<prompt> The increase in head circumference in 1st year of life is what percentage of head circumference at birth15663390  <response>: Head circumference at birth 35cm in HC in 1st 3 months 2cmmonth 6cm in HC in 4-6 months 1cmmonth 3cm in HC in 7-6 months 0.5cmmonth 3cmBy 1st year, HC 35633 47cm in HC 47 - 35cm 12cm of in HC in 1st year of life 1235 × 100 33 