What Are They And Why Are They There
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What are "soft spots" on a newborn's head and do they need any special care? - Linda in Lexington, Kentucky
The Physician Answers:
The "soft spots" - or in medical lingo the "fontanels" - are openings in the skull where the head bones have not quite yet closed at two locations. The larger fontanel is at the top of the newborn's head - it's about two inches wide and is diamond-shaped. This soft spot is officially called the anterior fontanel and closes by the time the baby is 18 months old. The posterior fontanel is about one-half inch in diameter and is also diamond-shaped, but it is much harder to find because it's at the back of the head. This fontanel closes completely by the third month.
The fontanels serve two major purposes and an unofficial one which is my favorite. The major purposes are to allow the fetal skull to have some ability to shift and compress while passing through the birth canal. The second purpose of the fontanels is to allow for the rapid, extreme growth of the brain in the first year of life, which is why the anterior fontanel doesn't close until about 18 months. My favorite use of the fontanels as a physician, is that it is a readily available area to reference when determining if a baby is dehydrated. Normally, the membrane covering the fontanels is flat, or maybe bulging outward when crying,sneezing or having a bowel movement. However, when the baby is dehydrated, this membrane becomes depressed. This may be due to illness or poor feeding... in either case call the baby's doctor.
Lastly, you asked if they need any special care and my answer is that you should provide just a moderate amount of protection from being poked. This is difficult to achieve with older toddler-aged siblings (like I have), but do the best you can. You can wash and dry that area during a shampoo, just use more care than needed at the harder, closed parts of the skull. Before you know it these soft areas will be closed just in time for all the toddler tumbles.
Dr Jane Forester