Introduction Repeated exposure to pain in preterm infants may lead to behavioural changes. Treatment of single painful procedures by non-pharmacological means has been well documented. Evidence of the efficacy in repeated painful procedures is marginal.

Methods Five routine heel sticks were evaluated within the first 14 days of life in nine preterm infants (<32 weeks of gestation). Oral sucrose was given before the procedure. Pain evaluation included videotaping, blinded assessment of the tapes by validated pain assessment tools and collection of salivary cortisol before and after the heelstick. The number of procedural interventions was documented.

Results The sample had a gestational age of 29 5/7 weeks (SD 1.4) and a birth weight of 1419 g (SD 328). 180.6 (SD 56) procedures were performed during the first 14 days of life. Interrater agreement was highest during heel stick 1–3 (α = 0.92–0.97) and decreased for heelstick 4–5 (α = 0.77–0.88), indicating a possible dampening of pain patterns. No significant difference in cortisol production before and after the heelstick was detected. A non-significant gradual decrease of cortisol levels took place over time.

Conclusion Measurements of salivary cortisol levels indicate that sucrose seems to be effective over time in pain control. The overall decrease of cortisol levels over time may be explained in association with downregulation of the hypothalamic–pituitary–adrenal axis. Diminished behavioural patterns in the first 14 days of life need further exploration.