Introduction: Neonatal experience of pain and distress can lead to developmental problems, which can be associated with long-term emotional and behavioural disorders. The aim of the study was to analyse the effects of early experiences of pain and maternal reactions on the pain and coping behaviour of preterm infants.
Methods: In a prospective longitudinal study of 69 very low birth weight (VLBW) preterm infants, neonatal data regarding painful manipulations, analgesics and sedatives, and general medical condition (Nursery Neurobiological Risk Score; NBRS) were assessed. At the (corrected) age of 36 months, 53 preterm infants and a control group of 23 full-term infants were re-examined. Pain and coping behaviour were estimated by a questionnaire. Maternal anxiety was assessed in semi-structured interviews at the age of 3, 12 and 36 months in the preterm group.
Results: The mean gestational age was 29 + 0 weeks (23 + 3 to 34 + 1), the mean birth weight 1058 g (380 to 1480 g) in preterms and 39 + 3 weeks (37 + 0 to 42 + 0) and 3379 g (2400 to 4130 g), respectively, for the full-terms. The sex ratio was equal, 45.3 % of the preterms were multiples (controls 34.8 %). Preterms had higher descriptive scores for all types of pain situations. After controlling for other associated factors, a negative correlation between birth weight and later pain behaviour in medical situations remained. Preterms had a more negative coping behaviour during every day injuries. In terms of coping behaviour, only a shorter inpatient treatment in the neonatal period was associated with social withdrawal after controlling for other associated factors. Maternal anxiety at the age of 12 and 36 months was associated with negative coping behaviour following simple injuries.
Conclusions: While preterms do not have a higher pain threshold in general, a subgroup does have a higher risk for later sensation to pain. Preterms use more unfavourable coping strategies in simple injuries which, in turn, seem to be decisively mediated by maternal anxiety. Future research should focus on psycho-social factors involved in the development of pain reactions, as these can predispose towards behavioural disorders.