Physiologic Changes During Pregnancy

Increases

Blood volume, heart rate, and cardiac output rise by 35% to 50%, peak at 32 weeks' gestation; further increase by 20% in twin pregnancies
Alkaline phosphatase levels rise three- to fourfold because of placental production
Clotting factors I, II, V, VII, VIII, X, and XII
Ceruloplasmin level
Transferrin level

Decreases

Gallbladder contractility
Hemoglobin level (because of volume expansion)
Uric acid level
Albumin and total protein levels
Antithrombin III and protein S level
Systemic vascular resistance
Modest decline in blood pressure

No Changes

Liver transaminase levels (aspartate aminotransferase, alanine aminotransferase)
γ-Glutamyl transferase (GGT) level
Bilirubin level
Prothrombin time
Platelet count (or slight decline)