Australian Aboriginal Birth Cohort study: follow-up processes at 20 years

Progressive steps in a multiphase protocol were used for tracing, with modifications for the expected rural or urban location of the participants.Of the original 686 cohort participants recruited 68 were untraced and 27 were known to have died. Of the 591 available for examination 122 were not examined; 11 of these were refusals and the remainder were not seen for logistical reasons relating to inclement weather, mobility of participants and single participants living in very remote locations.The high retention rate of this follow-up 20 years after birth recruitment is a testament to the development of successful multiphase protocols aimed at overcoming the challenges of tracing a cohort over a widespread remote area and also to the perseverance of the study personnel. We also interpret the high retention rate as a reflection of the good will of the wider Aboriginal community towards this study and that researchers interactions with the community were positive. The continued follow-up of this life course study now seems feasible and there are plans to trace and reexamine the cohort at age 25 years.The hypothesis on developmental origins of health and disease which relates growth of intra-uterine and early life to the risk of chronic disease in adult life may be particularly relevant to the Aboriginal peoples of the Northern Territory (NT). Reports mainly from developed populations relate low birth weight (LBW) and fetal growth restriction (FGR) to the risk of cardiovascular disease, type 2 diabetes and hypertension in adult life, particularly if rapid catch-up growth has occurred [1]. Currently for NT Aboriginal people, LBW rates are double those of the non-Aboriginal NT population [2] and more LBW babies are surviving into adult life as infant mortality rates for Aboriginal people have markedly improved over the last decades [3,4]. At the same time the rates of the chronic non-communicable adult diseases of cardiovascular disease, hypertension, type 2 diabetes and