Laboratory Changes in Pregnancy
PARAMETER	EFFECT
Albumin and Total Protein	Decrease by 1 mg/dL to 3 and 6 mg/dl, respectively. Dilutional
Alkaline Phosphatase	Increases due to output by the placenta.
Bicarbonate (serum)	Decreases to about 20meq. Decreased ability to buffer acid loads. Other electrolyte levels should be normal.
Blood Urea Nitrogen	Should be < 14 mg/dL
Creatinine	Should be < 0.8 mg/dL, mean is 0.5 mg/dL
Creatinine Clearance	Increases by 50% to about 150 cc/min.
Creatinine Kinase-Myocardial	May be elevated after Cesarean section. The MB fraction makes up 6% of the total enzyme from the uterus and placenta.
D-Dimer	May be elevated in normal pregnancy. Negative value may be useful as in the non-pregnant population.
Erythrocyte Sedimentation Rate	Elevated. No clinical utility during pregnancy.
Fibrinogen	Elevated.
Glomerular Filtration Rate	50% increase can shorten the half-life of medications.
Hemoglobin	Decreases to 10-12 g/dL. Red cell mass increases less than plasma volume leading to a normal dilutional anemia of pregnancy.
Leukocyte Count	Slight Increase. Mean 8-10 and up to 14x10^9/L after delivery.
pCO2	Decreases to 28-32 mmHg
pH	Mildly alkalotic. Tends to run 7.44
Plasma Oncotic Pressure	Decreases. Women are more susceptible to non-cardiogenic pulmonary edema in the setting of infection, preeclampsia, surgery, tocolysis with beta-adrenergic agonists, or volume overload.
Platelets	No change.
pO2	Increases slightly due to hyperventilation and "blowing off" of pCO2.
Thyroid Labs (TSH, Free T4, Free T3)	No change. Free hormones may be elevated during the first trimester in 40% of women with hyperemesis gravidarum.
Transaminases and Bilirubin	No change.
Urine Protein - 24 Hour Collection	Up to 300 mg is normal.