Intrauterine growth restriction (IUGR) means that the baby is smaller than its growth potential. Of course, all of the “norms” for what babies should weigh at which gestation have been made on Caucasian babies, so we need to be sensitive to that when we tell an Indian woman that her baby is “too small.”
Also, one should not confuse ‘size’ with ‘growth’. Sometimes a fetus is small but healthy and is growing ‘along its growth trajectory or centile’ while sometimes an apparently ‘normal’ sized fetus is actually IUGR because its potential is more than what is being achieved in utero.
So serial scans checking the growth of the baby are important.