Pregnant women with preeclampsia undergoing elective CS in will be included in the study. All patients participating in the study will be randomly divided into two groups; magnesium sulphate group (study group) and placebo group (control group). Patients in the study group will receive epidural 20 ml levobupivacaine hydrochloride 0.5% plus 5 ml magnesium sulphate 10% (500 mg) while patients in the control group will received epidural 20 ml levobupivacaine hydrochloride 0.5% plus 5 ml saline 0.9%.