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.Lay AbstractMost autism research is focused on boys and men. We know less about autistic girls and women, including how many experience pregnancy and what their pregnancy-related needs are. We looked at how many first pregnancies occurred among autistic people, and how many people are diagnosed as autistic before, during and after pregnancy. We also looked at the demographic, social and health characteristics of autistic people before pregnancy, based on when they got their autism diagnosis. To do this, we studied all first pregnancies that happened in Ontario, Canada between 2004 and 2023. We identified autism diagnoses in health care records before, during and after individuals' pregnancies, up until 2024. We then described autistic and nonautistic people according to their age, neighbourhood-level income, rurality, immigration status, co-occurring conditions (like diabetes and depression), violence and health care access before their pregnancy. We found 1,148,470 first pregnancies in Ontario from 2004 to 2023; of these pregnancies, 1,086 (0.09%) were to autistic people. Among autistic people, 698 (64.3%) got their autism diagnosis before pregnancy, 36 (3.3%) during pregnancy and 352 (32.4%) after delivery. Compared with nonautistic people, autistic people were younger, more likely to live in low-income neighbourhoods and more likely to have lived in Canada long-term. They also had more co-occurring conditions; were more likely to experience violence; and used more health care services, including hospital services, before pregnancy. People who were diagnosed as autistic before pregnancy had even more co-occurring conditions, violence and health care use than people who were diagnosed as autistic after pregnancy. Our study shows that it is important to support the pre-pregnancy health of autistic people, including those who are waiting for a diagnosis. Our study also shows that health care providers need training to understand the needs of autistic girls and women.