Table 1

Inclusion and exclusion criteria

Inclusion criteriaExclusion criteria
 At-risk population of parents of infants 0–12 months old in western Organisation for Economic Co-operation and Development countriesStudies including specific groups such as young mothers (mean age <20 years), divorced parents, parents with mental health problems such as schizophrenia and abuse, and children born preterm, at low birth weight or with congenital diseases
 Structured psychosocial parenting intervention consisting of at least three sessions and initiated either antenatal or during the child’s first year of life with at least half of the sessions delivered postnatallyInterventions not focusing specifically on parenting (eg, baby massage, reading sessions with child or breastfeeding interventions), and unstructured interventions (eg, home visits not offered in a structured format)
Control group
 No restrictions were imposed. All services or comparison interventions received or provided to the control group were allowed.
 Child development and/or parent–child relationship outcomesStudies reporting only physical development or health outcomes such as height, weight, duration of breastfeeding and hospitalisation
Papers with insufficient quantitative outcome data to generate standardised mean differences (Cohen’s d), ORs and CI
 Randomised controlled trials (RCT) or quasi-RCTsOther study designs such as case control, cohort, cross-sectional and systematic reviews
Publication type
 Studies presented in peer-reviewed journals, dissertations, books or scientific reportsAbstracts or conference papers; studies published in languages other than English, German or the Scandinavian languages (Danish, Swedish and Norwegian)