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Children's Health

Head circumference correlation to weight.



My 15 month old daughter weighs 18.4 lbs, height is 30 inches and head cir. is 42.75 cm. Her doctor is worried about her head size being below the scale. While I am concerned too I would think that you have to look at it inrelation to her weight, which is on the low side for her age as well. Is there a correlation between the two? Wouldn`t you see a smalled head circumference with a smaller weight child?



I think your daughter's doctor is correct in raising concern about her head circumference. As her doctor may have shown you on a growth chart, her weight is below the 5th percentile, meaning that very few little girls at 15 months of age weigh less than she does and over 95% of them weigh more. In contrast, her length is between the 25th and 50th percentiles, indicating that she she is close to average in length with other little 15-month-old girls. Her weight for length percentile, not surprisingly, is at the 5th percentile. She is very lean for her length compared to other little 15-month-old girls.

Having a nearly average length for her age, is very reassuring in that she is not receiving so few calories that she is unable to grow in length. It also indicates that a chronic health condition is unlikely to be the cause of her low weight gain.

In terms of her head circumference, she is even below the 3rd percentile for her age and gender. This may be because she inherited a tendency to have a smaller head from her parents. If both you and her father wear a small hat size and are small in stature, this may be the reason for her small head circumference.

If she has always had a small head circumference but on the same growth curse, there is less cause for concern. This may be her innate growth pattern.

However, if her head circumference has dropped in growth percentiles over time, this is concerning. I am thinking this must be the case if concern is only arising now at 15 months and not sooner. Normally, the brain grows most rapidly during the first two years of life. For that reason, the first 24 months of life are also known as the "brain growth spurt" period. This also explains why we measure head circumference throughout the first two years of life. Declining head circumference growth percentiles during this time may indicate failure in brain growth. Usually head circumference is the last measure of growth to decline in a child not taking in adequate nutrition for growth. Since her length is fine, the possibility of a problem in brain growth is greater.

Developmental progress is another window into brain development. Concern increases if developmental milestones are not being reached on time or the child loses developmental skills, for example, she was walking and now will only crawl.

I can only imagine how worrisome this must be for you! All parents want their children to be healthy and normal. Nothing may be wrong or perhaps there is something that needs to be diagnosed and treated.  If there is a condition that is causing a slowing in head growth and therapies with specialists would benefit your daughter, then you really do want to have a reasonable number of tests done to reassure yourself that all is well or begin the treatments she needs if there is a problem discovered. The first three years of life are the most important for providing extra services to young children that will help them do their best in school when they are older.

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Response by:

Mary M Gottesman, PhD, RN, CPNP, FAAN Mary M Gottesman, PhD, RN, CPNP, FAAN
Professor of Clinical Nursing
College of Nursing
The Ohio State University