Almost 40% of postpartum psychiatric hospital admissions are brief, lasting 72h or less. We aimed to identify unique subgroups of women within this group to inform better intervention. All women in Ontario, Canada with a brief postpartum psychiatric admission (≤ 72h) (2007-2012)(N = 631) were studied using latent class analysis. We identified distinct subtypes of women and compared women within each subtype on post-discharge mental health indicators: physician visits, emergency department (ED) visits and readmissions. We identified four clinically distinct classes: (1)women with no diagnosed mental illness (2 years before delivery) (n = 179; 28.4% of the sample); (2)women with pre-existing history of severe mental illness (i.e. psychosis) (n = 161; 25.5%); (3)women with pre-existing history of non-psychotic mental illness (n = 211; 33.4%); and (4)adolescent rural-dwelling women with alcohol and substance use disorders (n = 80; 12.7%). In the 1 year post-discharge, women in classes 1-3 were more likely to have post-discharge physician visit than women in class 4 (p < 0.05) and were less likely to have a psychiatric ED visit (p < 0.05). Women in class 2 were most likely to be readmitted (p < 0.05). We identified clinically distinct subgroups of women with brief postpartum psychiatric admissions who may each benefit from differing targeted preventive strategies and post-discharge treatment planning.