A need exists to define the best local anesthetic and technique for pain relief in early labour. We suggest that calculating the molar Median Effective Dose for bupivacaine, levobupivacaine and ropivacaine given both by the intrathecal (as a combined spinal epidural and epidural routes) would provide a valid comparison between the pain relieving properties of all three drugs, from which a reasoned assessment of side effects can be made.