Immunoglobulin A (IgA), Serum
Immunoglobulin A (IgA) is the primary antibody involved in mucosal immunity. During pregnancy, serum IgA levels typically show a mild decrease due to plasma volume expansion and immune modulation.
| Units | Nonpregnant Adult | 1st Trimester | 2nd Trimester | 3rd Trimester |
|---|---|---|---|---|
| mg/dL | 70 – 350 | 21 – 317 | 30 – 306 | 43 – 319 |
| g/L | 0.70 – 3.50 | 0.21 – 3.17 | 0.30 – 3.06 | 0.43 – 3.19 |
Clinical note: Mild reductions in IgA during pregnancy are typically physiologic and not associated with increased maternal infection risk.
Causes of low IgA in pregnancy
- Selective IgA deficiency (most common primary immunodeficiency)
- Physiologic hemodilution of pregnancy
- Protein loss (nephrotic syndrome, protein-losing enteropathy)
- Immunosuppressive medications
- Malnutrition or malabsorption (celiac disease, inflammatory bowel disease)
- Congenital immunodeficiency syndromes
- Liver disease with impaired immunoglobulin synthesis
Causes of high IgA in pregnancy
- Chronic inflammation or chronic infection
- Liver disease (cirrhosis, alcoholic liver disease)
- Autoimmune disorders (e.g., rheumatoid arthritis, systemic lupus erythematosus)
- IgA nephropathy
- Plasma cell dyscrasias (rare)
- Chronic pulmonary disease or smoking
References
- Lockitch G. Handbook of Diagnostic Biochemistry and Hematology in Normal Pregnancy. CRC Press; 1993.
- Abbassi-Ghanavati M, Greer LG, Cunningham FG. Obstet Gynecol. 2009.