Postpartum diagnosis demonstrates a high risk for metastasis and merits an expanded definition of pregnancy-associated breast cancer.

Previous studies report conflicting data on outcomes of pregnancy-associated breast cancer (PABC). Our aim was to examine the effect of a postpartum diagnosis on maternal prognosis in a young women's breast cancer cohort. We conducted a retrospective cohort study of women age ≤45 years, diagnosed with breast cancer (n = 619) during 1981-2011 at the University of Colorado Hospital and The Shaw Cancer Center in Edwards, CO.