Diffusion measures of callosal fibers across three MRI time points. The reference cortical projection zone subregion (occipital) is depicted, which is representative of all subregions given that there were no diagnosis or sex interactions with subregion. (A) FA is higher in males than in females both ASD and TD groups. There were no differences in FA across ASD and TD. (B-D) MD, AD, and RD were all increased in females with ASD relative to TD females. Males with ASD did not differ from TD males.