About Baby Head Circumference Percentiles
Head circumference (the distance around the largest part of the head) reflects brain growth. Rapid head growth or slow head growth can sometimes indicate health issues that need attention.
What this percentile means
A head circumference percentile compares your baby’s measurement with other babies of the same age and sex in the WHO standard group. A 70th percentile result means the head circumference is larger than about 70% of peers and smaller than about 30% of peers. The goal is not to “hit” a specific percentile, but to see steady growth over time.
Typical healthy range
Many healthy infants track between roughly the 3rd and 97th percentiles. Some babies naturally have larger or smaller head sizes due to family traits. A stable curve is typically reassuring, while sudden changes across multiple percentile lines can be a reason to check in with a clinician.
When to talk to a pediatrician
Consider seeking medical advice if you see a persistent rapid increase or decrease in percentile, or if there are symptoms such as vomiting, a bulging soft spot, unusual sleepiness, seizures, or developmental concerns. Your pediatrician can evaluate head growth together with physical exam and medical history.
How to measure correctly?
- Use a flexible tape measure (non-stretchable).
- Wrap it around the widest part of the head: just above the eyebrows, above the ears, and around the most prominent part of the back of the head.
FAQ
Why is head circumference measured?
Head circumference is a proxy for brain growth in early childhood. Clinicians track it to ensure growth is progressing steadily and to identify patterns that might need further evaluation.
What is a typical healthy range for head circumference percentiles?
Many healthy babies track between about the 3rd and 97th percentiles. A consistent pattern over time is usually more important than the exact number at one visit.
How do I measure head circumference correctly?
Use a flexible tape measure and wrap it around the largest part of the head: above the eyebrows and ears, and around the back of the head where it is most prominent. Measure snugly but not tight, and repeat for consistency.
When should I talk to a pediatrician about head growth?
Discuss if the percentile changes sharply across visits, if head growth seems unusually fast or slow, or if there are symptoms such as vomiting, bulging fontanelle, seizures, or developmental concerns. Your clinician can interpret head growth in context.