The head circumference of a 9-month-old baby is 47cm, which is generally not normal and a little on the large side.
Head circumference is an important indicator for monitoring the growth and development of infants, and can be measured using a soft ruler, from the most prominent point above the arch of the eyebrow backward through the highest occipital ridge, around the head for a week.
The average head circumference at birth is 33~34cm, and the growth of the head circumference in the first 3 months of the first year is equal to the growth of the head circumference in the next 9 months (6cm), which means that the head circumference at the age of 1 year is about 46cm, so the head circumference of a 9-month-old baby is 47cm, which is a little bit too big.
Continuous tracking and measurement of head circumference in infancy is more important than one measurement, and the size of the head circumference is related to the head circumference of both parents, and may also be related to calcium deficiency, genetic factors, intracranial tumors, etc., and if the head circumference grows too fast often suggests the possibility of hydrocephalus.
It is recommended to bring your baby to the doctor for another measurement, and if there is any abnormality, the cause should be clarified and targeted treatment should be given according to the doctor’s instructions.