Basophil Count — Whole Blood
| Units | Nonpregnant Adult | 1st Trimester | 2nd Trimester | 3rd Trimester |
|---|---|---|---|---|
| x10³/mm³ x10³/µL |
0–0.2 | 0–0.1 | 0–0.1 | 0–0.1 |
| x10⁹/L | 0–0.2 | 0–0.1 | 0–0.1 | 0–0.1 |
Basophils are normally very low or undetectable in pregnancy. Pregnancy does not cause basophilia; any elevation should be evaluated.
Normal physiology during pregnancy
- Basophils remain low or undetectable throughout pregnancy.
- Mild decreases may occur due to:
- physiologic hemodilution
- neutrophil-predominant leukocytosis
- steroid-mediated immune modulation
- Pregnancy does not cause basophilia.
Causes of HIGH basophils (basophilia)
Allergic / atopic disease
- Allergic rhinitis
- Asthma
- Chronic atopy
Chronic inflammatory or autoimmune disease
- Rheumatoid arthritis
- Ulcerative colitis
- Chronic dermatitis
Endocrine causes
- Hypothyroidism (classic cause)
Hematologic disease
- Chronic myelogenous leukemia (CML)
- Polycythemia vera
- Other myeloproliferative neoplasms
Infectious causes
- Varicella
- Smallpox
Other causes
- Splenectomy
- Hypersensitivity reactions
- Estrogen therapy (rarely relevant during pregnancy)
Causes of LOW basophils (basopenia)
- Physiologic pregnancy-related hemodilution
- Acute illness or stress response
- Hyperthyroidism
- Cushing syndrome or corticosteroid use
- Chronic urticaria
- Severe allergic reactions (consumption)
Clinical notes
- Basophils usually comprise a very small percentage of circulating leukocytes.
- Undetectable basophils are normal in pregnancy.
- Persistent basophilia warrants evaluation for hematologic disorders if allergy or thyroid disease is excluded.
References
- Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies. Obstet Gynecol. 2009;114:1326–31.