MRI study of the human fetal brain is a complicated, important and difficult scientific problem, which has an application inclinical practice. Meanwhile, the boundaries of individual geometric characteristics of fetal brain structures are still blurred andrequire a clarification. A sample of 105 participants with healthy fetal brain, is considered. It is shown that the relationshipbetween the growth of individual brain structures sizes (cerebral fronto-occipital diameter, cerebral biparietal diameter, corpuscallosum length, transverse cerebellum diameter, vermis height) differs depending on the trimester. The advantage of lineardependence for the growth of brain structures for each of the considered trimesters was demonstrated versus power-lawregression. The resulting growth models for each trimester will make it possible to more accurately determine whether a casecorresponds to the norm using a combination of several linear dimensions at once.