Postpartum mental illness during the COVID-19 pandemic: a population-based, repeated cross-sectional study.

<bold>Background: </bold>It is unclear whether the clinical burden of postpartum mental illness has increased during the COVID-19 pandemic. We sought to compare physician visit rates for postpartum mental illness in Ontario, Canada, during the pandemic with rates expected based on prepandemic patterns.<bold>Methods: </bold>In this population-based, repeated cross-sectional study using linked health administrative databases in Ontario, Canada, we used negative binomial regression to model expected visit rates per 1000 postpartum people for March-November 2020 based on prepandemic data (January 2016-February 2020). We compared observed visit rates to expected visit rates for each month of the pandemic period, generating absolute rate differences, incidence rate ratios (IRRs) and their 95% confidence intervals (CIs). The primary outcome was a visit to a primary care physician or a psychiatrist for any mental disorder. We stratified analyses by maternal sociodemographic characteristics.<bold>Results: </bold>In March 2020, the visit rate was 43.5/1000, with a rate difference of 3.11/1000 (95% CI 1.25-4.89) and an IRR of 1.08 (95% CI 1.03-1.13) compared with the expected rate. In April, the rate difference (10.9/1000, 95% CI 9.14-12.6) and IRR (1.30, 95% CI 1.24-1.36) were higher; this level was generally sustained through November 2020. From April-November, we observed elevated visit rates across provider types and for diagnoses of anxiety, depressive and alcohol or substance use disorders. Observed increases from expected visit rates were greater for people 0-90 days postpartum compared with 91-365 days postpartum; increases were small among people living in low-income neighbourhoods. Public health units in the northern areas of the province did not see sustained elevations in visit rates after July; southern health units had elevated rates through to November.<bold>Interpretation: </bold>Increased visits for mental health conditions among postpartum people during the first 9 months of the COVID-19 pandemic suggest an increased need for effective and accessible mental health care for this population as the pandemic progresses. [ABSTRACT FROM AUTHOR]