Bt30 is set in the Gauteng province of South Africa. The study setting parameters comprised a population of approximately 3.5 million from the suburbs of Johannesburg-Soweto, as well as the suburbs of Diepkloof, Meadowlands, Dobsonville, extensions 1-7 of Lenasia, Eldorado Park, Coronation, Riverton and Klipspruit; covering about 200 square kilometres. The Bt30 sample consists of all single-birth children born within a 7-week enrolment window to mothers residing in Soweto-Johannesburg. Mothers were recruited at public clinics and must have remained in the area up until the child reached 6 months of age. The sample totalled 3,273 children, 50% with which the study is still in contact. Children and families are tracked throughout the Gauteng province.

Data has been collected across 23 points in the span of the study. Some rounds of data collection may include special interest variables but consistently collected data include demographic, socioeconomic and household information, community and school environments, health and nutrition, childcare, growth and physical activity, education and cognitive development, risk behaviours, and anthropometric and physiological measures

Several papers have detailed the methodology of the the cohort. Early papers offer a rationale for the Bt10 study and highlight the environmental, political, and social context. Papers published in 1993 and 1995 detail the enrollment and sample characteristics. Ten years after the initiation of the study, the key findings and methodological challenges are summarized in a 1999 publication. The period of transition from Bt10 to Bt20 is documented in 2004; and having almost reached the end of the twenty years of the study, a synopsis is provided in 2007 in which the study’s strengths and weaknesses are reviewed.

  • Richter, L. M., D. Yach, N. Cameron, R. D. Griesel, and T. De Wet. “Enrolment into Birth to Ten (BTT): Population and Sample Characteristics.” Paediatric and Perinatal Epidemiology 9 (1995): 109–120. DOI: 10.1111/j.1365-3016.1995.tb00124.x : The cohort included all children born within a seven-week period between April and June 1990 in the Johannesburg-Soweto area. The 3,273 enrolled cases, although roughly representative of the South African population, included a smaller proportion of better-off White children and their families because they tended to use private health services not accessible to the study.
  • Richter, L. M., and T. De Wet. “Growing Up in the New South Africa Birth to Ten: A Prospective Longitudinal Study from Birth to 10 Years of Age.” Special Section of the Newsletter of the International Society for the Study of Behavioral Development 36 (1999): 5–8. : Documents the background, rationale, and research focus of the Bt10 cohort study. It highlights some of the methodological challenges encountered during data collection and presents some key study findings describing households, maternal characteristics, and trends relating to early childcare.
  • Richter, L. M., S. A. Norris, and T. De Wet. “Transition from Birth to Ten to Birth to Twenty: The South African Cohort Reaches 13 Years of Age.” Paediatric and Perinatal Epidemiology 18 (2004): 290–301. DOI: 10.1111/j.1365-3016.2004.00572.x : The transition from B10 to Bt20 occurred when the study was extended for a further ten years of follow-up. The methodology is described with a focus on initial piloting, sample recruitment, and cohort maintenance. Study attrition is reported at an average of 3 percent per annum, with 70 percent of the cohort still in contact with the study by the end of its twelfth year.
  • Richter, L., S. Norris, J. Pettifor, D. Yach, and N. Cameron. “Cohort Profile: Mandela’s Children: The 1990 Birth to Twenty Study in South Africa.” International Journal of Epidemiology 36 (2007): 504–511. DOI: 10.1093/ije/dym016 : A synthesis of the Bt20 cohort study sixteen years after inception. It recounts the history of the study, the study’s core research themes, sample characteristics, attrition, and areas of data collection. A synopsis of the key study findings is provided and some of the strengths and weaknesses of the study are documented.
  • Yach, D., G. N. Padayachee, N. Cameron, L. A. Wagstaff, and L. Richter. “‘Birth to Ten’: A Study of Children of the 1990s Living in the Johannesburg-Soweto Area.” South African Medical Journal 77 (1990): 325–326. : This research brief provides a rationale for the Bt10 cohort study. In the context of rapid political and social change and high levels of urbanization, a study of children’s health and development is justified also by the impending demographic, nutrition, and health transitions taking place in South Africa.
  • Yach, D., N. Cameron, N. Padayachee, L. Wagstaff, L. Richter, and S. Fonn. “Birth to Ten: Child Health in South Africa in the 1990s. Rationale and Methods of a Birth Cohort Study.” Paediatric and Perinatal Epidemiology 5 (1991): 211–233. DOI: 10.1111/j.1365-3016.1991.tb00702.x : In order to highlight the context in which the cohort study was designed, factors describing the existing health status, services and infrastructure, as well as the political and social setting of the study location, are explored.