Fontanelles, often called “soft spots,” are spaces between a newborn’s skull bones that have not yet fully fused. These flexible areas serve a dual purpose: they allow the baby’s head to mold during birth and accommodate rapid brain growth in the first year. Typically, a baby’s fontanelles should feel soft and flat, sometimes showing a slight pulsation due to underlying blood flow. A normal fontanelle will not appear noticeably sunken or bulging.
Identifying a Sunken Fontanelle
A sunken fontanelle appears as a noticeable indentation or dip in the soft spot on a baby’s head, resembling a concave shape. While a slight inward curve can be normal, a significantly sunken appearance suggests a potential issue. The anterior fontanelle, the larger, diamond-shaped soft spot on the top of the head, is the most commonly observed site.
To confirm, gently touch the fontanelle. It should feel firm but yield slightly inward, not rigid or deeply depressed. If the soft spot is visibly dipping inward, resembling a dent on the skull, it indicates a sunken fontanelle. This differs from temporary slight bulging that can occur when a baby cries, vomits, or lies down, as a normal fontanelle returns to a flat state once the baby is calm and upright.
Common Causes and Accompanying Signs
The most common reason a baby’s fontanelle appears sunken is dehydration, which occurs when the body loses more fluid than it takes in. Infants can become dehydrated from prolonged vomiting or diarrhea, insufficient fluid intake, or a fever. Excessive sweating can also lead to fluid loss.
When a baby is dehydrated, other symptoms often accompany a sunken fontanelle. These include fewer wet diapers, indicating decreased urine output. The baby’s mouth and lips may appear dry, and they might produce few or no tears when crying. A dehydrated infant may also exhibit lethargy, unusual sleepiness, or increased irritability. Their skin might feel dry and cool, and in more severe cases, they might have a rapid heart rate or breathing.
When to Seek Medical Care
A noticeably sunken fontanelle, especially when accompanied by other signs of dehydration, warrants immediate medical attention. This is a medical emergency and should not be managed at home. Contact a pediatrician or seek emergency care right away.
When speaking with medical professionals, provide as much detail as possible about the baby’s recent health. This includes when the sunken fontanelle was first noticed, its severity, and any recent illness, vomiting, diarrhea, or excessive sweating. Mentioning the baby’s fluid intake, current alertness, and other symptoms like dry eyes or mouth will aid diagnosis and treatment.