How does the World Health Organization (WHO) classify anemia severity in adult men, non-pregnant women, and pregnant women based on hemoglobin levels?

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WHO Anemia Severity Classification by Hemoglobin Concentration

WHO defines adult anemia severity using hemoglobin cutoffs expressed in grams per liter (g/L). [1]

Adult Men (non-pregnant)

Mild anemia: hemoglobin 110–129 g/L (11.0–12.9 g/dL). [1]
Moderate anemia: hemoglobin 80–109 g/L (8.0–10.9 g/dL). [1]
Severe anemia: hemoglobin <80 g/L (<8.0 g/dL). [1]

Adult Non-pregnant Women

Mild anemia: hemoglobin 110–119 g/L (11.0–11.9 g/dL). [1]
Moderate anemia: hemoglobin 80–109 g/L (8.0–10.9 g/dL). [1]
Severe anemia: hemoglobin <80 g/L (<8.0 g/dL). [1]

Pregnant Women (trimester-specific)

First trimester

Mild anemia: hemoglobin 100–109 g/L (10.0–10.9 g/dL). [1]
Moderate anemia: hemoglobin 70–99 g/L (7.0–9.9 g/dL). [1]
Severe anemia: hemoglobin <70 g/L (<7.0 g/dL). [1]

Second trimester

Mild anemia: hemoglobin 95–104 g/L (9.5–10.4 g/dL). [1]
Moderate anemia: hemoglobin 70–94 g/L (7.0–9.4 g/dL). [1]
Severe anemia: hemoglobin <70 g/L (<7.0 g/dL). [1]

Third trimester

Mild anemia: hemoglobin 100–109 g/L (10.0–10.9 g/dL). [1]
Moderate anemia: hemoglobin 70–99 g/L (7.0–9.9 g/dL). [1]
Severe anemia: hemoglobin <70 g/L (<7.0 g/dL). [1]

Sources (1)

[1] Guideline 2024

Guideline on haemoglobin cutoffs to define anaemia in indiv…

World Health Organization (via NCBI Bookshelf)