Rapid Head Growth in Infants: When to Seek Further Evaluation

Infant head circumference

Hello Doctor, my baby was born on May 2, 2022 (a boy).
His height and weight are gradually increasing, but his head circumference is growing quite rapidly.
On September 3 (4 months and 1 day old), his weight was 6.7 kg, height was 63 cm, and head circumference was 42.4 cm.
On September 14 (4 months and 12 days old), his weight was 7.1 kg, height was 62.6 cm, and head circumference was 42.9 cm.
On September 27 (4 months and 25 days old), his weight was 7.2 kg, height was 63 cm, and head circumference was 43.5 cm.
On October 3 (5 months and 1 day old), his weight was 7.3 kg, height was 65.1 cm, and head circumference was 44.2 cm.
My baby boy's height and weight are between the 3rd and 97th percentiles.
However, his head circumference is already 44.2 cm at just over 5 months old (the internet states that the head circumference for a 5-month-old baby is between 40.3 and 44.8 cm), which is approaching the 97th percentile.
In a few days, it may exceed the 97th percentile.
When my baby was born, a cranial ultrasound was performed, and aside from two small cysts, everything else was normal.
On October 3, a follow-up cranial ultrasound showed that the small cysts had disappeared, and there was no evidence of hydrocephalus, and intracranial pressure was normal.

I would like to ask the doctor:
1.
Given that a cranial ultrasound has been performed and is currently normal with no hydrocephalus, can we conclude that my baby simply has a larger head size without any intracranial pathology, such as tumors or achondroplasia?
2.
Is there a need for further examinations, such as a CT scan or MRI? If so, will these tests expose my baby to radiation?

Danxin de Baba, 40~49 year old female. Ask Date: 2022/10/04

Dr. Xiao Kaiwen reply Pediatrics

If an infant's head circumference is greater than the 97th percentile or shows a significantly rapid growth rate, a pediatrician will typically recommend a cranial ultrasound examination.
If an experienced pediatrician conducts an evaluation and finds no obvious issues, the infant will be monitored.
The focus will be on observing subsequent neurological development, such as developmental delays, excessive stiffness or weakness in the limbs, seizures, and signs of increased intracranial pressure (such as excessive crying, irritability, and frequent vomiting).
If any of these symptoms are present, further follow-up with cranial ultrasound and possibly more advanced imaging studies will be necessary.
Computed tomography (CT) exposes the patient to higher levels of radiation, whereas magnetic resonance imaging (MRI) does not involve radiation exposure.

Reply Date: 2022/10/04

More Info

Understanding rapid head growth in infants can be a source of concern for many parents, and it’s important to approach this topic with both caution and knowledge. Based on the information you've provided, your baby has shown a significant increase in head circumference over a short period, which has raised questions about potential underlying issues.
1. Head Circumference Growth: The growth of head circumference is an important parameter in pediatric health assessments. Generally, head circumference is measured to monitor brain growth and development. The normal range for head circumference varies by age and sex, but for a 5-month-old boy, the average head circumference is typically around 40.3 cm to 44.8 cm. Your baby’s head circumference of 44.2 cm is indeed approaching the 97th percentile, which can be concerning, but it does not automatically indicate a problem.
2. Previous Evaluations: You mentioned that your baby underwent a cranial ultrasound at birth and again at 10/3, which showed normal results with no signs of hydrocephalus or other abnormalities. The disappearance of the small cysts is also a positive sign. Ultrasound is a useful tool for assessing brain structure in infants, particularly in the first year of life, as their skulls are still soft and allow for imaging.
3. Further Testing: Given that the ultrasound results are normal, it is reasonable to consider that your baby may simply have a larger head size without any pathological conditions. However, if there are concerns about rapid growth or if there are other symptoms (such as developmental delays, irritability, or changes in behavior), further imaging may be warranted.
- MRI vs. CT Scan: An MRI (Magnetic Resonance Imaging) is often preferred for evaluating brain structure in infants because it does not involve radiation, unlike a CT (Computed Tomography) scan. MRI provides detailed images of the brain and can help identify conditions such as tumors or developmental anomalies. However, MRI often requires sedation in infants, which carries its own risks and considerations.
4. When to Seek Further Evaluation: If your baby continues to show rapid head growth or if you notice any concerning symptoms, it would be prudent to consult a pediatric neurologist. They can assess your child's growth patterns in the context of their overall development and health history.
5. Monitoring Growth: It’s also important to monitor your baby’s growth over time. If the head circumference continues to increase significantly beyond the 97th percentile, or if there are changes in behavior or development, this could warrant further investigation.
In summary, while your baby’s head circumference is on the higher end of the growth chart, the normal ultrasound results are reassuring. Continuous monitoring and consultation with a healthcare provider will help ensure that any potential issues are addressed promptly. If you have ongoing concerns, discussing the possibility of an MRI with your pediatrician or a specialist may provide peace of mind and further clarity regarding your baby's health.

Similar Q&A

Understanding Progressive Intracranial Enlargement in Infants: When to Seek Help

Hello, I would like to ask about progressive cranial enlargement. My baby is currently one year and two months old, born at 35 weeks and three days, weighing 2450 grams at birth. He appears to have a large head and a small face, but his head circumference is normal. His weight is...

Dr. Zhang Wenwang reply Pediatrics
Hello, if height and weight are maintaining the same growth curve, I believe there shouldn't be significant issues with growth. If there are concerns about brain disorders, you may consult a pediatric psychiatrist for a thorough evaluation. Wishing you health and happiness. ...

Understanding Growth Concerns in Preterm Infants: A Pediatric Guide

Hello Doctor: My son is currently 2 months old, born at 38 weeks gestation. At birth, he measured 43 cm in height, weighed 2.17 kg, and had a head circumference of 30 cm, which classifies him as a low birth weight infant (due to my wife's uterine embolization). A pediatricia...

Dr. Xiao Kaiwen reply Pediatrics
1. Your baby is classified as a low birth weight infant. Since the degree of low birth weight varies among infants, the timeline for "catching up to the growth curve on the pediatric growth chart" also differs. Pediatricians typically do not focus on this issue. What is...

Concerns About Infant Brain Ultrasound Results: Hydrocephalus or Development Issues?

Hello, Doctor. My child is 2 months and 2 days old and went to the pediatric clinic for vaccinations. The doctor assessed that there is weak neck support (head lag) and arranged for a brain ultrasound examination. The results indicated that there is a significant amount of hydroc...

Dr. Xiao Kaiwen reply Pediatrics
The results of the infant's brain ultrasound examination indicate that monitoring is sufficient, as there are no obvious signs of hydrocephalus or issues with brain tissue development. It is important to regularly measure the baby's head circumference; if there is a dis...

Assessing Growth Delays in Infants: Head Circumference and Height Concerns

Hello, my baby was delivered via cesarean section at 37 weeks and 1 day due to an abnormal fetal position (during prenatal check-ups, my placenta function was normal, and no abnormalities were found in the baby. However, during each check-up, the doctor mentioned that the baby&#x...

Dr. Lin Yishou reply Pediatrics
Dear Parent, regarding your question, a physician's office examination is necessary for a more accurate assessment. It is not possible to make a direct judgment based solely on written descriptions. Thank you for your message.