Pediatrician Clay Jones posts an excellent primer on the lumpy, bumpy shapes of newborn babies’ heads:

Pediatricians, particularly those who spend a significant amount of time caring for newborns, see a lot of babies with unusually-shaped heads. Although to be fair, the fact that the overwhelming majority of vaginally-delivered babies, and quite a few born via Caesarean section, will have a transient and abnormal shape to their heads makes it, well, not unusual. In fact, I rarely make it out of the room without some discussion and reassurance regarding the lumps and bumps of a new arrival’s head.



Molding of the five flexible bony plates of the skull occurs as a baby’s head presses on the thinning and dilating cervix during labor and then slowly passes through the birth canal during delivery. This allows safe passage through such a narrow opening and prevents damage to the newborn’s brain, leading to the classic, but transient (it resolves in a day or two), “cone-head” appearance of the skull. Edema (swelling) over areas of the skull is common and also short-lived. Collections of blood can get trapped under the lining of the bone, causing impressive swellings called cephalohematomas. These usually harmless lumps harden and calcify as they slowly shrink over weeks-to-months. Finally, heads of newborns can be misshapen merely due to the position of the fetus in relation to the uterine wall, or in relation to a twin, during pregnancy. These typically resolve quickly.

Now that the AAP recommends that babies be put to sleep supine (on their backs, instead of their sides or prone on their stomachs), we see a lot of flattening deformities of the skull in young babies called positional plagiocephaly. Flattening is more likely to occur on one side of the back occipital bone, usually on the side the baby prefers facing during sleep. It is also more likely to occur if a baby has torticollis — a tightness in one of the neck muscles which prevents easy head turning from side-to-side. These deformities are readily apparent to parents, are usually mild, and stop progressing after 3-4 months of age, before slowly resolving over a year or more. As long as these flattened areas in the back of the skull don’t show corresponding asymmetry of the forehead or the face, repositioning of the head during sleep, reassurance and continued observation is the preferred approach to treatment. If the flattening becomes severe and facial asymmetry is noted, then babies can be fitted with a helmet to be worn 24/7 for a few months to prevent further plagiocephaly. Torticollis, when present, is treated with neck-stretching exercises taught to parents by a physical therapist.

Eventually, these “tectonic plates” of the skull will fuse along suture lines, the soft spots will close, and the older infant and toddler’s head will assume its typical shape. However, if one or more of these plates fuse too early, the skull will not grow properly and symmetrically, leading to craniosynostosis:

For example, in the case of sagittal suture fusion the head tends to become strikingly long and narrow, a shape known as scaphocephaly. This translates to “boat skull.” When the coronal suture is fused prematurely on both sides of the forehead, the resulting shape is known as brachycephaly or “short skull.” The skull will be shortened from front to back but abnormally wide, and if untreated will begin to preferentially grow upward as well. So depending on which sutures are fused before their time, and if the fusion occurs on one or both sides of the head, there are a variety of recognized pathognomonic shapes ranging from mild to extreme.


If craniosynostosis is suspected, evaluation with a CT scan and a visit with a pediatric neurosurgeon or craniofacial specialist precedes surgical (and not, Jones emphatically states, chiropractic) correction and a cosmetically normal outcome.