Comparative evaluation of calf, thigh and arm circumferences in detecting low birth weight infants--Part II.

In an earlier study usefulness and validity of calf circumference in the identification of low birth weight (LBW) infants was reported. To evolve a simple indicator in identifying LBW in community, comparative evaluation of three simple measurements, i.e., circumferences of calf (CC), thigh (TC) and arm (AC) was done with respect to their sensitivity and specificity. Though all the three measurements showed a high degree of correlation with the birth weight, calf circumference tended to be most sensitive in identifying almost 95% of LBW infants. Having established the superiority of CC, a two color tape demarcating LBW zone from normal birth weight using 10 cm CC as cut off point was tested by two independent investigators and two ANMs. It was observed that only 5% of cases were misclassified either as LBW or normal weight by the tape with hardly any inter individual variation. Measurement of calf circumference being simple and easy even in the hands of paramedics, it would be used as indicator of LBW and neonatal mortality in the community.

Usefulness of calf circumference as a measure for screening low birth weight infants.

Usefulness of calf circumference (CC) for screening low birth weight (LBW) was assessed in comparison with other anthropometric measurements, crown heel and crown rump lengths (CHL, CRL), Chest (Ch C), head (HC) and arm (AC) circumferences in 256 infants within 24 hours of birth. Calf circumference showed highest degree of correlation (r = 0.83) with birth weight followed by arm and chest circumference and crown heel length. Step down multiple linear regression analysis of birth weight showed highest R2 value with combination of calf, arm and crown heel length (82.1%). Addition of other measurements did not improve the predictive value of the model. Sensitivity of these parameters in screening LBW infants (less than 2500 g) showed 95.7% critical limit for calf followed by 82.6% with arm circumference and 72.5% with crown heel length. False positive responses were similar (18-20%) with all the three parameters. Calf circumference being highly sensitive and easy to measure, is useful in screening most of the low birth weight infants in the communities where weighing scales are not available or cannot be used by peripheral workers.