Inclusion Criteria:  Pregnant women age 18 - 50 years old Patients scheduled for cesarean delivery at >34 weeks gestation Patients who failed trial of labor and require cesarean delivery  Exclusion Criteria:  Patients with spontaneous or operative vaginal delivery Patients with hemoglobinopathies (qualitative defects, sickle-cell anemia) and hemoglobin synthesis disorders (quantitative defects such as thalassemia) Patients with peripheral vascular diseases and skin conditions that affect blood vessels in the digit Patients with hyperbilirubinemia