This UKRI-funded project partners with the Healthy Early Life Trajectories Initiative (HeLTI), a World Health Organisation-supported study that aims to test preconception interventions for the prevention of childhood obesity. HeLTI is a multi-country study with cohorts in Canada, India, China and South Africa; Trajectories works with the latter, hosted by the SAMRC Developmental Pathways for Health Unit at the University of the Witwatersrand in Johannesburg. The aims of this project are to investigate the social and ethical implications of public health interventions in the early life period from preconception to early childhood, and to develop innovative qualitative methodologies for studying the social factors that shape life trajectories. The successful candidates will work as part of a team, using mixed methods qualitative approaches, including interviews, ethnographic fieldwork and participatory methodologies to produce a fine-grained account of the lives of trial participants and to trace the interaction of biological and social factors that shape health outcomes from preconception to early childhood, and across the life course.The successful candidates will work closely with the Trajectories and HeLTI teams in a highly interdisciplinary research environment. Team members will be expected to travel to and spend significant time in Johannesburg, and to undertake regular trips for project meetings, writing retreats and workshops/conferences. The successful candidates will also be supported and expected to contribute to project-related activities, including event organisation, conference and workshop participation, presentation of findings, and writing publications.