Xie W, et al. - Since calcitonin gene-related peptide (CGRP) has been reported to play a key role in the development of peripheral sensitization and to have an association with enhanced pain, researchers presumed that CGRP 4218T/C polymorphism is associated with the variability in fentanyl consumption for post-cesarean analgesia. In this study, among patients who presented for elective cesarean delivery, the presence of C/C genotype was indicated to be possibly associated with a reduced sensitivity to fentanyl analgesia and/or increased pain perception. Furthermore, patients with C/C genotype were more willing to use PCEA fentanyl to manage their pain.