Key research question This project addresses the following key research question: What are the short and long term effects on child and family outcomes of a universal intervention delivered by a Health Visitor addressing the newborn´s behavior in a shared observation with the parents (NBO)? The aim is to enhance the parent's sensitivity to their infants' unique capacities and thereby create an early parental understanding for the individual infant's strengths as well as its needs.

Hypothesis concerning main outcomes

Universal Health Visiting with facilitation of the early relationship building introduced by the NBO to an intervention group of new families will- when compared to a control group of new families who receive health visitor support as usual:

• Improve sensitive responsive parenting to the infant's behavior, needs for feeding and comfort, and rise understanding of parental influence on the infants' self-regulatory capacities
• Increase parental confidence and reduce experiences of stress and symptoms of depression among new mothers and fathers
• Improve the infant's self-regulatory capacities regarding sleep, crying, feeding and engaging in social interactions, being more cooperative
• Enhance the sensitive early parent/infant relationship
• Improve exclusive breastfeeding duration and delay introduction to solid food

Method The project is formed as a community based randomized trial. The complexity in community based intervention research is the existence of two target groups, in this case: 1) the primary study population of new parents that receive the supportive intervention and 2) the secondary study population of Health Visitors that deliver the supportive intervention. The complication of catching the effects in a universal approach will be addressed through a variety of outcomes that capture both the aspect and the development of the infant, the mother and the father and the interactions.

Recruitment and randomization Four medium-sized municipalities will join in the trial. To avoid side-effects the districts of the Health Visitors in the participating municipalities will be regarded as clusters. A restricted randomization procedure is decided to achieve balance in the two study arms because of a relatively small number of clusters (n=17) with huge differences in birth rate. The criteria for the restricted randomization is a geographical balance with all participating municipalities represented by both intervention and comparison districts and a numerical balance with expected number of births attempted between the intervention and comparison group. An external data manager performed the entire procedure.

Study population The primary study population is formed by new families, mothers and fathers and their infant/s. Substantiated in that we are operating with a community based universal intervention with no side effects and we seek to measure the effect in a natural population we will have no exclusion criteria except parents or infants affiliated to special treatment elsewhere.

In the study population of new parents there will be subgroups: First time parents will represent around 40 %, around 6 % will have given premature birth, 2% twin birth, 10-14% of the mothers and 7-8% of the fathers will suffer from birth depression in the postnatal period, and 7-20% will have a cultural background other than Danish depending on geographical area.

A subgroup of 100 first-time mothers in each group of intervention and comparison are drawn consecutively among responders for video recording in the middle of the project period after specified characteristic criteria with regard to first-time-, depressed- and given premature birth.

Data and data-collection Data will be collected from two sources: (1) self-reported data from the new parents collected via questionnaire; (2) observational data from video recordings, Infant CARE-Index. Questionnaire data will be delivered and collected though an internet based system. Participating mothers and fathers will receive separate questionnaires at 1-2 weeks postpartum (baseline data), 3 months postpartum, 9 months follow-up, 18 months follow-up. Videos are recorded at 3 months post-partum (corrected age for premature infants) with 3 minutes of unstructured time together; (Infant CARE Index). All data will be linked via the Danish Personal Register (CPR) identifier. To minimize bias introduced by data collection, data will be collected in the same way and with the same timing in the intervention and comparison groups.

Data Analysis Intention to treat analysis will be used to detect the effect of the community based intervention where motivation and participation may vary in both the primary and secondary study population. Supplemental analysis will be performed to identify an intervention effect for subgroups and marginal groups of parents according to parity, preterm delivery, and depression symptoms.

Inclusion Criteria:

The primary study population is formed by new families, mothers and fathers and their newborn/s. Substantiated in that we are operating with a community based universal intervention with no side effects and we seek to measure the effect in a natural population we will have no exclusion criteria

Exclusion Criteria:

• except parents or infants affiliated to special treatment elsewhere.