Behavior not indicative of pain in stressed babies

November 30, 2017, University College London
Credit: CC0 Public Domain

In stressed newborn babies, behaviour alone is not a reliable way of assessing pain, according to new UCL and UCLH research.

The study, published today in Current Biology and funded by the Medical Research Council UK, found that hospitalised newborns, who are already stressed by their environment have a much larger pain response in their following a routine clinical skin lance than non-stressed babies. But this is not matched by an equivalent increase in their pain behaviour.

This disconnect between the behaviour of newborn babies under and their in response to pain has not been shown before and suggests that stress is an important factor in influencing how babies perceive and react to pain.

"We see that an increase in pain related brain activity in hospitalised babies is not always accompanied by an increase in typical pain behaviour, such as body movement and facial expressions. This leads us to question the use of behaviour alone as a way of assessing infant pain, especially in a stressful environment. In adults, stress can increase and our findings suggest that this is also true for babies," explained study lead, Dr Laura Jones (UCL Neuroscience, Physiology & Pharmacology).

"We know that repeated painful and stressful experiences in early life can negatively impact on the development of the central nervous system and our results suggest that controlling the of hospitalised infants may not only reduce their pain but also contribute to their healthy development."

Researchers simultaneously measured the behaviour and brain activity of 56 newborn babies before and after a clinically necessary heel prick in their first days of life, while also monitoring their stress.

In the babies with the lowest stress levels, brain activity and behaviour were associated with each other in that greater brain activity corresponded to a longer period of crying and/or grimacing. In the babies with the highest stress levels this association was broken: greater brain activity was not necessarily matched by a more marked behavioural response.

"These results are important for people who care for newborn babies. Behaviour such as crying or facial responses is widely used as a measurement of a baby's pain experience. Pain scores used for babies are based on these observations, because babies can't speak. While these methods are very useful, our findings suggest that they may not be appropriate for babies who are already stressed. We need to explore better ways to monitor pain, reduce stress and tailor our interventions accordingly," added co-author, Dr Judith Meek (University College London Hospitals NHS Foundation Trust).

The researchers measured the background level of stress in the babies using two approaches - heart rate variability and the level of cortisol in saliva. Each baby had a different level of stress due to natural variability in the population and their environments prior to the test.

During the test, brain wave patterns were tracked using electroencephalography (EEG) and behavioural changes, including facial expressions, and physiological changes were scored using a standard method called the premature infant pain profile (PIPP).

Two thirds of infants show a characteristic brain wave pattern for pain and a similar proportion display typical pain and a moderate pain score. The results show that the amplitude of the pain evoked brain waves was greater in with high stress compared to those with low stress.

"This work arose from a collaboration between scientists and clinical investigators. Our basic laboratory studies in the biology of pain processing in the developing nervous system have led to new discoveries about the formation of pain connections in the human infant brain. In the future, we plan to explore other environmental factors, such as maternal interactions, that may influence how our brains process at the beginning of our lives," added Professor Maria Fitzgerald, co-author and head of the UCL research group.

Explore further: Using EEG readings to detect pain in infants

More information: 'Nociceptive cortical activity is dissociated from nociceptive behavior in newborn human infants under stress' Current Biology (2017). DOI: 10.1016/j.cub.2017.10.063

Related Stories

Using EEG readings to detect pain in infants

May 4, 2017
(Medical Xpress)—A team of researchers affiliated with several institutions in the U.K. has conducted several trials that involved trying to detect pain in infants using EEG readings to measure brain response to painful ...

Continuous pain is often not assessed during neonatal intensive care

March 6, 2017
In an analysis of 243 neonatal intensive care units from 18 European countries, investigators found that only 2113 of 6648 (31.8%) newborns were assessed for prolonged, continuous pain. Daily assessments of continuous pain ...

Babies distinguish pain from touch at 35-37 weeks

September 8, 2011
Babies can distinguish painful stimuli as different from general touch from around 35-37 weeks gestation – just before an infant would normally be born – according to new research.

Babies' painkiller problem

August 19, 2016
You're in hospital and you need to have a blood test: What do you think would reduce your pain? Sucrose (sugar water)? Painkillers? You probably went with option 2. But in babies option 1 is often prescribed.

New method of infant pain assessment

December 21, 2011
Recently, the accuracy of current methods of pain assessment in babies have been called into question. New research from London-area hospitals and the University of Oxford measures brain activity in infants to better understand ...

Recommended for you

Breakthrough article on mechanistic features of microRNA targeting and activity

March 23, 2018
Giovanna Brancati and Helge Grosshans from the FMI have described target specialization of miRNAs of the let-7 family. They identified target site features that determine specificity, and revealed that specificity can be ...

Boosting enzyme may help improve blood flow, fitness in elderly

March 22, 2018
As people age, their blood-vessel density and blood flow decrease, which is why it's harder to maintain muscle mass after 40 and endurance in the later decades, even with exercise. This vascular decline is also one of the ...

Scientists pinpoint cause of vascular aging in mice

March 22, 2018
We are as old as our arteries, the adage goes, so could reversing the aging of blood vessels hold the key to restoring youthful vitality?

Sulfur amino acid restriction diet triggers new blood vessel formation in mice

March 22, 2018
Putting mice on a diet containing low amounts of the essential amino acid methionine triggered the formation of new blood vessels in skeletal muscle, according to a new study from Harvard T.H. Chan School of Public Health. ...

Gradual release of immunotherapy at site of tumor surgery prevents tumors from returning

March 21, 2018
A new study by Dana-Farber Cancer Institute scientists suggests it may be possible to prevent tumors from recurring and to eradicate metastatic growths by implanting a gel containing immunotherapy during surgical removal ...

Cold can activate body's 'good' fat at a cellular level, study finds

March 21, 2018
Lower temperatures can activate the body's 'good' fat formation at a cellular level, a new study led by academics at The University of Nottingham has found.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.