This study aims to establish the z score reference ranges of fetal head circumference and other measurement of fetal measurements including biparietal diameter, fronto-occipital diameter, length of the corpus callosum, lateral ventricle, transverse cerebellar diameter, height of the vermis, anteroposterior diameter of the vermis，height and width of normal fetuses from 18 to 40 weeks' gestation.
Method-A cohort-based study was conducted on low-risk singleton pregnancies with healthy fetuses. The measurement was performed using simple 2-dimensional MRI on the typical fetal standard view. The reference ranges were constructed according to gestational age (GA), biparietal diameter (BPD), as independent variables based on the best-fit models, both mean and standard deviation (SD).