Ultrasonographic Measurement of Anterior Fontanelle Size in Infants with Deformational Plagiocephaly.

: We aimed to investigate the relationship between deformational plagiocephaly (DP) severity and anterior fontanelle size and to explore the connection between fontanelle size and developmental delay. : We enrolled 189 (122 boys and 67 girls; mean corrected age, 119.79 days) of the 256 infants who visited our clinic for plagiocephaly between March 2022 and June 2023. This study analyzed the correlation between cranial vault asymmetry (CVA) and anterior fontanelle size as measured using skull anteroposterior (AP) radiography and ultrasonography. The severity of DP was graded from minimal to severe based on the Argenta classification. Infants were grouped according to CVA severity as follows: Group 1 (CVA ≤ 5 mm), Group 2 (5 mm < CVA < 10 mm), and Group 3 (CVA ≥ 10 mm). Additionally, 40 infants underwent the Denver Developmental Screening Test II (DDST-II) for neurodevelopmental delays and were divided into groups based on the presence or absence of developmental delays for fontanelle size comparison. : Age showed a significant negative correlation with fontanelle size (correlation coefficient -0.234, < 0.05), indicating that fontanelle size decreases as infants age. No significant differences in fontanelle size were observed among the three CVA groups ( = 0.074) or between the developmentally delayed and non-delayed groups ( = 0.09). This study found no correlation between CVA and fontanelle size or between fontanelle size and developmental delay. : The findings show that, while anterior fontanelle size decreased with age, there was no significant correlation between the fontanelle size and the severity of deformational plagiocephaly or developmental delays.