"Fetal behavioural responses have also been used as indicators of stress or pain. Shortly after the development of skin sensitivity, around 10 weeks, repeated stimulation results in hyperexcitability and a generalised movement of all limbs. After 26 weeks, this generalized movement gradually gives way to more coordinated behavioural responses that indicate improved organisation within the nervous system. Infants delivered at 26–31 weeks, for example, show coordinated facial expressions in response to heel prick, although these are immature compared to older infants. Four-D images of the fetus have also been reported to show fetuses ‘scratching’, ‘smiling’, ‘crying’ and ‘sucking’ at 26 weeks of gestational age. Although these later behavioural responses are not spinal cord reflexes, the responses are still unlikely to involve higher cortical centres. An anencephalic fetus withdraws from noxious stimulation, demonstrating that this response is mediated at a subcortical level. Similarly, infants with significant neonatal neurological injury due to a parenchymal brain injury respond to noxious stimulation with a pattern of behavioural reactions similar to infants without brain injury."