Dr Derbyshire carried out a study for evidence of the existence of foetal pain and found that while the necessary biological system required for pain is complete at 26 weeks' gestation, real sensations of pain depend on experiences outside the womb.
The US government is now considering a law that would make it mandatory for doctors to tell women seeking an abortion that there is substantial evidence that the process of being killed in an abortion will cause the unborn child pain. Doctors who carry out abortions after 22 weeks without painkilling drugs would be fined $100,000 (Ģ57,700) and lose their medical licence.
Comparing the pain response of an unborn baby to that of a fruit fly larva that reacts to a flame by bending and rolling away, Dr Derbyshire described it as merely an automatic biological mechanism designed to avoid harmful stimuli. His notes in the British Medical Journal, said that, the neural circuitry for pain in foetuses is immature. He also said in his notes that pain becomes possible because of a psychological development that begins at birth when the baby is separated from the protected atmosphere of the womb and is stimulated into wakeful activity. He claims that pain is something that comes from experiences and develops due to stimulation and human interaction.
He said that, the proposals to inform women seeking abortions of the potential for pain in foetuses are not supported by evidence. Claiming that the legal or clinical mandates to intervene to prevent such pain are scientifically unsound and may expose women to inappropriate interventions, risks and distress. Dr Derbyshire described human pain as similar to an alarm system, with nerve endings in the skin activated by harmful stimuli like the triggers that set of alarms. He explained that the spinal cord is like the electrical wiring between a trigger and the alarm.
Scientists have previously suggested that the minimum level of anatomical development for pain is the completion of the ''spinothalamic'' muscular link from the spine to the thalamus, which is the part of the brain that processes information from the senses, at around 23-25 weeks.
A study published last week from University College London showed that scans on premature babies from 24 weeks having blood tests showed surges of blood and oxygen in sensory areas of their brains suggesting pain was being processed.
Anna Pringle, of the pro-life charity Life, said that it is known for certain that by the age of 20 weeks unborn children can respond to external aural stimuli such as music and conversation.