Acute-care use rose faster for younger Ontario birthing parents

BACKGROUND: Limited data exist on substance use among parents, which can have major implications for parental and child health. We compared trends in substance-related emergency department care and hospital admission among birthing parents with dependent children and other females in Ontario, Canada, from 2008 to 2024. METHODS: In this population-based, repeated cross-sectional study, we used linked health administrative data from ICES. We compared changes in annual age-standardized rates of substance-related acute care in birthing parents with dependent children (children aged < 19 yr) to rates in a 1:1 age-matched comparator group of other females. We used joinpoint regression to examine average annual percent change (AAPC) between birthing parents and other females, overall and by age and substance type. RESULTS: The study included 5 025 622 eligible females across 2008 to 2024, of whom 46.9% were birthing parents. Between 2008 and 2024, substance-related emergency department visit and hospital admission rates increased more rapidly among the birthing parents than other females: emergency department visit rates increased from 387 to 894 versus 421 to 542 per 100 000 person-years, respectively (AAPC 4.8% v. 1.7%; p < 0.001), while hospital admissions increased from 99 to 259 versus 136 to 209 per 100 000 person-years, respectively (AAPC 6.0% v. 3.3%; p < 0.001). Rates increased more rapidly among birthing parents younger than 25 years than among other females younger than 25 years, but temporal trends were similar among birthing parents and other females aged 25 years and older. We observed growth in substance-related acute care across all substance types, but it was greatest for opioids, amphetamines, and cannabis. INTERPRETATION: Substance-related acute care use increased disproportionately among birthing parents with dependent children, particularly younger birthing parents and for opioids, amphetamines, and cannabis. Addressing these harms will likely require more inclusive, responsive, and integrated substance use services, as well as upstream policies that strengthen supports for parental and family health.