Umbilical cord blood gas
A trained midwife double clamped the umbilical cord within three minutes of birth (minimum distance between clamps = 10 cm). Blood samples were taken from both the umbilical artery and vein using a pre-heparinized 1 mL syringe. The partial pressure of carbon dioxide (PCO2), partial pressure of oxygen (PO2), oxygen saturation, and pH of both samples were analyzed using a GEM Premier 4000 blood analyzer (GEM Premier 4000: Instrumentation Laboratory, Bedford, MA,)20.