Epidural Analgesia and Troubles of Fetal Cardiaq Rythm : Effect of the Systemic Transfer of Ropivacaine and Sufentanil

Inclusion Criteria: * 18 years old or more * nulliparous \_ one fetus * head first * spontaneous labor * epidural analgesia * no fetal cardiac rhythm abnormalies before the epidural analgesia * no active management of labor during 30 minutes after the epidural analgesia induction * at term * signature of the consent form Exclusion Criteria: * pathological pregnancy * low maternal blood pressure during the 30 minutes after the epidural analgesia * uterin contraction which last for 5 minutes or more * more than 6 uterin contractions during a 10 minutes period * Ropivacaine contraindication * sufentanil contraindication