The developing world is experiencing a rise in the prevalence of obesity, diabetes and cardiovascular disease to such an extent that it is often described as an epidemic. The most common explanation advanced for this phenomenon is the so-called epidemiological transition, with the biological basis of the thrifty genotype. The thrifty genotype theory suggests that genes derived from times of deprivation may result in adaptations that have adverse effects in times of plenty. However, a divergent theory is the so-called foetal origins of chronic disease, which ascribes the epidemic, in part, to an adverse intrauterine environment. There is compelling evidence, based on large numbers of epidemiological studies conducted in both developing and developed countries, that small size at birth in full-term pregnancies is linked with the subsequent development of the major features of the metabolic syndrome, namely glucose intolerance, increased blood pressure, dyslipidaemia and increased mortality from cardiovascular disease.