A wide fontanelle occurs when the fontanelle is larger in size than expected for the age of the baby. Slow or incomplete ossification of the skull bones is most often the cause of a wide fontanelle.
Review Date 10/2/2019
Updated by: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.