Once the spinal reflex is developed at eight weeks, a foetus can feel pain.
A foetus develops the ability to feel pain very early in the pregnancy, potentially as early as seven or eight weeks. 
Important neurological developments occur in a foetus at around the 7-week mark, 18-week mark, and 26-week mark. Each one of these developments allows the foetus to feel pain. Therefore, a mother's access to abortion should be severely limited.  At around 7 weeks, the receptors in the skin begin to be developed. Then, around 18 weeks into the pregnancy, the receptors are connected to a spinal cord which carries the pain signals to the brain. Finally, between 23 and 26 weeks into the pregnancy, the spinal cord becomes connected to the cortex in the brain, the area where the pain signals are perceived. Each of these developments could allow the foetus to feel more pain. As the foetus can feel pain, an abortion procedure would be the same as torturing and murdering a child. Putting a foetus through the agony of a terminated pregnancy is inhumane and should not be permitted under any circumstance.
The British Royal College of Obstetricians and Gynaecologists begs to differ. They argue that for pain to be felt, the foetus must have developed the cortex. A foetus does not develop this part of the brain until it has been in the womb for 26 weeks, well past the time that most abortions occur. Therefore, any abortion before this time would be painless. The American College of Obstetricians agrees. Even if these medical institutions prove to be wrong, the fact that the foetus feels pain is not enough to warrant banning abortions. It is possible to administer anaesthesia to a foetus which would make the procedure humane.
[P1] A foetus can feel pain. [P2] Therefore, an abortion procedure inflicts unimaginable cruelty and suffering to the foetus. [P3] Therefore, the procedure should not be permitted.
[Rejecting P1] A foetus doesn't feel pain until very late in the pregnancy. [Rejecting P3] Even if it could, there are ways to make the procedure more humane.