Background: Ultrasonography has recently become the principal means by which fetal well-being can be monitored and any deviation in fetal growth can be detected. Thus, the need for a gestational age independent parameter to assess fetal growth, has become a necessity. The trans-cerebellar diameter has been found to be nearly constant though-out gestation. Therefore, the present study was conducted with the aim to evaluate the diagnostic reliability and validity of the trans-cerebellar diameter to abdominal circumference ratio (TCD/AC) in assessment of normal fetal growth and derive population-specific transcerebellar diameter to abdominal circumference ratio (TCD/AC) for the Egyptian population.