The frequency with which breast cancer is diagnosed in pregnant women is low (in the region of 1 in 1000 pregnancies), but the management of these women presents a considerable challenge to those involved in their care. Women frequently present with tumours displaying adverse pathological prognostic features. Initial investigation may be carried out as for non-pregnant women, but with particular attention paid to the risks of exposure to the foetus of ionizing radiation. Surgery can be carried out with seemingly little increased risk to the mother or foetus, but radiotherapy is usually avoided. In terms of short-term complications chemotherapy may be given relatively safely when administered outside of the first trimester and not around the time of delivery. However, the principle concern with all of these interventions is what the long-term implications for the newborn might be.