Q. Can the fetus feel pain?
A. Yes by 8 weeks old the fetus can feel pain
by 8 weeks? Show me!
By this age the neuro-anatomic structures are present. What is needed is
(1) a sensory nerve to feel the pain and send a message to
(2) the thalamus, a part of the base of the brain, and
(3) motor nerves that send a message to that area.
These are present at 8 weeks. The pain impulse goes to the thalamus. It sends a signal down the motor nerves to pull away from the hurt.
Give me an example!
Try sticking an infant with a pin and you know what happens. She opens her mouth to cry and also pulls away.
Try sticking an 8 week old human fetus in the palm of his hand. He opens his mouth and pulls his hand away.
A more technical description would add that changes in heart rate and fetal movement also suggest that intrauterine manipulations are painful to the fetus.
Volman & pearson, "what the fetus feels," british med. Journal, jan. 26, 1980, pp. 233-234.
O.K., that is activity that can be observed, but is there other evidence of pain? After all, the fetal baby can’t tell us he hurts.
Pain can be detected when nociceptors (pain receptors) discharge electrical impulses to the spinal cord and brain. These fire impulses outward, telling the muscles and body to react. These can be measured. Mountcastle, medical physiology, st. Louis: c.V. Mosby, pp. 391-427 "lip tactile response may be evoked by the end of the 7th week. At 11 weeks, the face and all parts of the upper and lower extremities are sensitive to touch. By 13 1/2 to 14 weeks, the entire body surface, except for the back and the top of the head, are sensitive to pain."
s. Reinis & j. Goldman, the development of the brain c. Thomas pub., 1980