Prognostic performance of several anthropometric indicators for predicting low and insufficient birth weight

Weight gain and several anthropometric indicators were studied in a sample of 181 pregnant women. The period considered ranged from the 12th to the 34th weeks of gestation. Changes in all of the attributes were calculated and related to a birth weight below 3,000 g. Optimal cut-off points for each indicator were defined as those which minimize a loss functioin which depends on the rates of false positive and false negatives. The independent predictive capacity of each attribute was assessed by means of sensitivity, specificity, positive and negative predictive values, relative risk, and two "measures of detectability" associated to the ROC (relative operating characteristic) curve of the attribute. A logistic regression model was fitted by searching for the best combination of indicators. The individual predictive capacities of the attributes were considerably improved when they were combined into a logistic equation. © 1995 Wiley-Liss, Inc.