Monocyte Count (whole blood)
Monocytes rise slightly in pregnancy as part of the physiologic increase in leukocytes and enhanced innate immunity.
| Units | Nonpregnant Adult | 1st Trimester | 2nd Trimester | 3rd Trimester |
|---|---|---|---|---|
| ×10³/mm³ ×10³/µL |
0.1 – 0.7 | 0.1 – 1.1 | 0.1 – 1.1 | 0.1 – 1.4 |
| ×10⁹/L | 0.1 – 0.7 | 0.1 – 1.1 | 0.1 – 1.1 | 0.1 – 1.4 |
Pregnancy physiology
- Mild monocytosis is common in pregnancy.
- Reflects increased innate immunity and inflammatory activity.
- Peak elevation typically in late pregnancy.
- Monocytes help support placental immune tolerance.
Causes of elevated monocyte count (monocytosis)
- Normal pregnancy (most common)
- Acute or chronic infections (TB, bacterial, viral)
- Inflammatory disorders (IBD, RA, SLE)
- Stress response, trauma
- Recovery from neutropenia
- Hematologic disorders (CML, myelodysplastic syndromes)
- Sarcoidosis
Cited references:
• Abbassi-Ghanavati et al., Obstet Gynecol 2009.
• Bain BJ. Blood Cells: A Practical Guide.
• Hoffman R. Hematology: Basic Principles and Practice.
Causes of decreased monocyte count (monocytopenia)
- Aplastic anemia / marrow suppression
- HIV infection
- Severe infections (overwhelming sepsis)
- Chemotherapy / radiation therapy
- Corticosteroid therapy
- Autoimmune suppression
- Stress hypercortisolemia
Cited references:
• Williams Hematology.
• Bain BJ — Morphology of blood and bone marrow.
• Abbassi-Ghanavati pregnancy laboratory ranges.
References
- Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies: a reference table for clinicians. Obstet Gynecol. 2009;114:1326-31.
- Bain BJ. Blood Cells: A Practical Guide. Wiley-Blackwell.
- Hoffman R, ed. Hematology: Basic Principles and Practice.