Greatest amount of cranial growth occurs by:

The head of a newborn is about 55%–60% of adult head breadth, 40%–50% of adult height and 30%–35% of adult depth. The cranium to-face ratio in a newborn is 8:1.  With continued development, especially of the lower face, the ratio changes to 1:2 in adulthood. By the age of 8 years, the brain is nearly 95% of its adult size. This rapid growth spurt is followed by a plateau phase of slow but steady growth that continues till adulthood.