Médecine de la Reproduction


Development of pain pathways in the human foetus Volume 12, issue 2, avril-mai-juin 2010

Laboratoire d’anatomie et de cytologie pathologiques, Pavillon Jacques-Delarue, CHR, hôpital Charles-Nicolle, 1, rue de Germont, 76031 Rouen cedex, France

During embryo-fetal life, early responses to noxious stimuli consist in muscle contraction called spinal reflex, that is early detectable then obvious and appropriated after the 26th week of amenorrhea (WA). The way of thermic pain sensitivity, mediated through the spinothalamic way, is in place after 20 WA and becomes functional when it connects to different cortical areas involved in the integration of pain, i.e., after 24 weeks. It was at this time that the medullary relay become mature through the establishment of local neuromodulator circuits. The emotional dimension of pain experience would be functional after 30 weeks, when the vigilance states appear and when the memory circuits and interhemispheric callosal connections take place. It is accepted by most authors that the functional maturation of all these structures is necessary for conscious perception of pain whose presence would fall just after the start of the second half of pregnancy.