## **Core Concept**
The World Health Organization (WHO) provides criteria for defining anaemia in various age groups, including infants. Anaemia in infants is a significant concern due to its impact on growth, development, and overall health. The definition of anaemia in infants is primarily based on haemoglobin (Hb) levels.

## **Why the Correct Answer is Right**
According to the WHO criteria, anaemia in infants at 6 months of age is defined as a haemoglobin level less than 11 g/dL. This criterion is established based on the expected normal haemoglobin range for this age group, taking into account factors like nutritional status, common causes of anaemia, and the physiological changes that occur during infancy.

## **Why Each Wrong Option is Incorrect**
- **Option A:** 8 g/dL - This value is too low for defining anaemia in 6-month-old infants. A haemoglobin level of 8 g/dL would indicate severe anaemia.
- **Option B:** 10 g/dL - While close, this is not the correct threshold according to the WHO criteria for this age group.
- **Option D:** 12 g/dL - This value is actually higher than the threshold for defining anaemia in 6-month-old infants.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the definition of anaemia varies by age and, in some cases, by gender. For infants at 6 months, a haemoglobin level less than 11 g/dL is considered diagnostic of anaemia. This is crucial for pediatricians and healthcare providers to identify and manage anaemia early.

## **Correct Answer:** . 11 g/dL.