According to the general developmental pattern, the head circumference of a 1-year-old baby is 43cm is normal. The normal range of head circumference for a one-year-old boy is 42.6~50.5cm, and for a one-year-old girl is 41.5~49.3cm. 43cm is within the normal range for both boys and girls. Within one year of age, head circumference growth in the first three months and the next nine months is the same, the average head circumference at birth is 34cm, between different children due to the influence of genes and other factors, head circumference development may be slightly different, but as long as it is in line with the law of growth, there is no need to worry. There are many factors that can affect the development of your baby’s head circumference, so we recommend that you go to a specialized children’s hospital to have a physical developmental examination and consult a professional doctor.