Cancer during pregnancy is relatively rare, but its incidence has been increasing over recent years. A European study has been launched in 2005 by F. Amant (KUL) to register all pregnant patients with a cancer diagnosis with or without treatment during pregnancy (surgery, chemotherapy and/or radiotherapy). All infants exposed to chemotherapy and/or radiotherapy are also followed up by pediatricians, neurologists, cardiologists and psychologists. In Belgium, French- and Dutch- language hospitals are working in close collaboration to follow these pregnant patients. The national results are summarized in this paper.