Rationale: Propofol, a rapidly acting anaesthetic agent, is currently used unlicensed in the clinical care of (preterm) neonates as sedative for endotracheal intubation. Neonates receive the same propofol doses per kg bodyweight, independent of their developmental stage (gestational age, postnatal age), morbidity, co-medication, etc. This is related to a high failure rate of intubation attempts and leads to hypotension in around 40 percent of patients. Propofol research in newborn infants is on the recently published priority drug research list of the European Medicines Agency (EMA). Propofol metabolism and elimination (PK: pharmacokinetics) as well as propofol effects (PD: pharmacodynamics) highly depend on the stage of development and on the genetic make-up of a patient. This study is based on the hypotheses that currently used single doses of propofol for newborn infants can be optimized and that this will improve the quality of sedation and increase the safety of the patients.