In a matchless analgesic efficacy during childbirth, epidurals also offers the possibility of a secure obstetrical gesture because without general anesthesia, inhalation great purveyor in these women with full stomach. These advantages explain the considerable growth in the number of epidurals performed in obstetric work in France over the last thirty years. However, this analgesia technique will soon be implicated in the alterations of obstetric mechanics, its effects depend primarily on the nature and concentration of the products used.