An observational study to determine the predictive ability of calf circumference and mid-arm circumference for low birthweight in a tertiary care hospital in India

Objectives: The objective was to study the correlation and predictive ability of calf circumference (CC) and mid-arm circumference (MAC) for low birthweight (LBW) babies, i.e., weight <2500 g. Methods: The observational cross-sectional study was done from 1 March 2021 to 31 August 2022 which included inborn babies whose weights were >1000 g within 48 h of life. MAC and CC were determined and receiver operating characteristic curves were plotted for determining the cut-offs to predict LBW. P < 0.05 was considered statistically significant. Results: Amongst 884 live-born neonates included in the study (birthweight >1000 g), 159 (18%) were LBW. The mean birthweight, CC and MAC were 2920.12 ± 503.48 g, 11.39 ± 1.26 cm and 10.41 ± 1.02 cm, respectively. There was a strong positive correlation between CC (cm) and birthweight (g) (rho = 0.88, P < 0.001), MAC (cm) and birthweight (g) (rho = 0.89, P < 0.001) and between MAC (cm) and CC (cm) (rho = 0.86, P < 0.001). At a cut-off of ≤10.2 cm, CC predicted LBW with a sensitivity of 99% and a specificity of 97%. At a cut-off of ≤9.4 cm, MAC predicted LBW with a sensitivity of 98% and a specificity of 97%. Conclusion: The best-suggested cut-off for diagnosing LBW in the present study for CC and MAC was 10.2 cm and 9.4 cm, respectively. Amongst the two parameters, CC was found to be a better predictor with a sensitivity of 99% and a specificity of 97%.