The ductus arteriosus (DA) is a large channel connecting the main pulmonary trunk with the descending aorta. In extremely preterm infants, the DA frequently fails to close and this results in a condition called patent ductus arteriosus (PDA). In these patients, PDA has been associated with increased mortality and morbidity in the neonatal period, and neonatal morbidities may in turn be associated with later deficits in cognitive functioning. PDA treatment with COX inhibitors, as ibuprofen or indomethacin, aiming at closing the PDA have been associated with numerous adverse effects and failed to demonstrate significant clinical benefits. Early treatment of PDA with paracetamol (acetaminophen ) has been proposed as an alternative to COX inhibitors. The ongoing pan-European TREOCAPA phase III study (NCT04459117) is a multicentre, double-blind, randomised, placebo-controlled superiority trial that assesses prophylactic use of paracetamol to improve survival without severe neonatal morbidity until discharge from hospital in infants of 23-28 weeks of gestational age. As long-term follow-up was not planned by the TREOCAPA protocol, TREOCAPA-LT study will use an existing European research infrastructure, the RECAP Preterm platform (https://recap-preterm.eu/), to follow-up the patients enrolled in the TREOCAPA trial using a parent-report questionnaire at 2 years of corrected age. The TREOCAPA-LT primary hypothesis is that there will be improved cognitive outcome at 2 years of corrected age in children born at less than 29 weeks of gestational age who were treated with paracetamol during the first 5 days of life in the TREOCAPA phase III trial.