Abstract Objective To characterize how autism spectrum disorder (ASD) risk varies with gestational age at birth. Study design We conducted a retrospective cohort study of children born between 2011 and 2023. ASD was identified using ICD-10 codes. Each ASD case ( n = 1861) was matched to ten controls using exact and propensity-score matching on sex, birth year, maternal age, ethnic sector, socioeconomic status, and region. Gestational age was grouped into clinically relevant categories, and associations with ASD were evaluated using Fisher’s exact test and conditional logistic regression. Results ASD risk increased progressively with prematurity. Compared with term birth (37–42 weeks), adjusted odds ratios (95% CI) were 1.37 (1.10–1.71) at 36 weeks, 1.67 (1.30–2.15) at 34–35 weeks, 2.14 (1.43–3.18) at 32–33 weeks, 2.95 (1.89–4.59) at 28–31 weeks, and 4.37 (2.26–8.44) below 28 weeks. Conclusion Earlier gestational age is associated with increased ASD risk in a dose–response manner.
Israel et al. (Tue,) studied this question.