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Newborn and Infant Care

Small head circumference in my daughter



Our daughter is approximately 6 mos old and recently her doctor has told us that her head circumference is in the 12th percentile for her age. He is wanting us to bring her back in a month and if it continues to stay small he would like to do a CT scan to see if her skull has fused together too soon. Our child`s head is perfectly round and she still has her soft spots. My question is; what causes this and what are the long term effects of this problem. In all, how concerned should we be?


It must be very worrisome learning that something could be wrong. I hope that your baby's doctor did carefully re-measure her head size and verify that it is correctly plotted on the growth chart before expressing concern. This baby growth measurement is often done poorly.

Whether or not to be worried about about a baby's head growth is also a determined by whether or not there is a change in growth pattern and in light of the baby's heredity. For example, if your daughter's head growth has always been at the 12th percentile, meaning that her head size is larger than that of 12% of all 6 month old girls but 88% of 6-month-old little girls have larger heads, then there is less concern because her head is growing at a steady pace. However, if your daughter's head circumference is slowing in growth, fro example dropping from the 50th percentile down to the 12th percentile, then it is more of a matter for concern because head growth reflects the growth rate of the brain it encloses. On the other hand, if her parents have small heads, then her smaller head size may well be simply hereditary. Your hat size and that of her father would give you an idea if you each tend to be small in head size or not.

Good doctors are alert for growth problems because they know that the brain growth spurt occurs from before birth through the second year of life and it is marked by steady brain growth  without any slowing down. In fact, the baby's skull bones normally do not fuse together until after 10 years of age in order to allow for rapid brain growth without restriction. Sometimes a slowing in the rate of head growth, again assuming that everything has been measured accurately, suggests that some of the skull bones have fused too soon and they might then restrict brain growth. A CT scan will identify this problem. A neurosurgeon can then release the early fusion. This is done best as early as possible, so your baby's doctor is doing the best thing by rechecking in a month's time and making a decision about moving forward with testing. Fortunately CT scans are not painful and they are very quick now compared to even several years ago.

Early fusion is called "craniosynostosis". Its occurrence is fairly common and influenced by many factors including heredity as well as things we do not yet even recognize as contributors to the problem. With early identification and treatment, healthy babies do just fine without any problems in later learning and development.

I hope this information helps and that all is well with your baby.

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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