Currently, it is unknown, if fetal brain asymmetry can be altered in structural brain alterations such as callosal agenesis, genetic syndromes, or acquired disorders such as Fetal Alcohol Syndrome. Little is known about the consequences of inversely expressed asymmetry or marked symmetry of the perisylvian region. This retrospective study aimed to assess the frequency of normal and abnormal fetal brain asymmetry patterns in different fetal disorders.Analyzing fetal MR imaging data from 125 cases (37% CCA, 21% FASD, 42% genetic disorders) and 125 1:1 matched neurotypical control cases, asymmetry was visually assessed, focusing on side-differentiated STS expression and temporal lobe shape. Healthy controls exhibited a more developed right temporal lobe. Atypical asymmetry patterns were more prevalent in altered brain development cases (4% in controls vs. 33% in abnormalities overall). Fetuses with CCA (43%) and FASD (23%), trisomy-21 (48%) and Di-George syndromes (50%) showed atypical asymmetry patterns.Fetal brain asymmetry appears polygenic/multifactorial. Connectivity disorders (e.g., CCA), genetic backgrounds, and acquired conditions impact normal structural fetal brain asymmetry. These abnormalities, particularly in the perisylvian region, are detectable through fetal MRI. Atypical brain asymmetry is more common in states disrupting normal brain development, serving as a soft marker for neurodevelopmental disorders.Figure 1: An image of a fetus in GW 27+6 with trisomy 21 and symmetrically configured temporal lobes (STS depth left 3.1 cm (turquoise arrow) and 3.0 cm right (red arrow). On the right, the healthy control case in GW 28+0 with a typic asymmetry pattern.