Early closure of fontanel does not necessarily affect the baby’s IQ. If the diameter of the baby’s head is in the normal range, early closure of fontanel will not affect the IQ. Generally speaking, a baby’s fontanel closes at the age of 1.5 years to 2 years, and the posterior fontanel closes at three months after birth. As babies grow and develop differently, the fontanel closure time is not exactly the same. If a baby’s fontanel closes early but his head circumference is similar to that of his peers, it is unlikely to affect his intelligence. However, if your baby’s head circumference is significantly smaller than that of his or her peers, you need to be alert to the possibility of microcephaly. In severe cases, the baby’s intellectual development may be affected. Parents are advised to bring their babies to the child health department of the hospital for regular measurements of head circumference and other data, and if necessary, to improve the relevant examinations under the guidance of the doctor to determine whether it is a normal level.