PubMed1998
There has been debate recently as to whether the fetus can feel pain, a subject not readily amenable to research--not only are ethical issues involved, but the evaluation of pain felt by the fetus is also problematic, as it is unable to communicate intelligibly. A philosophical problem also arise concerning the definition of pain, as it is a phenomenon complicated by the presence of both emotional and experiential components. Moreover, there is the question of which anatomical structures are necessary for pain perception. However, some studies have been done, the most controversial of which having been performed during blood transfusion to anaemic fetuses, where the fetal blood cortisol concentration was shown to be higher in conjunction with hepatic vein needling than in conjunction with umbilical vein needling. Opinion differs in the research community as to the interpretation of these results, and whether stress response is equatable with pain. Most research in this field has been done on premature newborns in neonatal intensive care units, and some of the results can possibly be extrapolated to fetuses. Nervous system function in infants differs from that in adults, reflexes being more easily triggered in infants, for example, and thus it is difficult to distinguish pain response from reflexes. The effect of pain on the health status of the newborn is an important issue. Follow-up studies of premature infants have shown low birthweight and the need of neonatal intensive care to be correlates of divergent pain behaviour and acute pain is known to be associated with such untoward effects as tachycardia. It is important to bear in mind the possibility of fetal pain and provide appropriate pain relief, for example when surgery is performed in utero.