When a newborn’s head appears slightly elongated or ridged, it is often due to head molding. This occurs when the soft, flexible skull bones momentarily overlap, a finding sometimes called overlapping or overriding sutures. This temporary change is a natural adaptation to the birth process.
Understanding Cranial Sutures and Head Molding
The newborn skull is composed of several bony plates connected by fibrous joints called cranial sutures. These sutures, along with the larger gaps known as fontanelles or “soft spots,” allow the skull to be flexible. This flexibility is necessary to accommodate the pressure of passing through the narrow birth canal and to allow for the rapid growth of the infant’s brain after birth.
Head molding is a direct consequence of pressure exerted during a vaginal delivery. As the baby moves through the birth canal, the skull plates slide and temporarily overlap at the suture lines to reduce the head’s diameter. This overlapping creates the visible ridge on the baby’s head. Babies born via cesarean section often do not experience this molding.
The Typical Timeline for Overlap Resolution
The resolution of this temporary overlapping is typically rapid in healthy newborns. For most infants, the overlapping sutures begin to realign and the ridging subsides within the first two to three days following birth. Removing the pressure immediately after delivery allows the bony plates to gradually return to their normal, edge-to-edge position.
The baby’s brain experiences rapid postnatal growth, which helps expand the skull and alleviate the temporary overlap. In cases of more pronounced molding, such as after a long labor or an instrumental delivery, resolution may take longer, sometimes up to a week or two. The duration of labor and the severity of the initial molding influence the speed of this natural process.
This rapid, temporary resolution is distinct from the permanent closure of the sutures and fontanelles. The posterior fontanelle typically closes within the first two months, while the larger anterior fontanelle may remain open until the child is between 7 and 19 months old. The fibrous sutures remain flexible for many months to years to permit brain expansion. Monitoring head circumference during pediatrician visits ensures that head expansion is occurring appropriately.
Signs That Require Pediatric Consultation
While temporary overlapping sutures are normal, parents should be aware of signs that warrant medical consultation. A ridge that feels fixed, hard, or rigid and persists beyond two to three weeks should be assessed by a pediatrician. This persistent ridging could suggest craniosynostosis, where one or more sutures fuse prematurely.
Craniosynostosis prevents skull growth perpendicular to the fused suture, forcing the head to grow in an abnormal or atypical shape. The resulting head shape is determined by which suture is affected, such as a long and narrow head from premature closure of the sagittal suture. Other signs of concern include an abnormal head shape that persists or worsens, or a failure of the baby’s head circumference to increase appropriately during well-child visits.
A pediatrician will examine the head shape and feel the fontanelles and suture lines to differentiate between benign molding and premature fusion. They will also look for associated symptoms such as irritability, vomiting, or a bulging or sunken fontanelle, which can signal increased intracranial pressure. Positional plagiocephaly, a common cosmetic flattening, can also be distinguished from craniosynostosis by a medical professional.