The 'gold standard' for optimal fetal growth and development

It is now becoming accepted that birth size per se is too crude an outcome measure to be used for the assessment of optimal intrauterine growth and development, and that a new vision of optimal fetal development is required for the 21st century. This will need to take account of both short- and long-term outcomes, to recognize that maternal body composition and diet can have long-term effects without necessarily affecting size at birth, and to take account of important interactions between the pre- and postnatal environments. At present, our understanding is limited and new definitions should only be considered as working hypotheses. Nonetheless, it is possible to begin to set out a framework for defining optimal fetal growth and development. This acknowledges the importance of developmental adaptations to alterations in the nutrient and hormonal milieu in utero and could have a major impact on human health in the century to come.