The fetal over-nutrition hypothesis suggests that mothers who are overweight, gain weight rapidly during pregnancy, have high energy diets and those with on averagehigher glucose, insulin and lipid levels (even in the absence of diagnosed gestational diabetes or lipid abnormalities) programme their offspring to become overweight/obese and have vascular and metabolic problems later in life.If this hypothesis is correct then it would have major public health consequences since overweight/obese mothers would programme their offspring to be overweight/obese and have poor vascular and metabolic function; for their female offspring this would mean that they similarly went into their pregnancies overweight and with relatively high glucose and lipid levels, and would thus do the same with their offspring.Consequently, it is feared that if this hypothesis is true then interventions to reduce the obesity epidemic will fail to have any population impact for many generations.Despite this concern there is little high quality research that has attempted to test this hypothesis. Work in animal models demonstrate proof of principle,but may not be generalisable to humans. The small number of studies undertaken in humans have failed to use robust methods for demonstrating a specific intrauterine effect, as opposed to shared familial (environmental or genetic) effects, and have failed to adequately control for potential confounding factors.