Preterm and critically ill neonates experience many painful manipulations. The aim of the study is to evaluate the influence of these experiences and maternal deprivation on later pain behavior. Using Scoring systems, Prechtl general movements, skin conductance, testing flexor reflex levels with von Frey filaments and measuring salivary cortisol levels the investigators compare pain behavior of preterm (birth weight (BW) < 1500 grams), term neonates with need of ventilation (> 48 hours) with healthy neonates at the time of their first vaccination at the age of 3-4 months. The investigators are also testing flexor reflexes and skin conductance and general movements in regular intervals during the initial hospital stay. The investigators hypothesize that pain behavior is different at the age of 3-4 months in children with many early painful experiences.

Inclusion Criteria:

• Preterm < 1500 grams BW, critically ill term newborn on ventilation > 48 hours

Exclusion Criteria:

• Asphyxia
• ICH grade 3 and higher

Premature, critically ill term infants are recruited from the NICU of the University hospital of Cologne. Healthy newborns are recruited from the nursery of the University hospital of Cologne.