Mid-term effects of a parenting programme on early childhood development and maternal health in Vietnam: protocol for a follow-up of a cluster-randomised controlled trial.

introductionParents are crucial as providers of nurturing care for their children to grow and thrive. A community-based multicomponent intervention for women's health and early childhood health and development was conducted in rural Vietnam, spanning from mid-pregnancy through the first postpartum year. A cluster-randomised controlled trial of the programme conducted between 2018 and 2021 found that children aged 2 years whose parents were in the intervention group and had received the programme had higher cognitive, language and motor development than those in the control group who had received the usual standard of care. The intervention was also found to be cost-effective and improve equity. The aim of this follow-up study is to examine the mid-term effects of the intervention and describe the views of caregivers, service providers and policymakers on the programme, the evidence of its impact and its translation into policies and practice. METHODS AND ANALYSIS: This is a follow-up study of participants in a cluster-randomised controlled trial to examine the mid-term effects of the intervention when children are 7 and 9 years old in Vietnam. We will re-enrol mother-child dyads from the original trial (622 women and their children in the intervention; 546 dyads in the control group). The primary outcome is children's intellectual ability. Secondary outcomes include children's emotional and behavioural development, quality of life, anthropometric indices, health conditions, health behaviour and education and parenting, maternal mental health, maternal quality of life, cardiovascular health and biomarkers of ageing together with women's and children's experiences of family violence.Outcomes will be measured using culturally and linguistically adapted standardised tools and study-specific structured questions. Differences in outcomes between trial groups will be assessed using mediation analyses and mixed-effects models, including a fixed effect for the trial group and adjusting for cluster effects as a random effect based on the intention-to-treat principle. An economic evaluation will estimate the cost-effectiveness of the intervention in improving child development at ages 7 and 9 years from healthcare and societal perspectives. A qualitative study will be conducted alongside the follow-up study using purposive sampling to describe the perspectives of caregivers, service providers and policymakers on the intervention, the evidence about its impact and its integration into national policies and services. ETHICS AND DISSEMINATION: Ethics approval was obtained from the Monash University Human Research Ethics Committee (2025-46034-125952). Study findings will be disseminated through multiple channels, including peer-reviewed publications, national and international conference presentations, seminars, policy briefings, lay language summaries to communes and media reports. TRIAL REGISTRATION NUMBER: ACTRN12625001113448.