Newborn head molding is an abnormal head shape that results from pressure on the baby's head during childbirth.
Newborn cranial deformation; Molding of the newborn's head
The bones of a newborn baby's skull are soft and flexible, with gaps between the plates of bone.
The spaces between the bony plates of the skull are called cranial sutures. The front (anterior) and back (posterior) fontanelles are two gaps that are particularly large. These are the soft spots you can feel when you touch the top of your baby's head.
When a baby is born in a head-first position, pressure on the head in the birth canal may mold the head into an oblong shape. These spaces between the bones allow the baby's head to change shape. Depending on the amount and length of pressure, the skull bones may even overlap.
These spaces also allow the brain to grow inside the skull bones. They will close as the brain reaches its full size.
Fluid may also collect in the baby's scalp (caput succedaneum), or blood may collect beneath the scalp (cephalohematoma). This may further distort the shape and appearance of the baby's head. Fluid and blood collection in and around the scalp is common during delivery. It will most often go away in a few days.
If your baby is born breech (buttocks or feet first) or by Cesarean section, the head is most often round. Very severe abnormalities in head size are NOT related to molding.
Smith JB. Initial evaluation: history and physical examination of the newborn. In: Gleason CA, Devaskar SU. Avery's Diseases of the Newborn. 9th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 25.
Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.