Pain impulses are blocked with in the back bone and they do not reach the brain. Epidural is an anesthetic delivered by injection near the lower spine. It numbs the body below the injection, allowing woman to remain alert but more comfortable during contractions of childbirth.
Epidural anesthesia and spinal anesthesia are called regional anesthetics because they anesthetize one specific region of the body. These are popular for childbirth because the pain relief is excellent and very little medication reaches the baby. The medications used here include local anesthetics (e.g. novocaine-like medications such as bupivacaine) and narcotics. These medications block the nerves that carry sensations of pain from the uterus and cervix back to the spinal cord in the back bone and brain. This method allows you to be awake and alert, yet relatively free of pain. Although rare, side effects and complications do exist (see section on "Side effects and complications')