Factors Associated With Severe Mental Illnesses Newly Diagnosed in Perinatal Psychiatric Care: Findings From a Large Clinical Cohort.

Background: The perinatal period represents a phase of increased psychiatric vulnerability, yet the factors linked to severe mental illnesses (SMIs) diagnosed during pregnancy or postpartum remain unclear. This study sought to identify associated and predictive factors of depression, bipolar disorder, and schizophrenia-related disorders diagnosed during pregnancy vs postpartum, with or without psychiatric comorbidity, in women seeking psychiatric care. Methods: Using a retrospective cohort design, data from 927 women who accessed specialized perinatal psychiatric services in Quebec City (Canada) were analyzed. Poisson regression models examined psychiatric, sociodemographic, medical, and obstetric correlates of perinatal SMIs. Results: Distinct profiles emerged according to diagnosis timing, disorder type, and comorbidity. During pregnancy, associated factors included being single, absence of prior psychotropic use, musculoskeletal conditions, and cluster C personality disorders. Past postpartum psychosis predicted bipolar disorder diagnosed during pregnancy. In the postpartum period, key correlates included history of anxiety or (hypo)manic symptoms, somatic-related disorder, suicidal behavior, absence of previous psychiatric diagnosis, and no new diagnosis during pregnancy. Foreign nativity and lack of psychotropic treatment were linked to depression across both periods. Conclusions: Results highlight period-specific and shared factors underlying perinatal SMIs. Their identification may improve early detection and targeted interventions for maternal mental health.