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 anterior and 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.
During a head-first delivery, pressure on the head caused by the narrow birth canal (vagina and pelvic bones) may mold the head into an oblong shape. These gaps or spaces allow the baby's head to change shape. Depending on the amount and length of pressure, the skull bones may even overlap.
These gaps or 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 usually disappears after a few days.
If your baby is born breech (buttocks or feet first) or by cesarean section, the head is usually round and otherwise well-shaped. Extreme abnormalities in head size are NOT related to molding.
Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.