White Blood Cell Count
Pregnancy is associated with a physiologic neutrophilic leukocytosis. Values rise progressively with gestation and peak during labor and the immediate postpartum period.
| Units | Nonpregnant Adult | 1st Trimester | 2nd Trimester | 3rd Trimester |
|---|---|---|---|---|
| x10³/mm³ (x10³/µL) | 3.5 – 9.1 | 5.7 – 13.6 | 5.6 – 14.8 | 5.6 – 16.9 |
| x10⁹/L | 3.5 – 9.1 | 5.7 – 13.6 | 5.6 – 14.8 | 5.6 – 16.9 |
Causes of elevated WBC (leukocytosis)
- Normal pregnancy neutrophilia
- Labor and postpartum response
- Infection (UTI, pyelonephritis, pneumonia, chorioamnionitis)
- Stress response (pain, trauma)
- Corticosteroid exposure
- Preeclampsia/HELLP
- Hyperthyroidism
- Dehydration/hemoconcentration
- Hematologic malignancy (rare)
Causes of low WBC (leukopenia)
- Viral infections (influenza, EBV, CMV, COVID-19)
- Bone marrow suppression (medications, chemotherapy)
- Autoimmune disorders
- Nutritional deficiencies (B12, folate, copper)
- Hypersplenism
- Aplastic anemia
- Severe sepsis
References
- Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies: a reference table for clinicians. Obstet Gynecol. 2009;114:1326–31. PMID: 19935037.