What is the relationship between the chest circumference and head circumference of a 12-month-old infant?

In infants, particularly around the age of 12 months, a typical developmental pattern is observed in the relationship between chest circumference and head circumference. Generally, by the time an infant reaches 12 months, the head circumference often begins to approximate the chest circumference, and in many cases, chest circumference can equal or even surpass head circumference.

In the first months of life, head circumference is usually larger than chest circumference as the brain grows rapidly. However, as the child grows, the growth in the chest and torso begins to catch up. By the 12-month mark, it is quite common for the measurements to be similar with some children showing equal sizes. This reflects normal growth patterns, and it underscores the developmental changes that occur as a child matures.