Anemia in Pregnancy
Physiological changes in pregnancy—specifically an increase in plasma volume disproportionate to the increase in red cell mass (physiologic hemodilution)—make anemia common. WHO defines anemia in pregnancy as Hb < 11.0 g/dL in the first and third trimesters, and Hb < 10.5 g/dL in the second.
Common Causes
- Iron Deficiency Anemia (IDA): The most common cause (approx. 75%). Due to increased iron demand for the expanding red cell mass, fetus, and placenta.
- Folate Deficiency: Increased demand leads to megaloblastic anemia. Supplementation is critical for neural tube defect prevention.
- Vitamin B12 Deficiency: Rare, but can occur in vegetarians/vegans or those with malabsorption.
Diagnostic Markers
| Marker | Iron Deficiency Finding |
|---|---|
| MCV | Usually low (microcytic). |
| Ferritin | The most reliable marker (low < 30 µg/L). |
| TIBC | Elevated. |
High-Yield Exam Pearl:
- Prophylaxis: Routine iron supplementation is recommended in many regions to meet the high iron requirements of pregnancy.
- Treatment: Oral iron is first-line. Intravenous (IV) iron (e.g., ferric carboxymaltose) is reserved for patients who are intolerant to oral iron, have malabsorption, or require rapid Hb elevation in late pregnancy.