Sex-Based Differences in Core Symptoms of Autism Spectrum Disorder: A Systematic Review and Meta-analysis of Female Presentation

Introduction. Autism spectrum disorder (ASD) is more frequently diagnosed in males; however, evidence suggests that this disparity may partly reflect sex-related biases in diagnostic criteria and assessment tools. Aim. To characterize core ASD symptoms in females across the two DSM-5 diagnostic domains (Social Communication and Interaction, and Restricted and Repetitive Behaviors) and to quantify sex-based differences in symptom severity using standardized diagnostic instruments. Methodology. This systematic review and meta-analysis was conducted in accordance with PRISMA guidelines. We included studies published between January 2013 and September 2025 that reported on diagnostic processes or symptom presentation and were identified through searches of PubMed/MEDLINE, Scopus, and Web of Science. Results. Forty-eight studies were included in the qualitative narrative synthesis and seven in the meta-analyses, covering a total of 54,060 participants. Qualitative findings suggested inconsistent sex differences in social communication (DSM-5 Criterion A), whereas more domain-specific patterns emerged for restricted and repetitive behaviors (DSM-5 Criterion B), especially in sensory reactivity and restricted interests. Meta-analyses showed small but significant differences in overall ADOS-2 scores (d = −0.18; 95% CI [−0.35, −0.01]; p = 0.043) and the Social Affect domain (d = −0.23; 95% CI [−0.45, −0.02]; p = 0.033), with lower severity in females. No significant differences (d = −0.12; 95% CI [−0.39, 0.15]; p = 0.393) were found in the Restricted and Repetitive Behavior domain, but we observed high heterogeneity (I2 = 64.7%). Publication bias analyses suggested some funnel-plot asymmetry, although the overall interpretation of the findings remained unchanged. Conclusion. These results highlight the need for sex-informed diagnostic approaches that incorporate comprehensive clinical assessments to enhance early detection and reduce diagnostic delays in females with ASD.