A study of correlation of foot length and new Ballard score in determining the gestational age of newborns

Bijli Pathiyil, Anuradha Varadhan, Balachandar B. Varadhan


Background: Gestational age (GA) estimation plays a vital role in obstetric, perinatal and neonatal care. Foot length (FL) measurement can serve as a simple, easy and cost effective parameter for estimating GA. The aim of this study was to determine correlation between foot length of new born and GA by new Ballard score and forming a percentile chart if a positive correlation was found.

Methods: GA assessment of newborns born in our hospital was done by new Ballard score within 24 hours of life. FL was measured using vernier caliper. Neonates were classified as pre term, term and post term and also grouped as small for GA (SGA), appropriate for GA (AGA) and large for GA (LGA).

Results: FL measurement was strongly correlating with GA assessment by new Ballard score, with overall correlation coefficient r=0.897 (p<0.001). FL increased as GA increased. Strong positive correlation was seen in pre term and term newborns. The cut-off foot lengths for identifying preterm and early preterm neonates were 73.14 mm (diagnostic accuracy 88.4%) and 68.49 mm (diagnostic accuracy 95.3%), respectively.

Conclusions: Strong positive correlation of foot length with GA by new Ballard score was obtained and a percentile chart of foot length for each GA was formed, with mean and standard deviation. This can serve as a simple and quick tool, requiring less expertise for GA assessment.


Newborn, Gestational age, Foot length, New Ballard score, Correlation

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