This will be a multi-center, prospective, single-blind randomized trial of two types of IV fluids for maintenance hydration during labor. This study will be conducted at 4 sites: Reading (Reading Hospital), Allentown (Lehigh Valley), St. Luke Hospital and Hershey (Penn State College of Medicine). It will include 1524 pregnant women at ≥ 36 weeks presenting in spontaneous labor for anticipated delivery.