Pain in early labour is limited to dermatomes-
Labor pain caused by uterine contractions and cervical dilation is transmitted through visceral afferent sympathetic nerves entering the spinal cord from T10 - L1. Later in labor, perineal stretching transmits painful stimuli through the pudendal nerve and sacral nerves S2 - S4.
T11 T12 L1
S1 S3
L4 L5
L2 L3
Labour - normal, abnormal, malposition, malpresentation and their management