Shaheen JD, Hershkovitz R, Mastrolia SA, et al. - Two fetal weight estimation formulas generated by Hadlock, a formula that includes head circumference parameter (H1), and another (H2) which excludes this parameter were assessed for their equivalence. In addition, researchers sought the patients in which H2 formula is less reliable to use. In this retrospective cohort study, a total of 1,220 sonographic fetal weight estimations performed within 7 days of delivery and recorded at a single medical center from January 2014 to December 2016 were included. The mean birth weight of 3,288.92 ± 641.27gr was reported. the analysis suggests higher accuracy of H1 formula than H2 formula in predicting fetal weight at term. However, only a small accuracy difference was found. Therefore, in case the technical difficulty in ultrasonographic evaluation of HC is encountered, the Hadlock formula that excludes head circumference can be used with confidence. They recommend practicing caution with higher values of femur length and lower maternal age.