Analgesic Additives to Epidural Bupivacaine in Normal Labor

The aim of the study will be to compare the role of Dexmedetomidine, Nalbuphine and fentanyl as additives to epidural bupivacaine in painless vaginal delivery as regard of effectiveness analgesia and maternal safety.

Inclusion Criteria:>/= 18 years of ageAmerican Society of Anesthesiologists (ASA) Physical Status 2 or 3Full term pregnancy (>37 gestational weeks)Planning vaginal deliveryPlanning epidural labor analgesiaVertex presentationExclusion Criteria:Patient refusal to epidural analgesia,Contraindications of epidural analgesia (coagulopathy, local infection, vertebral deformity)Allergy to study agents (hypersensitivity to bupivacaine, Nalbuphine, fentanyl or dexmedetomidine)hemodynamic instability, severe aortic or mitral stenosis)Severe pre-eclampsia,Breech presentationsAntepartum hemorrhageCephalopelvic disproportionBody mass index ≥40 kg/m2.Uncontrolled systemic comorbidities [i.e., diabetes, hepatic, renal or cardiac]Known or suspected fetal abnormalitiesInability to communicate or participate in study procedures