Breast cancer during pregnancy is relatively uncommon. However, the incidence is expected to increase as more women delay childbearing. A challenging situation emerges for all persons involved ‑ patient, family and medical care workers ‑ since two lives are at risk with contradicting priorities. Breast cancer treatment is possible during pregnancy. The treatment plan needs to adhere as closely as possible to standardised protocols for nonpregnant patients, with some considerations to minimize fetal exposure and risks. This concerns mainly limiting radiation exposure and timing of chemotherapy to start in the second trimester. The prognosis of pregnant women does not seem to differ from that of nonpregnant patients when matched for age and stage of the disease. This literature review concentrates on the diagnosis, treatment and outcome of patients diagnosed with breast cancer during pregnancy.