eating problems and attention deficit hyperactivity disorder, ADHD. Early parent-child relations and the quality of parenting has a key position in the risk mechanisms.

The risk of overweight is highly increased in children, who are overweight in infancy. Psycho-social risk factors are similar to those of mental health problems, e.g families of psycho-social disadvantage with risk mechanisms including gene-environment interaction, maternal feeding pattern; and higher risk among obese parents to introduce high energy and fat foods very early and having impaired responses to the infant's hunger and satiety cues.

Mental health problems tend to precede the development of overweight in childhood. Potential mechanisms include cognitive vulnerability of inhibitory control/reward, sensitivity and sustained attention, leading to impulsive eating and difficulties in delaying gratification. Infants' problems of emotional regulation and problems of maintaining an affective homeostasis confronted with stress-full experiences may result in emotional eating characterized by pathways of physiological stress responses and reward, in which appetite and attraction to sweet and fatty foods is considered to develop through poor emotional regulation and lower inhibitory control.

Prevention of mental health problems and overweight has to start early and combine universal strategies and targeted interventions to reduce risk exposures, optimize parenting and promote child development and a healthy weight development. The combination of universal approaches and specific intervention to target the most vulnerable children is the most effective way to the reduce the population load of childhood mental health problems and overweight.

Strategies to optimize parenting of infants at risk of mental health problems and overweight have to build on measures that promote parent's sensitivity, understanding and careful handling of the child's regulatory, emotional or cognitive vulnerabilities.

Home-visiting programs that are embedded in the general child health surveillance have unique possibilities of reaching the entire infant population and integrate specified interventions to infants and parents of particular needs.

The general child health surveillance in Denmark includes scheduled home visits to all infant families offered by community child health nurses, CHNs. The CHNs measure the child's weight and overall health and development, and they give parents advice regarding the care of the infant. In about 20% of infant families, the CHNs extend their services to target particular problems and needs, e.g regarding problems of eating and sleep, or the parent-child relation. Until recently, however, no standardized measures have been available to specifically address infants at risk of mental health problems and overweight. We have previously explored the possibilities of prevention within the municipality child health surveillance and identified potential predictors and mediators of developmental psychopathology, and a window of opportunity regarding intervention towards infants' cognitive and regulatory vulnerabilities at child age 9-10 months. We have developed, validated and implemented a standardized measure to help the CHNs to identify mental health vulnerabilities. By this measure, the CHNs combines information from parents and her own observations during the home-visit to make a final conclusion about the child's development and functioning within eight areas of child mental health: sleep, feeding and eating, emotional regulation, motor development, attention and concentration, curiosity and interests; contact and communication and language development. Validation studies have shown that children who have three or more problems within these areas have a significantly increased risk of mental health problems. The PUF-program was developed as a basic approach to help CHNs to guide their actions to address the problems identified at ages 9-10 months within the existing service settings. Still, the PUF-program do not include specified intervention to infants with high level of cognitive, regulatory and emotional problems, leaving these children behind with an increased risk of developing mental health problems and overweight.

AIMS The study aims to develop and test an intervention to promote sensitive parenting of infants with mental health vulnerabilities identified by CHNs at age 9-10 months and to be feasible within the settings of the municipality child health surveillance. Parents' resources are a particularly important regarding interventions to target child mental health and healthy weight, and it is a specific aim of the study to address the needs of parents of psycho-social adversities and how the intervention works for the most vulnerable families. The overall aim is to examine the feasibility, fidelity, and the effectiveness of the intervention delivered to parents of infants with major cognitive, regulatory and emotional problems with child mental health and weight development at child ages 18 and 24 months as the primary outcome.

METHODS The development, implementation and evaluation of the intervention is guided by the Intervention Mapping approach, guides for development of complex interventions from the UK Medical Research Council and the RE-AIM-method.

The Infant Health Study includes four work-packages (WPs), the WP 1: Project planning and management; WP 2: Creating the intervention; WP 3: The efficacy study; WP 4 the process evaluation, including an evaluation of what works for the vulnerable families, and a Pilot study prior to WP3 and WP 4.

The study is anchored in the settings of CHNs in a collaboration of municipalities who join a validated clinical database and among those municipalities who have implemented the basic PUF-program one year prior to study start. These municipalities are overall representative of the Danish population regarding key background characteristics.

The study is located at the National Institute of Public Health; and study methods make use of the particular opportunities of epidemiological research in Denmark due to a civil registration system which follows all citizens are throughout life and the possibilities of valid tracking of children, parents and background information from Danish population registries.

DESIGN The stepped wedge cluster randomized design is chosen because it is more feasible to randomize at the municipality level as compared to the level of the individual child or CHN. For practical reasons, all municipalities cannot be trained at the same time but have to be split into three groups, and with the stepped wedge design, we utilize this and randomly allocate the 16 participating municipalities to the time at which their health nurses have been trained, and at which they start offering the intervention to families. Also, with the stepped wedge design, spill over is reduced by the randomization of clusters as compared to individual randomization, and interventions are introduced in a stepwise manner to all participating clusters (municipalities in this case) which encourages participation for those who would otherwise have been randomized to the control condition. Further, with the stepped wedge design control families are recruited in the early phases of the trial, which enhances the recruiting of a control group with the level of usual care offered at the beginning of the trial. In the control period no participants receive intervention and sequential random crossover to the intervention cannot be reversed.

According to the randomization of municipalities, all children assessed to have high levels of cognitive and regulatory problems at age 9-10 months will function as controls and receive care as usual from Step 0 until the municipalities initiate the intervention in Step 1- 3, respectively.

PROJECTPLANNING AND MANAGEMENT (WP 1) A participatory planning group of the principal investigators and the leading CHNs are part of the planning and management of the project. A well-established collaboration with the leading CHNs from the participating municipalities facilitates their function as primary municipality stakeholders in WP 2-4.

The information from our close collaboration with the CHNs is currently updated in WP 1, and taken into account when developing the intervention, and in the strategies necessary to ensure fidelity and deliver valid results for the efficacy trial.

PREPARING THE INTERVENTION (WP 2) The overall goal is to create an intervention to function as an add-on to the basic PUF-program within the municipality settings in order to promote sensitive parenting of infants with high levels of cognitive and regulatory problems.

Among measures to promote parenting of vulnerable infants, the Video-feedback Intervention to Promote Positive Parenting, VIPP takes a strong position in being effective in the reduction of child problems, also in families of psycho-social disadvantage, including maternal eating problems. Research in effective obesity prevention in early childhood is scarce, but the available evidence points to infancy dysregulation and parenting as potential targets.

Initially, a group of CHNs are educated in the original VIPP method to enable them to contribute to the adaptation of the VIPP into the novel combined VIPP-PUF intervention. Further, these CHNs participate in the pilot testing of the VIPP-PUF, and they function as co-trainers and supervisors of the next generation of CHNs educated in the VIPP-PUF during the project period.

RECRUITMENT All children in the population are offered home visits, and more than 85% attend at the home visits at child age 9-10 months. Parents of children who have three or more problems at the PUF assessment are informed about the study by the CHNs, and via written folders and information on the study home page. If the parents agree to participate, they are afterwards invited to participate by e-post or by letter. Parents make their final agreement for participation by answering the web-based questionnaires at the study website. Parents who have difficulties in completing the questionnaires are offered assistance from the CHN. All participating parents get a gift certificate of about 27 euro after answering the questionnaires.

In the control phase of the study, the CHNs deliver their service and care as usual. In the intervention phase, the CHN offers parents the VIPP-PUF-intervention.

Inclusion Criteria:

• Three or more PUF problems at the PUF

Exclusion Criteria:

• Severe mental or physical illness or handicap.
• Not Danish or English speaking parents