The primary purpose of this article is to identify factors that are associated with worsening mood and anxiety trajectories across the perinatal period among pregnant individuals receiving treatment with a selective‐serotonin reupdate inhibitor. This secondary analysis of primary data from the original article, Trajectories of Depressive and Anxiety Symptoms Across Pregnancy and Postpartum in Selective Serotonin Reuptake Inhibitor‐Treated Women, explores if number of lifetime episodes of depression as characterized in the Mini‐International Neuropsychiatric Interview, elevated maternal adverse childhood experiences (ACE) score, or specific obstetric or neonatal factors from the Peripartum Events Scale (PES) were associated with membership in trajectory groups with the highest symptom burden. No difference in ACE scores or obstetric or neonatal factors were associated with membership in the trajectory groups using Wilcoxon rank sum tests and bi‐variable logistic regression. The trajectory group with the highest anxiety symptom burden experienced more lifetime episodes of depression compared to other groups (odds ratio = 1.17, 95% confidence intervals, 1.02–1.34, p= 0.03). Congruent with other studies, we found a high prevalence of co‐occurring mood and anxiety symptoms and that past episodes of depression remain an important historical risk factor for perinatal symptom burden. This reinforces that past experiences of depression increase not only the risk of future symptoms but also higher symptom burden during antidepressant treatment. Past episodes of depression are associated with higher symptom burden of anxiety and depression in selective‐serotonin reupdate inhibitor (SSRI)‐treated perinatal patients.There is a high correlation between anxiety and depressive symptoms in perinatal patients.No positive correlation was found between scores on the Adverse Childhood Experience and symptoms of anxiety and depression in perinatal patients treated with SSRIs. Past episodes of depression are associated with higher symptom burden of anxiety and depression in selective‐serotonin reupdate inhibitor (SSRI)‐treated perinatal patients. There is a high correlation between anxiety and depressive symptoms in perinatal patients. No positive correlation was found between scores on the Adverse Childhood Experience and symptoms of anxiety and depression in perinatal patients treated with SSRIs.