Microcephaly and Macrocephaly


These guidelines have been produced to guide clinical decision making for general practitioners (GPs). They are not strict protocols. Clinical common-sense should be applied at all times. These clinical guidelines should never be relied on as a substitute for proper assessment with respect to the particular circumstances of each case and the needs of each patient. Clinicians should also consider the local skill level available and their local area policies before following any guideline.

Please discuss with the General Paediatric Registrar if the child has:

  • a bulging fontanelle
  • abnormal eye movement
  • excessive vomiting, sleepiness, irritability.


Variation in head shape or size is a common reason for referral to Paediatric outpatient clinics.

Microcephaly is a rare condition in which an infant’s head is significantly smaller than expected. It can be congenital or acquired. There are many processes that can disrupt brain development and growth and lead to microcephaly. Children with microcephaly generally have neurodevelopmental difficulties. Microcephaly is indicated by a head circumference < 3rd percentile for age, a head circumference that is disproportionately small when compared to other growth parameters or serial head circumference measurements that cross two or more centile lines downwards

Macrocephaly is when the head circumference is > 98th percentile for age or disproportionately large when compared to other growth parameters. Benign / familial macrocephaly is the most common cause however there are other significant causes that should be excluded. A head circumference that crosses two or more centile lines, even if it has not crossed the 98th percentile for age, should be assessed.

Pre-referral investigations

No specific pre-referral investigations are required. 

Pre-referral management

Monitor head circumference with serial measurements. For children born before 37 weeks gestation, please use Fenton’s growth chart and plot as per corrected age. 

When to refer

  • Head circumference not tracking appropriately along growth percentiles
  • Concerns regarding development or muscle tone
  • Dysmorphic features
  • Small or closed anterior fontanelle. 

How to refer

  • Routine non-urgent referrals from a GP or a Consultant are made via the Central Referral Service
  •  Routine non-urgent referrals from private hospitals go to the PCH Referral Office
  • Urgent referrals (less than seven days) should be discussed with the on call general paediatric registrar.

Essential information to include in your referral

  • Birth history
  • Growth parameters and percentile charts, especially head circumference. For children born before 37 weeks gestation, please use Fenton’s growth chart and plot as per corrected age.
  • Physical examination findings
    • Skull shape, sutures and fontanelles
    • Eye movement
  • Dysmorphic features
    • Developmental history
    • Family history
  • Head circumference of both the parents in case of macrocephaly.

Useful resources

Reviewer/Team: Dr Andrew Martin, Dr Ciara Peake, Dr Rebecca Cresp, Dr Divyesh Mehta
Last reviewed: Dec 2021

Next review date: Dec 2024
Endorsed by:
 Dr Andrew Martin, General Paediatrics Head of Dept (fast track) Date:  Dec 2021

This document can be made available in alternative formats on request for a person with a disability.

Referring department

General Paediatrics