The soft spot on a baby’s head is called a fontanelle (also spelled fontanel). Newborns actually have two fontanelles: a larger one toward the front of the head and a smaller one at the back. These gaps between the skull bones are completely normal and serve important purposes during birth and early brain development.
Where the Two Fontanelles Are Located
The anterior fontanelle is the one most parents notice. It sits on top of the head, just forward of center, at the junction where four skull bones meet. It has a diamond (rhomboid) shape and is typically the larger of the two. This is what people usually mean when they refer to “the soft spot.”
The posterior fontanelle is smaller, triangular, and located at the back of the head where the skull bones meet near the base of the crown. It’s less noticeable and closes much earlier, so many parents never realize it’s there.
Why Babies Have Soft Spots
A baby’s skull isn’t one solid piece of bone. It’s made up of several separate plates connected by flexible seams called sutures. The fontanelles are the wider gaps where multiple sutures meet. This design allows the skull plates to overlap slightly during delivery, helping the baby’s head fit through the birth canal. That’s why many newborns have a slightly elongated head shape right after birth.
After birth, the fontanelles continue to serve a purpose. A baby’s brain grows rapidly in the first two years of life, roughly tripling in size. The flexible gaps give the skull room to expand alongside that growth. As the brain reaches a more stable size, the skull bones gradually fuse together and the soft spots disappear.
When Fontanelles Close
The posterior fontanelle (at the back) closes first, typically by 6 to 8 weeks of life and almost always by 3 months. The anterior fontanelle (on top) stays open much longer, generally closing between 12 and 18 months of age, though the exact timing varies from one child to another. Pediatricians check fontanelle size at routine visits and may measure them to track whether closure is happening on a normal timeline. A fontanelle that closes unusually early or stays open unusually late can signal a growth issue worth investigating.
Is It Safe to Touch the Soft Spot?
Yes. Despite how vulnerable it looks, the fontanelle is covered by a thick, tough membrane that protects the brain underneath. Normal handling, washing, brushing hair over it, and gentle touching pose no danger at all. You don’t need to avoid the area during bath time or treat it as fragile during everyday care.
What the Soft Spot Can Tell You
The fontanelle acts as a small window into your baby’s health. In a healthy, well-hydrated baby, the soft spot feels flat or very slightly concave and may pulse gently, which is normal.
Sunken Fontanelle
A noticeably sunken soft spot is one of the key signs of dehydration in infants. Other signs that often appear alongside it include sunken eyes, few or no tears when crying, fewer wet diapers than usual, and unusual drowsiness or irritability. A visibly sunken fontanelle needs prompt medical attention, as it can indicate serious dehydration.
Bulging Fontanelle
A tense or bulging fontanelle can indicate increased pressure inside the skull. This happens when fluid builds up in the brain or when the brain swells, potentially from conditions like meningitis (infection of the membranes around the brain), encephalitis (swelling of the brain tissue itself), or hydrocephalus (a buildup of fluid inside the skull). A truly bulging fontanelle, especially combined with fever or excessive sleepiness, is a medical emergency.
It’s worth noting that brief, temporary bulging can happen when a baby cries hard or strains. The concern is a fontanelle that remains tense or raised when the baby is calm and upright.