Reporting physicians recruit eligible patients and report them immediately to their own National coordinators. This is done by filling in and transmitting the first sub-form of the Case Report Form. If no National coordinator is available, cases are directly reported to the Central Registry. Their task is also to assess each case every trimester of pregnancy and when the baby is 1 year old. This is carried out either by visit or phone interview and entails careful compilation of the corresponding sub-forms.
Physicians who cannot follow up their patients personally, can refer them to any clinical centre identified by their National coordinator.
Several Reporting physicians may refer to a single local centre. Each local centre receives an identification centre code from the National coordinator. Before starting to collaborate, centres need to obtain approval from the Ethics Committee of their institutions.