Teen motherhood is the prevalent childbearing pattern in most traditional populations. Yet early motherhood is associated with negative biological and social outcomes in the developed world. We review the teen pregnancy literature in light of this discrepancy, emphasizing two core debates. The first debate centers on whether teens have poor pregnancy outcomes compared to older women, and whether negative outcomes are biologically based. Second, we consider the debate over the confounding

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... of socio-economic conditions associated with being young. When teens are considered as a group, results are inconsistent across studies. When teens are disaggregated by age, the strongest finding across studies is that biological risk is concentrated in only the youngest of mothers. Negative consequences are associated with teen motherhood not because of chronological age per se, but because of relative developmental maturity and the availability of non-maternal support. In most traditional societies as well as in some sectors of developed societies, teen motherhood occurs within the context of extended kin networks and is subsidized through reliable economic and childcare assistance. Childrearing practices, rather than pregnancy per se, may explain much of the discrepancy in the prevalence, success and attitudes toward teen motherhood in traditional and developed societies. in non-human primates: An ecological and developmental perspective. In: Lancaster JB, Hamburg BA, editors. School-age pregnancy and parenthood. New York: Aldine de Gruyter, pp. 247-262. Apter D, Vihko R. 1983. Early menarche, a risk factor for breast cancer, indicates early onset of ovulatory cycles. J Clin Endocrinol Metab 57:82-86. Belsky J, Steinbery L, Draper P. 1991. Childhood experience, interpersonal development, and reproductive strategy: An evolutionary theory of socialization. Child Dev 62:647-670. Bentley GR. 1999. Aping our ancestors: Comparative aspects of reproductive ecology. Evol Anthropol 7:175-185. Bogaert AF. 2005. Age at puberty and father absence in a national probability sample. J Adolesc 28:541-546. Bogin B, Rios L. 2003. Rapid morphological change in living humans: Implications for modern human origins. Comp Biochem Physiol A 136:71-84. Bogin B, Wall M, MacVean RB. 1992. Longitudinal analysis of adolescent growth of Ladino and Mayan school children in Guatemala: Effects of environment and sex. Am J Phys Anthropol 89:447-457. Borgerhoff Mulder M. 1989. Early maturing Kipsigis women have higher reproductive success than late maturing women and cost more to marry. Behav Ecol Sociobiol 24:145-153. Boyce WT, Ellis BJ. 2005. Biological sensitivity to context: I. An evolutionary-developmental theory of the origins and functions of stress reactivity. Dev Psychopathol 17:271-301. M. 2007. Teenage pregnancy and adverse birth outcomes: A large population based retrospective cohort study. Int J Epidemiol 36:368-373. Chisholm JS. 1999. Death, hope and sex: Steps to an evolutionary ecology of mind and mortality. New York: Cambridge University Press. Chisholm JS, Quinlivan JA, Petersen RW, Coall DA. 2005. Early stress predicts age at menarche and first birth, adult attachment, and expected lifespan. Hum Nat 16:233-265. Coall DA, Chisholm JS. 2003. Evolutionary perspectives on pregnancy: maternal age at menarche and infant birth weight.