Supplemental Material for: Obstacles to overcome when performing pan-European multicentre studies in extremely preterm infants: results of a survey among researchers of the Pulmonary Research Consortium of ESPR

Between June and September 2025, we sent out a questionnaire on care structures and management of EPI and ethical requirements for conducting an observational study to the previously identified national representatives of all 24 European countries within the European Society for Paediatric Research Pulmonary Research Consortium. </p><p dir="ltr">Results: Our survey found wide variations in care structures across European countries which were reflected by different inter-hospital transfer strategies before discharge, differences in data accessibility and follow-up data availability.

We observed varying use of outcome definitions, discrepancies in their execution and availability of underlying physiological measures limiting the reliability on retrospective data. Differences in ethical requirements present further issues for successfully performing multicentre studies in Europe.</p><p dir="ltr">Conclusion: These results highlight the obstacles researchers are faced with when planning multicentre studies involving EPI across Europe.</p>