In This Article Expand or collapse the "in this article" section South African Birth to Twenty Project

  • Introduction
  • Introductory Texts
  • Bt20 Collaborations

Childhood Studies South African Birth to Twenty Project
Linda M. Richter, Julia de Kadt, Carren Ginsburg, Tawanda Makusha, Shane A Norris
  • LAST REVIEWED: 22 April 2013
  • LAST MODIFIED: 22 April 2013
  • DOI: 10.1093/obo/9780199791231-0064


The late 1980s in South Africa saw the Apartheid state falling apart and very rapid, unplanned urbanization occurring. Shanty towns mushroomed around formerly White cities and towns, portending profound effects on children’s health and development. In 1988 a group of researchers began a birth cohort study in Soweto-Johannesburg, with the aim of tracking urban children for ten years, not knowing at the time that these children would also be the first cohort born into a democratic South Africa. At the start, the study was called Birth to Ten (Bt10), but in 2000 it changed to Birth to Twenty (Bt20). The children came to be known colloquially as “Mandela’s Children” because they were born in the seven weeks following Nelson Mandela’s release from prison on 11 February 1990. A total of 3,273 singleton births were enrolled, beginning during the antenatal period with information also collected on pregnancy and birth. With a life-course approach, the study covers many of the major issues confronting the particular developmental phase of children and young people in which data is collected. In the early years, the emphasis was on environmental influences (poverty, migration, political violence), access to health services, nutrition and growth, childcare, and development. In the first few years of school, the emphasis was on cognitive ability, school performance, social adjustment, and inclusion. Later rounds of data collection explored early lifestyle risk factors: diet and weight gain, parental monitoring and supervision, educational failure, and sexual experimentation, and a wide range of physical (body composition and bone mineral density scans) and physiological measures (pubertal development, biochemical markers of insulin resistance) were introduced. Since their mid-teens, the study has focused on the prediction and measurement of risk, including: (i) sexual and reproductive behavior (sexual debut, unplanned pregnancy and sexually transmitted infections), (ii) early expression of the metabolic syndrome (obesity, hypertension, and insulin resistance) and (iii) social marginalization (school dropout, substance abuse, and conflict with the law). As, from October 2005, the next generation of children started to be born. While all the questionnaires used in Bt20 are being repeated with the third generation of children (called “3G” or “Birth to Twenty Plus—Bt20 Plus”), an in-depth study of pregnancy is also underway with a focus on foetal maturation, and growth and development in the first two years of life. In these first “1,000 days” foetal and early programming plays a critical role in setting the stage for later childhood and adult health and well-being. Since 2006, Bt20 has collaborated in several joint analyses, including in the 2007 Lancet “Child Development” series. The most significant of these collaborations is the Consortium of Health Oriented Research in Transitioning Societies (COHORTS), a network between the five largest and longest running birth cohort studies in low and middle income countries (LMICs): Pelotas (Brazil), Guatemala, New Delhi, South Africa and the Philippines

Introductory Texts

The Bt20 study is unique in that it is the largest and longest running study of child and adolescent health and development in Africa, as well as one of the few large-scale longitudinal studies in the world. This section provides an overview of the key papers outlining the study. Yach, et al. 1990 offers a rationale for the Bt10 study itself, while Yach, et al. 1991 highlights the environmental, political, and social context. The study methodology is outlined in Yach, et al. 1993 (cited under Parenting and Social Conditions), and the enrollment and sample characteristics are presented in Richter, et al. 1995. Ten years after the initiation of the study, the key findings and methodological challenges are reflected in Richter and De Wet 1999. The period of transition from Bt10 to Bt20 is documented in Richter, et al. 2004; and having almost reached the end of the twenty years of the study, a synopsis is provided in Richter, et al. 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.

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