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The Fetus May Feel Pain from 20 Weeks

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; Washington Vol. XXV, Iss. 3,  (Jan 31, 2005): 35.

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PAIN IS A SUBJECTIVE EXPERIence. The fetus cannot tell us what it is feeling, and there is no objective method for the direct measurement of pain. To address the question of pain in the fetus, one must use indirect evidence from a variety of sources, and then make an informed guess. This approach is similar to that which we use with animals. We cannot ask animals how they feel, but infer from a variety of indirect approaches including study of their behavior, anatomy and physiology.

CONSCIOUSNESS

To feel pain or suffer discomfort, one needs to be conscious, to be aware. We do not know when, if at all, consciousness starts in the fetus. The biological basis of consciousness is little understood, although at least in adult humans, the evidence suggests that it is in some way associated with electrical activity in the cerebral cortex. Susan Greenfield has explained that one should not think of consciousness as an all-or-none phenomenon but rather that it may come on like a dimmer switch. This concept of evolving consciousness could apply to the developing fetus, in whom experience is most unlikely to be similar to an adult's. Furthermore, the fetus may not have the same physical basis for conscious experience as the older human.

ANATOMY

The most important evidence for fetal pain is anatomical. For the fetus to feel pain, it is necessary for stimuli to travel around the body (nociception). This involves neural connections between peripheral receptors and the spinal cord, upward transmission via the spinal cord to the thalamus, and from there to the outer cerebral layers. The development of the human nervous system is a progressive and ascending process, with the cerebral cortex the last region to develop.

Connections from the periphery to the spinal cord are formed early, at about eight...