Professor Wadhwa introduces the concept of nutrition as an environmental signal about the availability of energy. Stress can be seen as a response that redistributes energy within the body owing to changes in the environment, to enhance the efficient use of that energy. Is there a role for stress during development? Nutrition and stress have a bidirectional relationship. It is clear that induction of stress alters choice of diet and energy use. Likewise, changes in nutrition may cause effects on foetal programming and development through manipulating stress pathways (e.g. cortisol and inflammatory cytokines), particularly in the periconceptual period.Professor Wadhwa asks if maternal stress can influence foetal development and long-term outcomes. The classic approach is to consider that “stress” correlates with maternal cortisol levels and this determines the length of gestation. However, a new longitudinal study is measuring “stress” in pregnant women through monitoring mental state, dietary input, heart rate, and other physiological parameters. This can pinpoint the levels of hormones and mental state of the mothers at precise times and any potential impacts can be correlated with the phenotype of the offspring. Available data suggest that pre-natal exposure to stress can indeed have long-term endocrine, immune, neurocognitive and epigenetic effects, including determining telomere length and stability.