Newborn Babies’ Brains May Not Be Wired For Adult-Like Pain Until Weeks After Birth

LONDON — New research reveals that the neural networks responsible for processing pain develop in stages during the final weeks of pregnancy and early life, suggesting that premature babies and even full-term newborns experience pain very differently than adults do.

Using brain scans from 372 infants and 98 adults, British researchers found that the brain circuits needed for the sensory, emotional, and cognitive aspects of pain mature at different rates. Even babies born at full term haven’t developed the complete adult-like pain processing system by the time they’re born.

The findings could alter how doctors treat pain in premature babies, who often undergo dozens of painful medical procedures during their hospital stays.

“Newborn neural pathways required for mature pain processing in the brain are incomplete in newborns compared with adults, particularly regarding the emotional and evaluative aspects of pain,” the researchers wrote in their study published in the journal PAIN.

Pain Networks Develop in Stages

Scientists have long known that pain isn’t exclusively about feeling hurt. When adults experience pain, three main brain networks activate: the sensory network (which identifies where and how intense the pain is), the emotional network (which makes pain feel unpleasant and threatening), and the cognitive network (which helps us understand, evaluate, and control our response to pain).

Researchers from University College London and King’s College London used functional magnetic resonance imaging (fMRI) to examine how these networks develop. They analyzed brain scans from infants ranging from 26 to 42 weeks of gestational age – essentially from very premature babies to full-term newborns.

The team focused on 12 brain regions known to be involved in pain processing, including areas like the thalamus (the brain’s relay station), the somatosensory cortex (which processes touch and pain sensations), and the prefrontal cortex (involved in thinking and decision-making).

Rather than a uniform development pattern, researchers discovered a clear hierarchy in how these networks mature.

The sensory pain network – responsible for detecting and locating pain – develops first and reaches adult-like strength between 34 and 36 weeks of pregnancy. From an evolutionary perspective, babies need to be able to detect harmful stimuli to survive.

The emotional pain network, which includes brain regions that make pain feel threatening and unpleasant, reaches adult levels later, between 36 and 38 weeks of pregnancy. These areas include the anterior cingulate cortex and anterior insula.

Most striking was the cognitive network, centered in the prefrontal cortex. These brain areas help us understand and control our response to pain, but they remain significantly underdeveloped even in full-term babies. Some connections within this network weren’t even detectable until 36 weeks of pregnancy.

Premature Babies and Pain Processing

Babies born before 32 weeks showed dramatically weaker pain networks overall compared to adults. These extremely premature infants often require intensive medical care involving numerous painful procedures like blood draws, breathing tube insertions, and surgeries.

Early medical interventions occur when pain processing networks are at their most vulnerable and underdeveloped. While these babies can feel pain, their brains may not process it in the same way as more mature infants or adults.

Interestingly, the study also found that some pain connections in premature babies were actually stronger than in adults – a phenomenon called “hyperconnectivity.” In the sensory network, 70% of connections were significantly stronger in late-term infants compared to adults. This hyperconnectivity might explain why premature babies sometimes seem to have exaggerated responses to painful stimuli.

The rapid changes in pain processing during this developmental period mean that “pain processing, and consequently pain experience, changes rapidly over this developmental period and unlikely to be the same as in adults, even at term.”

The Future of Infant Pain Management

Currently, pain assessment and treatment in infants often relies on behavioral cues like crying or facial expressions, but this research shows the underlying neural experience may be quite different from what doctors assume.

Rather than treating newborns as simply smaller versions of adults, healthcare providers may need specialized, age-appropriate pain management strategies. For parents of premature babies and healthcare providers caring for them, this research offers both concerning insights and hope for better pain management strategies.

Most importantly, it demonstrates that premature babies require specialized medical care that accounts for their developing nervous systems.

“Our results suggest that preterm babies may be particularly vulnerable to painful medical procedures during critical stages of brain development,” says lead author Lorenzo Fabrizi, a University College London professor of Neuroscience, Physiology & Pharmacology, in a statement. “The findings therefore emphasize the importance of informed paediatric care, including the role of tailored pain management and carefully planned timing of medical interventions for newborns, particularly those born preterm.”