Inclusion Criteria:  pregnant patients at term (36th to 40th week of gestation) scheduled for elective caesarean section under spinal anesthesia.  Exclusion Criteria:  age <18 years American Society of Anesthesiologists score >3 cardiac arrhythmias or aortic regurgitation pregnancy-induced hypertension pre-eclampsia body mass index (BMI) > 35 kg/m2 foetal complications coagulation disorders or contraindication to neuraxial block emergency surgery preoperative infection patient's refusal