This book explores the reasons for abnormal post-natal growth in preterm infants. It examines the long-term effects on developmental outcome as well as metabolic risks such as insulin resistance, type 2 diabetes, and hypertension. The contributors explore the risks and benefits of faster post-natal growth and catch-up growth in preterm infants. They describe tools for assessment of growth and early identification of faltering growth. They also explain methods for reducing growth faltering and for optimizing catch-up growth, including the new possibilities offered by customized fortification of human breast milk.