The most universally followed and accepted definition is estimated fetal weight (EFW) less than 10th centile or abdominal circumference (AC) less than 10th centile for the period of gestation. In small for gestational age (SGA), it is important to differentiate between the constitutionally “healthy” SGA from pathologically growth restricted fetuses because perinatal morbidity and mortality differ vastly in these groups. Differentiate between healthy small for gestational age and fetal growth restriction, differentiate between early and late onset fetal growth restriction, role of umbilical artery Doppler, role of middle cerebral artery Doppler, role of ductus venosus Doppler, and stage-based protocol for management of SGA are discussed in this chapter.