Sex Differences in Autistic Youth Born Extremely Preterm.

Purpose: To evaluate sex differences in autistic traits in youth born extremely preterm (EP; 23-27 weeks) who were later diagnosed with autism spectrum disorder (ASD) at 10-years.

Method: A longitudinal cohort design from the Extremely Low Gestational Age Newborn Study (ELGAN) followed N = 857 EP infants from birth through 10-years. EP infants later diagnosed with ASD (N = 61, 20 females) participated in the study. Group differences were evaluated via inferential and Bayesian statistics (values > 1 suggest evidence for alternate hypothesis) on ASD screeners (M-CHAT at 2-years, SCQ and SRS-2 at 10-years), and gold-standard diagnostic measures (ADOS-2, ADI-R) at 10-years.

Results: Males scored significantly higher than females on measures of Social Affect from the ADOS-2, t(34.27)=-2.20, BF = 2.33, and measures of Repetitive and Restricted Behaviors from the ADI-R, t(40.52)=-2.85, BF = 5.26. Bayesian estimates suggested marginal evidence for sex differences in Nonverbal Communication, t(30.66)=-1.81, BF = 1.25, and Verbal Communication, t(24.64)=-1.89, BF = 1.39, from the ADI-R, wherein males scored higher than females. No statistically significant sex differences were identified on any of the ASD screeners at 2 (M-CHAT) or 10 years (SCQ). No significant sex differences were observed on any subscales of the SRS at 10 years.

Conclusions: EP autistic males present with more autistic traits than EP autistic females on gold-standard diagnostic measures of autism at 10-years of age, despite not presenting with higher autistic traits on screeners at either age. These results align with sex differences observed in full-term, autistic youth. These results suggest ASD screeners may under identify autism in EP youth, particularly females.