MCQ Detailed View

At birth, the human brain is already a highly developed organ, though smaller than that of an adult. The average brain weight of a newborn baby is about 400 grams. This represents nearly 10% of the infant’s total body weight, which is proportionally much larger than in adults, where the brain accounts for only about 2% of body weight.

The newborn brain grows at a remarkable pace in the early years. By the age of 1 year, the brain almost doubles in weight, reaching around 900 grams. By the age of 3 years, it achieves nearly 80–90% of its adult size, reflecting the rapid growth of nerve cells, synaptic connections, and myelination processes.

This early growth is essential because the brain is responsible for controlling vital functions such as breathing, movement, sensory processing, and the beginnings of speech and learning. The rapid increase in size and weight reflects the development of countless neuronal connections and the strengthening of brain networks needed for learning and memory.

Nutrition plays a vital role in brain development. Breast milk provides essential fatty acids, proteins, and micronutrients that support healthy growth. A lack of proper nutrition, infections, or oxygen deficiency during this critical period can negatively impact cognitive and physical development.

In comparison, an adult human brain weighs about 1,300–1,400 grams, which is more than three times the weight of a newborn’s brain. Despite this size difference, the newborn’s brain already contains almost all the neurons it will ever have; growth mainly comes from the expansion of connections and supporting structures.

Thus, the correct answer is 400 grams (Option B). This weight reflects the remarkable beginning of a lifelong process of brain development that continues well into early adulthood.