From the day they are born, infants, including premature babies, can feel and express pain. In fact, premature babies are thought to have an increased sensitivity to pain as they have less ability to cope with pain. Newborn babies can respond to painful events such as a heel lance within the first minutes or hours of life.
Assessing pain in infants relies mostly on observing behaviours. Newborn infants are also capable of learning about pain. They may show behaviours early on to indicate that they have learned from previous painful experiences. By four to six months, babies who experienced continuing pain respond differently to pain.
Behaviour in response to pain
The best way to assess an infant’s pain is through changes in behaviour. Babies in pain tend to display pain in their facial expressions, arm and leg movements, and cries. They may try to guard or protect a sore part of their body or even pull on it. Changes in eating, moving, and sleeping can also be indicators of pain.
Facial expressions are generally regarded as the best single behavioural indicator of pain in all age groups. A grimace, eyes squeezed shut and mouth stretched open with a taut cupped tongue, is a common expression of pain.
Infants cry for reasons such as hunger, anger, or fear, but the cries of pain are distinctive. The typical pain cry is high-pitched, tense, harsh, non-melodious, sharp, short, and loud. However, the absence of crying does not mean a child is not in pain. An infant in severe pain may not cry at all, especially if they are premature or very young. They may simply not have the energy to cry.
An older infant in pain may pull at or guard a sore part of their body. They may also thrash about and kick, and may try to move away from the source of pain.
Despite these typical movements, premature and very young babies may not move and may become still. This absence of movement has also been noted in older children recovering from surgery. They recognize that moving hurts and so remain still to minimize the amount of pain.
Assessing an infant’s pain by observing takes skill and requires an understanding of infant development. This is why no single measure is used exclusively. Several measures are used to make a determination of pain.
Physical reactions to pain
Physiologic indicators, including heart rate, breathing rate, blood pressure, skin colour, vomiting, sweating, and dilated or widened pupils, are also used to determine if the infant is in pain. Because changes in these indicators can result from other causes, including stress, fear, or anxiety, they can be more difficult to interpret than behavioural changes. Despite these limitations, when used with behavioural indicators these signs can be useful as part of an overall assessment for a child in pain.