The Infant Health Study - Promoting mental health and healthy weight through sensitive parent-ing to infants with cognitive, emotional, and regulatory vulnerabilities: protocol for a stepped-wedge cluster-randomized trial and a process evaluation within municipality settings.

Background: Child mental health problems are a major public health concern associated with poor mental and physical health later in development. The study evaluates a new community-based intervention to promote sensitive parenting and reduce enduring mental health problems and unhealthy weight among vulnerable infants aged 9-24 months.
Methods: We use a step-wedge cluster randomized controlled trial design conducted within a home visiting program offered by community health nurses to infant families in Denmark. Sixteen municipalities are randomly
allocated to implement the intervention starting at three successive time points from May 1, 2022 to January 1, 2023. A total of 900-1000 families will be included. A standardized program, Psykisk Udvikling og Funktion (PUF), is used to identify infants with major problems of eating, sleep, emotional or behavioral regulation or developmental problems.
The intervention builds on the Video-Feedback Intervention to Promote Positive Parenting (VIPP) program, adapted to the PUF-context and named the VIPP-PUF. Children will be followed up at ages 18 and 24 months. Primary outcome measure is the Strengths and Difficulties Questionnaire (SDQ) at child age 24 months. The other outcome measures include body mass index z-scores, the Ages and Stages Questionnaire Social-Emotional (ASQ:SE2); the Child Behavior Checklist (CBCL 1½ -5); Eating behavior Questionnaires; the Being a Mother-questionnaire (BaM13); the Parental Stress Scale (PSS); and the WHO-5 well-being index (WHO-5). Data on child and family factors are obtained from National registries and the Child Health Database.
Quantitative measures are applied to examine the effectiveness of the VIPP-PUF intervention and the implementation process. Qualitative measures include interviews with CHNs, parents and municipality stakeholders to explore factors that may influence the adherence and effectiveness of the intervention.
Discussion: The study examines a service-setting based intervention building on the promotion of sensitive parenting to vulnerable infants. We use a mixed methods approach to evaluate the intervention, taking into account the influences of COVID-19 pandemic running since March 2020. Overall, the study has potential to add to the knowledge on the possibilities of prevention within the municipality child health care to reduce the risk of mental health problems and unhealthy weight in early childhood.