This study investigated the clinicopathologic characteristics and survival of women diagnosed with pregnancy-associated breast cancer (PABC) in Taiwan. PABC is defined as breast cancer diagnosed during pregnancy or within 1 year after obstetric delivery. Our sample of PABC patients (N = 26) included all patients diagnosed at a major medical center in northern Taiwan from 1984 through 2009. Among these patients, 15 were diagnosed during pregnancy and 11 were diagnosed within 1 year after delivery. The comparison group included 104 patients within the same age range as the PABC patients and diagnosed with breast cancer not associated with pregnancy from 2004 through 2009 at the same hospital. Patients' initiating treatment delayed, 5-year and 10-year overall survival were delineated by stratified Kaplan-Meier estimates. Patients' characteristics were associated with initiating treatment delayed was evaluated with multivariate proportional hazards modeling. Antepartum PABC patients were younger and had longer time between diagnosis and treatment initiation than postpartum PABC patients. The predictor of treatment delayed was including birth parity, cancer stage, and pregnancy. The PABC group had larger tumors, more advanced cancer stage, and tumors with less progesterone receptor than the comparison group. The antepartum PABC patients had higher mortality than postpartum PABC and comparison groups within 5 years after diagnosis. Based on these results, we confirmed that pregnant women with breast cancer were more likely to delay treatment. Therefore, we recommend that breast cancer screening should be integrated into the prenatal and postnatal routine visits for early detection of the women's breast problems.