OBJECTIVETo study the development of anterior fontanel(AF) in children less than 2 years of age.

METHODThe size of AF of the children under 2 years of age was measured. The criteria were: (1) All the children were singletons and term (37 weeks ≤ gestational age ≤ 40 weeks) at birth, birth weight > 2500 g. (3) Those with intracranial diseases (included trauma and asphyxia) and scalp hematoma were ruled out. (3) Healthy children (without intracranial disease, growth retardation, congenital syndrome or bone metabolic diseases such as rickets).

RESULT(1) The mean value of AF in neonates was 1.5 (0.3 - 2.5) cm, and the average of the AF at 1 month after birth was 2.2 cm, which was the largest one. The size of AF was 1.0 (0.3 - 2.0) cm at age 12 months, and 0.5 (0.3 - 0.7) cm at 24 months. (2) The percentage for the closure of the AF was 3% at 6 months, 26.5% at 12 months, and 93.0% at 24 months. (3) There were no gender differences in the size of the AF (P > 0.05). And the size of AF was not correlated with the development levels of weight, length, and head circumference (P > 0.05).

CONCLUSION(1) The size of AF at 1 month was maximum (2.2 cm), and then decreased by years. The AF was almost closed (93%) at 24 months. (2) There were no gender differences in anterior fontanel (P > 0.05). The size of AF was not correlated with the growth of weight, length, and head circumferences (P > 0.05). (3) The fontanel dimensions should be represented by oblique diameters of the fontanel in clinical pediatrics. (4) The AF closure time needs to be further evaluated in normal children.