Autism diagnoses before and after pregnancy: a retrospective population-based cohort study in Ontario, Canada

Few studies have examined the reproductive health of autistic girls and women. We undertook a descriptive retrospective population-based cohort study in Ontario, Canada, 2004 to 2023. Among first pregnancies, we (a) estimated the proportion occurring in autistic individuals, (b) examined the distribution of autism diagnoses before, during and after pregnancy and (c) described the preconception characteristics of childbearing autistic individuals based on timing of diagnosis. Autism was identified using a validated algorithm before, during and after pregnancy, the latter until 2024. Preconception socio-demographic and clinical characteristics were compared in each autism diagnosis timing group with nonautistic individuals using descriptive statistics. There were 1,148,470 first pregnancies, of which 1,086 (0.09%) were to autistic individuals. Among autistic individuals, 64.3% had their first diagnosis recorded before conception, 3.3% during pregnancy and 32.4% after delivery. Compared with nonautistic individuals, autistic individuals, regardless of the timing of diagnosis, were younger and more likely to live in low-income neighbourhoods, be long-term Canadian residents and experience co-occurring conditions, violence and high health care use preconception, with the highest rates of these factors among those with pre-pregnancy autism diagnoses. Findings show the importance of addressing preconception health needs of autistic individuals, including those awaiting a diagnosis, and autism training for health care providers.