A small fontanel may be caused by microcephaly or premature closure of the skull. A small fontanel may affect the normal growth and development of the baby’s brain, or it may be a physiological phenomenon. The fontanel is generally the space formed by the connection of the two frontal and parietal bones, which is the soft, sometimes throbbing area at the top of the baby’s head that we can usually see. A small fontanel may indicate that the infant has a cranial deformity, and the head circumference should be measured regularly to observe whether the development of the infant’s head circumference is normal before the full moon. If the infant’s fontanel is only small, and the head circumference is within the normal range, it will not usually affect the normal development of the brain. If the fontanel is too small and the head circumference is small, microcephaly should be excluded. Parents are advised to take their infants to the pediatrician for further examination and close monitoring thereafter.