Evidence that autism often manifests differently between males and females is growing, particularly in terms of social interaction and communication, but it is unclear if there are sex differences in restricted and repetitive behaviours and interests (RRBIs) when rigorously focusing on the narrow construct level (i.e., stereotyped behaviour, restricted interests, insistence on sameness, and/or sensory experiences).
We conducted a systematic review and four random effects meta‐analyses investigating sex differences in narrow construct measures of RRBIs in autistic children, adolescents, and adults (Prospero registration ID: CRD42021254221). Study quality was appraised using the Newcastle‐Ottawa Quality Assessment Scale.
Forty‐six studies were narratively synthesised and 25 of these were included in four random effects meta‐analyses. Results found that autistic males had significantly higher levels of stereotyped behaviours (SMD = 0.21, 95% confidence interval (CI) [0.09, 0.33], p < .001) and restricted interests (SMD = 0.18, 95% CI [0.07, 0.29], p < .001) compared to autistic females. In contrast, there were no significant sex differences for sensory experiences (SMD = −0.09, 95% CI [−0.27, 0.09], p = .32) and insistence on sameness (SMD = 0.01, 95% CI [−0.03, 0.05], p = .68). The findings from the narrative synthesis were generally consistent with those from the meta‐analyses and also found qualitative sex differences in the way RRBIs manifest.