"The fetal response to noxious stimuli, described in detail in section 2, comprises two elements, both of which need to be present for the fetus to feel pain. The first of these involves nociception and a physiological stress response to it, while the second requires cortical processing of the nociceptive stimulus to produce a negative emotional perception. The evidence clearly suggests that the autonomic and endocrine pathways are in place for the fetus to mount a stress response as early as 18 weeks of gestation, with increases in cerebral blood flow, catecholamines and cortisol observed following invasive procedures. These responses can be attenuated by administration of fetal analgesia at the start of the procedure. It is worth noting that the fetal stress response can be elicited by a number of non-painful stimuli; the most extensively described is the response to acute hypoxia, where many of the components, such as increased cerebral blood flow, are part of a coordinated fetal response to minimise damage to organs such as the brain and heart. Increased cerebral blood flow, catecholamines and cortisol cannot therefore be interpreted as evidence that the fetus is feeling pain."