Intrauterine growth restriction (IUGR) is a common and complex obstetric problem. IUGR is noted to affect approximately 10–15% of pregnant women. The study of the natural history of IUGR or fetal growth restriction (FGR) has particular challenges. Intrauterine growth restriction refers to a fetus with an EFW less than 10th percentile on ultrasound that, because of a pathologic process, has not attained its biologically determined growth potential. This chapter describes brief description of methods and indices for fetal assessment, classification, and stage-based classification and management of fetal growth restriction. Fetal well-being tests and indices could be classified as chronic or acute. The former becomes progressively abnormal due to increasing hypoxemia and/or hypoxia, the latter correlates with acute changes occurring in advanced stages of fetal compromise, characterized by severe hypoxia and metabolic acidosis, and usually precedes fetal death in a few days.