Anterior fontanel size in term and late preterm Hispanic neonates: description of normative values and an alternative measurement method.

We sought to determine anterior fontanel size (AFS) in Hispanic neonates and to compare two methods of measurement. The traditional method (TRAD) was defined as the sum of the longitudinal and transverse dimensions, divided by 2. Diagonal measurements (DIAG) were obtained between the estimated midpoints of the edges of the frontal and parietal bones, and the sum was divided by 2. Interobserver reliability was assessed in a subset of the study population. One hundred seventy neonates with gestational age 38.9 +/- 1.5 weeks were studied at a median age of 32 hours. Measurements by TRAD and DIAG (mean +/- standard deviation) were 22.5 +/- 7.9 mm and 20.9 +/- 6.7 mm, respectively ( P = 0.12). AFS was greater in males and in neonates whose mothers had longer duration of labor. Interobserver reliability was excellent for both methods. This study provides normative data for AFS using two methods in Hispanic neonates. A modest trend toward less variability with the DIAG method was noted. Male gender and longer duration of labor were associated with larger AFS.