There is substantial literature showing that birth weight is associated with differences in blood pressure within the reference range. These differences are found in children and adults, but they tend to be small. A 1-kg increase in birth weight is associated with &3 mmHg lowering in systolic pressure. This association is one of the associations with low birth weight that led to the “fetal origins hypothesis,” which proposes that the different forms of cardiovascular disease and type 2 diabetes originate through undernutrition during fetal life and infancy.1 Undernutrition at this time permanently changes the body’s structure and physiology. Like other living things humans are plastic during development, and their form and function is the product of the genes acquired at conception and of environmental influences, importantly nutrition, that regulate gene expression. Huxley et al2 recently reviewed 103 published studies on the association between birth weight and blood pressure. They concluded that the association was weaker in large studies than in small ones …