Maternal Chronic Physical Conditions and Alcohol and Substance Use Disorders in the Preconception and Perinatal...

Background: Chronic physical conditions (CPC) and alcohol and substance use disorders (SUD) frequently co-occur, but this has not been examined perinatally. We explored the combined effects of CPC and prepregnancy SUD on perinatal SUD-related adverse events and outpatient care. Materials and methods: This population-based study comprised 77,474 people with and 664,751 without CPC with a birth in Ontario, Canada, 2013-2020. We measured the prevalence of prepregnancy SUD in both groups. We then calculated adjusted relative risks (aRR) of: (1) SUD-related adverse events (toxicity resulting in acute care use/death, or other SUD-related acute care use) and (2) outpatient care for SUD between conception and 365 days postpartum, comparing individuals with prepregnancy CPC and SUD (CPC + SUD), and those with CPC or SUD alone, to those with neither condition. Finally, adjusted relative excess risk due to interaction (aRERI) was calculated to quantify excess risk of the outcomes associated with CPC + SUD, wherein RERI > 0 indicated positive interaction. Results: aRRs of perinatal SUD-related adverse events were 26.79 (95% confidence interval [CI]: 23.12, 31.04) for people with CPC + SUD, 22.09 (95% CI: 19.59, 24.91) for SUD alone, and 2.01 (95% CI: 1.78, 2.27) for CPC alone-each relative to neither condition. There was evidence of positive interaction for CPC + SUD (aRERI: 3.69, 95% CI: 1.13, 6.46). Similar elevated aRRs were observed for perinatal outpatient care for SUD, but without a positive interaction for people with CPC + SUD. Conclusion: As people with both CPC and SUD have the highest risk of perinatal SUD-related adversity, they may need greater preconception and perinatal support.