Background: Previous studies have demonstrated a positive correlation between foot length (FL) and birth body weight (BBW), birth body length (BBL), and head circumference (HC). However, there is no data on birth FL in Taiwan. The aim of this study was to evaluate FL measurement in Taiwanese neonates as a method of estimating other anthropometric indices.
Methods: In this retrospective study, we enrolled 256 babies born at our hospital and Kaohsiung Veterans General Hospital from 2003-2005. Medical records were reviewed for sex, BBW, BBL, HC, gestational age, and birth FL. Ill newborns, small-for-gestational-age babies, or those with poor birth footprints were excluded. FL at birth was measured from the center of the back of the heel to the tip of the big toe. Linear regression analysis was used to investigate the relation of FL to BBW and BBL. The intraclass correlation coefficient was used to assess inter-rater reliability.
Results: A total of 256 babies were reviewed. There were 136 male and 120 female neonates. The gestational age was 38.5+/-1.3 (mean+/-standard deviation) weeks, ranging from 35-42 weeks. The BBW was 3137+/-396g. The BBL was 51.1+/-2.1 cm. The HC was 33.5+/-1.7 cm. The FL was 7.4+/-0.46 cm. The regression equation for BBW (y) on FL (x) was as follows: y=486.2+360.4x (p<0.001, r=0.421). The regression equation for BBL (y) on FL (x) was as follows: y=40.1+1.45x (p<0.001, r= 0.305). The regression equation for HC (y) on FL (x) was as follows: y=14.8+2.53x (p<0.001, r=0.423). FL showed excellent reliability, with an intraclass correlation coefficient of 0.965 (p<0.001).
Conclusion: Our study demonstrated a significant degree of correlation between FL and BBW, BBL and HC. However, it did not reliably estimate BBW, BBL, or HC-the three anthropometric indices were weakly correlated (r<0.5) with FL.