The European Network of Teratology Information Services (ENTIS) is in a privileged position to perform independent post-marketing surveillance of drugs in pregnancy. The aim of this survey was to describe the legal requirements and procedures involved in obtaining ethical approval for collaborative cohort studies. We sent a survey questionnaire to all 28 Teratology Information Services (TIS), of which 25 (89%) in 18 countries completed our questionnaire. For 15 TIS, specific research ethical approval was mandatory. The review process was estimated to last from 2 up to 16 weeks. Procedures for patients' information and consent were oral (12), written (5) or both (3). Five TIS had no requirement to inform patients and seek consent. Since data on drug exposure during pregnancy are scarce, ENTIS research efforts should be further encouraged, and procedures optimized so that legitimate ethical and legal requirements do not translate into deterrent administrative constraints and costs.