Head circumference growth must be closely monitored in children, from their birth to the age of 2. It is, in fact, a significant indicator of a baby's healthy development. If the circumference is too small, it can demonstrate a child's failure to thrive. On the other hand, if it is too large for the baby's age, it can indicate hydrocephalus, an excessive dilation of certain areas of the brain that can lead to both mental and motor disorders. The head circumference is measured with a tape measure, positioned on the forehead continuing laterally around the head to encircle the very back of the occiput. Growth charts including these measurements along with those of weight and height, recorded in a child's case file, enable doctors to monitor their evolution to compare with normal values.