Cancer in pregnancy is uncommon, with an incidence of about one to two cases in every 1000 pregnancies. There are no randomised trials on any aspect of the management of cancer in pregnancy. Stage for stage cancer outcomes are similar in women who are pregnant compared with those who are not. Misdiagnosis and delayed diagnosis are common where the index of suspicion by the mother and health carers is low. Surgical interventions pose some risk to the fetus, especially laparotomy for abdominal tumours and procedures undertaken during the first trimester. Chemotherapy is teratogenic in the early stages, but seems to be safe in later pregnancy, and radiotherapy can be used for localised tumours remote from the uterus, such as head and neck or limb neoplasms. Suspicious symptoms should be appropriately investigated during pregnancy, and recent advances in non-ionising-radiation staging techniques, such as MRI and ultrasound, are especially helpful. Surgical interventions can be safely undertaken with minimum risk, although there is almost always some element of maternal–fetal conflict.