Use of mid-arm and chest circumferences to predict birth weight in rural north India

Abstract

Study objective - To determine the most appropriate surrogate indicator and its cut off point for identifying low birthweight babies in northern India. Study setting - A secondary level hospital at Ballabgarh. The patients were from nearby rural and urban areas and mostly belonged to lower and middle socioeconomic strata. Participants - These comprised 733 singleton newborns delivered in the hospital between April and December 1991. Design - Birth weight, arm circumference, and chest circumference were measured in all the newborns. Different cut off points for each index were identified and their validity was tested. Based on the regression equations, a simple chart was drawn up and was used to predict weights for different arm and chest circumferences in the hospital and community settings. Main results - Cut off points for arm and chest circumferences of 8.5 cm and 29.5 cm respectively gave a sensitivity and specificity of around 80%. When the chart based on the regression equations was tested in both the hospital and the community, chest circumference was found to be the better of the two indicators. Conclusion - Chest circumference seems to be the most appropriate surrogate measure for birth weight. Cut off points of 29.5 cm and 27.5 cm seem to be satisfactory for predicting birth weight below 2500 g and 1800 g respectively. The birthweight prediction card using chest circumference was effective in predicting birth weight.