New insights into fetal pain.

Fetal pain is difficult to assess, because the main feature needed to spot pain, is the subject's capability of declaring it. Nonetheless, much can be affirmed about this issue. In this review we first report the epochs of the development of human nociceptive pathways; then we review since when they are functioning. We also review the latest data about the new topic of analgesia and prenatal surgery and about the scarce effect on fetal pain sentience of the natural sedatives fetuses produce. It appears that pain is a neuroadaptive phenomenon that emerges in the middle of pregnancy, at about 20-22 weeks of gestation, and becomes more and more evident for bystanders and significant for the fetus, throughout the rest of the pregnancy.