Prediction of low birth weight from other anthropometric parameters in Nnewi, south eastern Nigeria

Abstract

Background: Low birth weight is a global problem but presents a major burden on the neonatal services in developing countries such as Nigeria, and brings to bear a greater strain on the meagre resources available for health care delivery and family financing. In a resourceconstrained setting as ours, proper weighing of all newborn infants and medical surveillance of low birth weight infants, although highly desirable, are often not achieved due to unavailability of suitable, functional weighing scales. There are serial cut-off points for the various anthropometric indices for the normal birth weight babies below which any baby is termed low birth weight. This study assessed the predictive values of anthropometric measurements in the detection of low birth weight newborn babies and also determined the local specific cut-off points for these measurements in Nnewi, Southeast Nigeria.
Methods: This was a crosssectional study in which length, occipitofrontal circumference, mid-arm circumference and maximum thigh circumference of 428 singleton babies were ascertained within 24 hours of delivery. Data were analysed using the Statistical Package for Social Sciences (SPSS) software. Correlation and linear regression analyses were done to examine the linear relationship between the predictors and birth weight. The sensitivity, specificity and predictive values were calculated at serial cut–off points and the points of best discrimination determined.
Results: The low birth weight prevalence was 15.2%. Maximum thigh circumference attained the highest correlation with birth weight (r = 0.904), greatest coefficient of determination (r2=0.817), and least measure of dispersion around the actual birth weight. Thus maximum thigh circumference, which has a cut-off point of 16.75cm, was the best predictor of low birth weight, with 98.5% sensitivity, 92.3% specificity and diagnostic accuracy of 93.2% (P<0.001).
Conclusion: Routine measurements of maximum thigh circumference in resource-poor countries is an effective proxy for weight at birth in prenatal assessments and epidemiologic surveys.

Key words: anthropometric parameters,low birth weight, newborn, Nigeria