Pain in the neonate and fetus

The effects of early pain experience in neonates on pain responses in infancy and childhood

Iatrogenic pain is commonplace in newborn infants yet we know very little about its long-term effects. This article reviews the evidence for and against the suggestion that painful procedures experienced in the perinatal period influence subsequent pain responses in infancy or in childhood. The evidence suggests that early experiences with pain are associated with altered pain responses later in infancy. The direction of the altered response depends, in part, on the infant's developmental stage (full-term vs preterm), and his or her cumulative experience with pain. Preterm infants that are hospitalized as neonates and subjected to painful procedures appear to have a dampened response to painful procedures later in infancy. Full-term neonates exposed to extreme stress during delivery, or to a surgical procedure, react to later noxious procedures with heightened behavioral responsiveness. Studies in which analgesic agents (local anesthetics or opioids) have been administered prior to noxious procedures demonstrate less procedural pain and a reduction in the magnitude of long-term changes in pain behaviors. The precise determinants of these changes, their extent, and their permanence are not known but they appear to involve noxious stimulus-induced peripheral and central sensitization, as well as classical conditioning.

Pain in the very preterm baby: 'suffer little children?'

Increases in medical expertise and technological advances have enabled the survival of very preterm babies who form a new and growing population. Comparisons between the foetus, full-term baby and the very preterm baby indicate that by the time the foetus is of 23 weeks gestation, many of the abilities, for example, sensing touch, hearing, seeing, moving and even learning may be common to all three. Thus, the very preterm infant who has been described as a unique organism, is not passive, but is a sentient being who is unlikely to survive without the medical and technical support of the Neonatal Intensive Care Unit (NICU) where he/she is exposed to frequent and regular medical procedures. Many of these procedures would be, for any normal, fully developed human being at best uncomfortable and at worst painful. Reviews within the past 10 years have shown that the neurochemical, anatomic and functional systems of newborns are developed enough to perceive pain. More importantly, rat pup studies have indicated that not only may the very preterm baby experience pain but it may experience it more intensely than the more mature infant. Moreover, there may be serious consequences of repeated painful medical intervention. Alleviation of pain and/or distress in very preterm infants is, therefore, an important issue.

The undertreatment of pain in children: an overview

At the present time, the management of pain in children is not addressed with the same vigor and enthusiasm as is the management of pain in adults. Limited accessible information and limited research have allowed inaccurate and inadequate information to persist, which serves to justify the status quo. The personal nature of pain and the complexity of assessing it have offered further obstacles. Changes are occurring, however, which will dramatically alter present practice. It will soon be unacceptable socially and medically to ignore the suffering of children.

Developmental and psychological factors in children's pain

It is clear that previously we were ill-informed and misinformed about children's pain. Recent investigations have led not only to a burgeoning of understanding of pediatric pain, but also an increase in our ability to appropriately measure and treat children's pain. Both pharmaceutical and nonpharmaceutical treatments have made major strides in the past few years. Even more crucial is the change that has happened in the willingness of health professionals to recognize that children do suffer pain and that aggressive treatment is often indicated. However, careful consideration must be given to physiologic, cognitive, affective, and psychosocial development, both in order to maximize the effectiveness of interventions and to recognize the limits that development may place on any specific approach.