Establishing an accurate gestational age is the essential first step in diagnosis, ideally confirmed through an ultrasound scan performed early in the first trimester, since miscalculated dating is one of the most frequent reasons a fetus is wrongly labeled as growth restricted. Rather than depending on a single measurement, clinicians track growth over time through repeated ultrasound assessments of fetal biometry, generally spaced two to three weeks apart, to identify whether the fetus is following, falling away from, or plateauing on its expected growth curve. When estimated fetal weight drops below the tenth percentile and the growth trajectory shows a flattening pattern, this strengthens the case for a diagnosis of Fetal Growth Restriction rather than constitutional smallness. Doppler ultrasound plays a central role in evaluating fetal wellbeing, examining blood flow through the umbilical artery, the middle cerebral artery, and, when indicated, the ductus venosus, to determine how effectively oxygen and nutrients are reaching the fetus; the pattern of abnormality seen on these scans often directly informs how urgently delivery should be planned. Rounding out the surveillance approach, amniotic fluid volume is checked and fetal heart rate is monitored through non-stress tests and biophysical profile scoring. When the growth restriction appears alongside structural anomalies or raises suspicion of an underlying fetal or genetic condition, further genetic testing, such as chromosomal microarray analysis, may be advised to clarify the cause.