How to Measure Head Circumference

Measuring an infant's head circumference is an important part of monitoring their development and health, especially within the first year. This basic measurement can give doctors and parents valuable insights into a baby's growth pattern and neurological condition. Learning the proper technique for measuring infant head circumference is essential.

This in-depth guide covers why head circumference measurements are important for infants. Along with some recommendations on when medical professionals and parents should track head growth.

And step-by-step instructions on how to precisely measure a baby's head size. You’ll have confidence measuring your infant’s head and understanding if their growth patterns warrant further medical investigation after reading this resource.

Why Measuring Head Circumference

Monitoring your infant's head circumference measurement during regular checkups allows:

1. Identification of abnormal growth rates that could indicate developmental problems
2. Diagnosis of many disorders such as macrocephaly, microcephaly, and hydrocephalus  
3. Tracking your baby’s brain development in the early years
4. Comparison with growth percentile charts to classify size as proportional 

Head measurement provides more meaningful data than weight or length at young ages. Sudden changes in your child’s head growth curve warrant further medical investigation.

When to Measure Infant Head Circumference

The American Academy of Pediatrics (AAP) recommends physicians measure head circumference at birth, by 1 month, 2 months, 4 months, 6 months, 9 months, 12 months, 15 months, 18 months, and 24 months. They plot measurements on standard charts.

You can also measure your baby’s cranial size at home between pediatric visits using the technique below. Try monthly for the first 6 months then every 2-3 months thereafter during the first 3 years when brain growth is most rapid.    

Compare your readings to previous records and growth charts. Notify your pediatrician promptly about unusual growth between scheduled well-child exams.

How to Measure Baby’s Head Circumference Step-by-Step 

Preparing Infant for Head Measurement   

To measure head size, your baby should be calm and relaxed. Crying tightens the head muscles and yields inaccurate sizing. Follow these tips for best results:  

• Feed/change diaper first - A fed, dry baby will be most peaceful 
• Hold securely or lay flat - Proper positioning prevents wiggling
• Remove hair bands, bows, hats - Anything on the head affects measurement
• Average room temperature - Keep them comfortable  

With some soothing motions and distractions, most infants adapt well for the short circumference measurement.

You’ll need a flexible measuring tape marked in centimeters. Inch tapes or stiff rulers don’t conform properly around the head shape. Follow these head circumference measurement techniques:

Step 1: Position the Tape 

• Place the tape across your baby’s forehead, just above the eyebrows and ears
• Ensure the tape sits flat on the head, not twisted or tangled in hair
• Check it's level from one side to the other  

Step 2: Wrap Measuring Tape  

• Gently wrap the tape around back of your baby’s head
• Bring the other end of the tape across the forehead to meet the start 
• The endpoints should align evenly  

Important: Do not pull or tighten the tape which could compress soft spots 

Step 3: Read Measurement

• Where the tape overlaps itself at the forehead, read measurement   
• Record circumference size to the nearest tenth of a centimeter
• Round down if the decimal fraction is less than 0.05 cm 
• Round up if 0.05 cm or higher

Be very precise. Even subtle changes in head circumference are significant at this stage of rapid infant brain development.  

Step 4: Repeat Measurement  

To ensure accuracy:  

• Carefully unwrap, reposition, and retake measurement 
• Record new size
• Compare readings and if within 0.5 cm, average the 2 measurements   

Consistent technique and precise tape placement are vital for reliability. With some practice, parents can track changes as small as 1 cm in head growth patterns.

Interpreting Infant Head Circumference Readings

Once you’ve recorded your baby’s head measurement, compare it against standard growth charts. Pediatricians use advancement along percentile curves to assess development. 

1. If your baby's head circumference jumps above the 90th percentile or falls below the 10th percentile since the last visit, consult your doctor. Explore the reasons behind this accelerated or slowed growth with a doctor. 
2. Macrocephaly or microcephaly diagnoses involve head sizes above the 97th or below the 3rd percentiles respectively.
3. Your pediatrician will order further tests like ultrasounds or MRIs if needed to determine any underlying conditions.

While genetics contribute toward head size, abnormal growth patterns or sudden changes can also indicate:  

1. Neurological conditions like autism spectrum disorder or cerebral palsy   
2. Brain injuries or bleeding within the skull during delivery
3. Congenital malformations of the brain structure
4. Delayed development of motor skills  

Early intervention maximizes outcomes for infants diagnosed through routine head measurements. That’s why consistent checks are so important.

Tips for Measuring babies’ Head Size at Home

With some patience, parents can successfully monitor head circumference at home between office visits:  

• Work together - One person distracts and comforts while the other measures
• Minimal clothing - Less bulk under tape improves accuracy  
• Multiple trials - Average 3-4 readings for best results
• Remain calm - Your tensions transmit, upsetting baby
• Use stickers - Reward cooperation with their favorite character 
• Be quick - Infants have short attention spans  
• Make comparisons - Compare your recorded measurements over time rather than relying on isolated readings

Consistent home monitoring spotlights growth patterns for discussion with your pediatrician. But leave formal diagnostic decisions and testing to the professionals. As they check with the head circumference percentile calculator for accurate readings.

Seek reference of head circumference for age at WHO

When to Seek Medical Guidance

While gentle fluctuations are normal, contact your doctor promptly for:

1. No noticeable head growth over 2-3 months  
2. Sudden huge jump in head size between readings
3. Consistently high or low percentile measurements  
4. Signs like bulging soft spots, vomiting, lethargy, irritability
5. Suspected injury from a fall or accident

Bring your home newborn head circumference measurements to appointments for in-depth analysis and interpretation. This is all based on your child’s health history and risk factors.

Why Head Circumference Matters

Measuring infant head circumference and monitoring it might seem trivial. Especially when you’re overwhelmed with the many tasks and milestones of early parenthood.

But unusually rapid or slow growth could provide an early warning to your pediatrician. This could be about possible developmental, neurological or physical conditions needing further evaluation.

Catching problems early in an infant’s brain development stages leads to the best prognosis from early intervention therapies. So take a few minutes periodically to whip out the head measuring tape.

Consistently tracking head size can give you both peace of mind or an early alert for additional tests.