During pregnancy, a woman's body undergoes massive cardiovascular adjustments to support the developing foetus. The most striking change is a dramatic expansion in blood volume. Plasma volume increases by about 40 to 50 percent, while red blood cell mass increases by only 20 to 30 percent.
This uneven expansion creates a condition known as physiological anemia or hemodilution. Because the fluid portion of the blood increases much faster than the cells, laboratory tests show a lower concentration of hemoglobin and red blood cells. It is not a true deficiency of iron, but rather a state of being watered down. Recognizing this normal shift prevents midwives from panicking over mild drops in hemoglobin during routine antenatal booking visits.
While hemodilution accounts for mild drops in hemoglobin, true pathological anemia stems from specific underlying causes. In Nigerian clinical practice, iron deficiency remains the leading culprit, driven by the high demands of the growing foetus and placenta coupled with poor dietary intake.
Other notable causes include:
Risk factors multiplying these threats include closely spaced pregnancies, teenage pregnancies, multiple gestations, and low socioeconomic status limiting access to nutritious food.
Anemia often develops insidiously, allowing pregnant women to adapt to mild drops in hemoglobin. As the condition worsens, classic signs emerge. Midwives must watch out for pallor of the conjunctivae, nail beds, and palms, alongside complaints of generalized fatigue, shortness of breath on exertion, palpitations, and dizziness.
Left unmanaged, severe anemia threatens both mother and baby.
| Maternal Complications | Foetal Complications |
|---|---|
| Heart failure | Intrauterine growth restriction |
| Postpartum hemorrhage | Premature birth |
| Increased infection risk | Low birth weight |
| Higher maternal mortality | Fetal distress and hypoxia |
A tired, poorly oxygenated myocardium struggles to cope with the extra load of labor, making postpartum hemorrhage life-threatening even with normal blood loss.
Early detection is the cornerstone of effective management. Every woman must have her hemoglobin or packed cell volume checked at her first booking visit, repeated at 28 weeks, and again at 36 weeks.
According to World Health Organization standards adopted in many settings:
A reading below 7.0 g/dL signals severe anemia, requiring urgent medical intervention. Midwives should also review red blood cell indices when available to differentiate microcytic iron deficiency from other blood disorders.
Preventing nutritional anemia is far more effective than treating it once established. Antenatal care clinics must prioritize routine supplementation and education.
When routine prevention fails and mild-to-moderate anemia develops, active therapeutic measures begin. Oral iron therapy remains the first-line treatment. Midwives must counsel women on expected side effects, such as dark stools and mild constipation, to ensure compliance.
To enhance absorption, oral iron is best taken between meals or with a source of vitamin C, while substances like tea, coffee, and milk should be avoided at the same time.
If oral iron fails due to gastrointestinal intolerance or malabsorption, or if the pregnancy is too far advanced in the third trimester with significant anemia, parenteral iron (intravenous infusion) is prescribed. Intravenous iron bypasses the gut, rapidly replenishing iron stores with fewer digestive complaints.
Severe anemia (hemoglobin below 7.0 g/dL) is an obstetric emergency, particularly when diagnosed in the late third trimester or close to expected delivery. The compromised myocardium cannot handle the stress of labor or postpartum blood loss.
Midwifery actions include: