When Do Babies Feel Pain? New Brain Research Sheds Light on a Longstanding Medical Mystery

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Discover the latest research on when babies begin to feel pain. Learn how brain development affects infant pain perception and why the question remains so complex.

When do we begin to feel pain?

It's a question that should be easy enough—and one that has baffled doctors, scientists, and philosophers for centuries. Some have claimed that fetuses at 12 weeks can feel pain, while others have theorized that even newborns are neurologically too simple to experience suffering.

Now, groundbreaking studies by University College London (UCL) at last may be able to determine when the sensation of pain begins. Using powerful brain imaging, scientists have tracked the development of pain-processing networks in the brain—the so-called "pain connectome." Their findings challenge conventional wisdom and offer new insights into when and how humans begin to experience pain.

Mapping the Pain Connectome: How Pain Perception Develops in the Womb

UCL researchers compared the brain activity of premature infants with adult pain-processing networks. What they found was a clear developmental pattern:

• Before 32 weeks since conception: Pain networks in the brain are immature.
• At 34–36 weeks: The sensory components of pain—how the brain can sense harmful stimuli—start functioning.
• 36–38 weeks: The emotional aspects of pain, which endow pain with its negative quality, become evident.
• Full-term birth (~40 weeks): The cognitive processing centers employed to evaluate and interpret pain continue to be immature.

This staged growth suggests that while babies are able to feel and respond to pain, what they perceive when they do is likely quite different from the experience of a little older children or adults. Basically, they may get the feeling that something's wrong but are not yet consciously interpreting that feeling as pain.

A History of Shifting Beliefs: Do Babies Actually Feel Pain?

The debate about infant pain is not new—it's been a work in progress for centuries:

• 18th and 19th centuries: Everybody believed that babies were highly sensitive to pain, even more so than adults.
• Late 19th century: As neuroscience advanced, this view was turned around. Scientists went on to disagree that because babies had underdeveloped nervous systems, they could not feel pain at all.
• 20th century: This peaked in a horrific period when surgery was routinely performed on babies without anesthetic—something that continued through the 1980s.
• 20th century to the present: We now have evidence from research that infants do respond to pain, both behaviorally and neurologically. Now, most are leaning towards acknowledging infant pain, although the subjective experience of it is still in question.

The Problem of Consciousness: Can We Ever Really Know?

The main issue is that pain is subjective. Unlike reflexes or heart rate, pain can't be measured directly. Researchers can observe behaviors (like crying or jumping back) and scan for brain activity, but these aren't necessarily signs that a baby is feeling pain like an adult.

For example:

• A baby withdrawing from a pinprick might be a reflex, not something they are consciously experiencing.
• Brain scans can detect activity related to pain, but perhaps that activity still exists without consciousness.

So while scientists get better at making educated guesses, the truth is, we might never completely know what a newborn experiences until we solve a much more complex mystery: How does brain activity give rise to consciousness?

Why This Research Matters

Understanding when and how pain sensation emerges isn't an abstract exercise in philosophy—it has real medical implications. It's a problem that has implications for the way we manage premature babies, for managing newborn pain, and for making moral decisions about fetal interventions.

Thanks to studies like UCL's, we are moving closer to kinder, wiser care. But debates over when pain begins are a reminder of how much we still have to learn about the human brain.

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