Role of foot length in predicting the gestational age of a neonate

The aim was to study neonatal foot length as a simple method for quick gestational age assessment, which can be done by basic health care personnel, overcoming the technicality required by other assessment methods.

A Prospective descriptive study was done. Live-born neonates at Saveetha Medical College and Hospital, Chennai, were enrolled. Gestational age was assessed by New Ballard's Scoring (NBS), and foot length (FL) was measured using the paddle blades of automated digital Vernier callipers within 24 hours, while birth weight was taken within 72 hours of birth. Based on gestational age, babies were grouped into preterm, term and post term and were sub-classified as small for gestational age (SGA), appropriate for gestational age (AGA) and large for gestational age (LGA) based on Lubchenco's intrauterine growth chart. Correlation and regression analysis with a Scatterplot was done.

Out of 150 neonates, term, preterm and post-term were70.3%,28.4%and1.3% while SGA, AGA, and LGA babies were11%, 85% and 4%. respectively. Mean foot length was7.588±0.57. With a range of 5.2-8.4cm. Foot length strongly correlated with gestational age in Preterm AGA, preterm SGA and Term AGA babies (<0.05). The correlation coefficient between foot length and gestational age was higher in preterm babies (R2=0.56) and SGA babies (R2=0.66). Gestational age in 53% of the total study population could be predicted with a regression equation.

Foot length may be useful for quick estimation of gestational age in preterm and term neonates for early referral of newborns requiring special care, and can even be done by basic healthcare personnel.