Choi M, et al. - Given that unique challenges are posed by pregnancy concurrent with, shortly before, or after breast cancer, due to the potential interaction between hormonal changes in pregnancy and breast cancer outcomes, researchers addressed this issue in this study including a cohort of female patients of reproductive age (n=3,687, <50 years) with breast cancer. They comprehensively captured exposure status and tumor features by linking a large institutional database and the nationwide claims database. Breast cancer during pregnancy, postpartum breast cancer (<12 months post-delivery), and pregnancy following breast cancer were included as exposures. Findings revealed a link of postpartum breast cancer, but not of breast cancer during pregnancy, with advanced stage, younger age at diagnosis (<35 years), hormone receptor-negative disease, and poorer survival. Overall survival was not compromised because of pregnancy after breast cancer.