Should I worry about my infants small head size?

All families worry about whether their babies are developing “normally”. Concern is often more heightened when a baby’s head is on the small size. Here are two questions I received recently on this topic. As you’ll see, appearances can be deceiving and more times than not there is no reason for alarm:

Question #1
Dear Dr. Gwenn:

I had my son two weeks early due to IUG. We had an ultra sound at 38 weeks and his head measurement was not what they expected so I had a c section immediately. He was 5lbs 13 oz. and 19.5 inches long. He has grown on a normal curve but his head circumference has been just below the curve since he was born. He seems very content and has for the most part developed normally but I am concerned about his head size being too small.

His head at 8 months is about 42 cm. Am I worrying too much? I have read lots on the internet about microcephaly and it just scares me more!


Question #2
Dear Dr. Gwenn:
Yesterday at my two month old baby’s well child exam, his doctor said his weight and length are good but his head size, 15 ¼” is a bit on the low side, in the 25th percentile. It was 14 ½” at his 2 week visit. She didn’t seem worried and said she’d keep an eye on it over time.

I have read that head growth equals brain growth. I am really worried that his brain might not be growing at a normal rate. I feel so bad that maybe we did something. Is there anything we can do to help? Have any of you had the same problem? Will he grow normally, intelligence wise? I don’t want my baby to be picked on. I am so scared that his body might keep growing but his head size might remain the same or very small. Is that likely to happen?

Thank you.

Even though these questions contain many differences, the most important fact they both share: both babies are developing normally and achieving their milestones. That is the best evidence that we have for realizing a baby’s brain is doing exactly what it is supposed to do.

Growth parameters can be difficult to evaluate and can cause alarm if you are not quite sure what to make of them. Growth curves represent the entire population so some kids will fall on the high end, some on the low end, and many in the middle. What we look for is the pattern over time and not just the isolated percentage. Also important is prenatal history and birth history. Many babies are born with IUGR and catch up nicely over time. CW, if you plot your baby’s head circumference from birth you may see that it is increasing along its own curve but since it started below it is just tracking there.

While we do worry about outliers, kids falling below or above the curves, we don’t worry so much about kids who are at the lower percentiles but grow along that curve. The Head Circumference Chart can be very helpful because we can see that a baby’s growth is progressing at whatever line it should be one.

Your baby will tell us his brain is developing normally by meeting his developmental milestones. Check out our Infant Development page for more information about what your baby should be doing today and what to expect in the coming months. As long as he is on track developmentally, you need not worry. One of the advantages of the frequent infant well child visits is to catch infants early who may need some early intervention and help with milestones. If you have any concerns about this, you should discuss it with your pediatrician. If she is not worried, you need not be worried.

Finally, as in these questions, parents often worry that they “did something” to cause this. If you took care of yourself during your pregnancy and had regular care, you did your job. All you can do now is love and nurture your son. That above all is what determines later success in life. Intelligence has a great deal to do not only with nurturing when young but genetics. All any of us can do is accept our kids for whatever learners they end up being and help them be the best they can be. Both these babies will look just like all the other kids when he is in school!

I would encourage both these families to talk to their pediatricians who know the facts of the pregnancy and the baby’s development better to get more reassurance. Both cases are different but the statistics are on the side of good outcome for both kids.