It has been suggested that in poor nutritional conditions, a pregnant female can modify the development of her unborn child such that it will be prepared for survival in an environment in which resources are likely to be short, resulting in a thrifty phenotype
(Hales & Barker, 1992). Individuals with a thrifty phenotype will have "a smaller body size, a lowered metabolic rate and a reduced level of behavioural activity… adaptations to an environment that is chronically short of food" (Bateson & Martin, 1999). Those with a thrifty phenotype who actually develop in an affluent environment may be more prone to metabolic disorders, such as obesity and type II diabetes, whereas those who have received a positive maternal forecast will be adapted to good conditions and therefore better able to cope with rich diets. This idea, which is also known as the Barker hypothesis
(Barker, 1992), is now widely (if not universally) accepted and is a source of grave concern for societies undergoing a transition from sparse to better nutrition (Robinson, 2001).