Teenage pregnancy is associated with poor maternal and child health outcomes that can resonate throughout individuals' lives and into future generations. Across many industrialised nations, teenage pregnancy rates remain high despite extensive efforts to introduce government policy and public health interventions aimed at reducing rates of young motherhood. Indeed, more than 1.25 million teenagers become pregnant in OECD nations each year (UNICEF, 2001). In this chapter, we use a branch of evolutionary theory (life-history theory) that studies life cycles within an environmental context to better understand what are likely to be the persistent underlying antecedents of teenage pregnancy.

The main issues

Policy efforts to reduce the rates of teenage pregnancy have had little impact (e.g. Johns et al., 2011); this chapter aims to use evolutionary theory as a practical guide to identify antecedents of early reproduction. Life-history theory is devoted to the study of survival, growth and development and reproduction (i.e. life cycles) in an ecological context. It focuses on the timing and duration of major events such as age at first reproduction, number and size of offspring, interbirth intervals, length of parental investment (e.g. age at weaning), and lifespan. These life-history traits often covary in what is referred to as a reproductive strategy. This theoretical framework has been applied successfully to the study of non-human animals' life cycles (see Stearns, 1992) and the timing and duration of life histories, including reproductive timing, in traditional human populations (e.g. Hill and Hurtado, 1996).