Pregnancy is a complex period of human growth, development, and imprinting. Nutrition and metabolism play a crucial role for the health and well-being of both mother and fetus, as well as for the long-term health of the offspring. Nevertheless, several biological and physiological mechanisms related to nutritive requirements together with their transfer and utilization across the placenta are still poorly understood. In February 2009, the Child Health Foundation invited leading experts of this field to a workshop to critically review and discuss current knowledge, with the aim to highlight priorities for future research. This paper summarizes our main conclusions with regards to maternal preconceptional body mass index, gestational weight gain, placental and fetal requirements in relation to adverse pregnancy and long-term outcomes of the fetus (nutritional programming). We conclude that there is an urgent need to develop further human investigations aimed at better understanding of the basis of biochemical mechanisms and pathophysiological events related to maternal-fetal nutrition and offspring health. An improved knowledge would help to optimize nutritional recommendations for pregnancy.