Why do we need sex-balanced studies of autism?

Males are diagnosed with autism much more frequently than females, and most research study samples reflect this male predominance. The result is that autistic females are understudied. There is a critical need to increase our understanding of autistic females, both biologically and clinically. The only way to do this is to recruit sex-balanced cohorts in studies so that similarities and differences between males and females can be evaluated in all autism research studies. The purpose of this commentary is to (1) provide historical context about how females came to be under-represented in all research, not just in the field of autism and (2) learn from other areas of health and medicine about the potentially dire consequences of not studying both sexes, and (3) draw attention to the need to recruit sex-balanced cohorts in autism research, particularly in neuroimaging studies.