The accuracy of test weighing for preterm infants.

A series of recent studies has suggested that preterm infants are capable of breast feeding at weights less than 1,500 g. However, estimating intake during breast feeding for these small infants is important for safe clinical practice and valid research. The purpose of this study was to compare the accuracy of test weighing as an estimate of intake for preterm infants using two types of scales: a mechanical scale (Toledo) commonly used in many special care nurseries, and a new electronic scale (SMART; Olympic Medical). Fifty clinically stable preterm infants, weighing between 1,088 and 2,440 g (mean = 1,599 g), who were clothed identically for all weights and feedings, were studied. Two experienced neonatal nurses (RN-1 and RN-2) collected the data. Before feeding, each infant was weighed once on each scale by each nurse; the order of nurse and scale was assigned randomly. Then, RN-1 administered a prescribed volume of feeding. After feeding, RN-2 weighed each infant twice on each scale; the order of scale was assigned randomly. RN-1 was blind to postfeed weights, and RN-2 was blind to actual volume of intake. Results indicated that differences between the actual and estimated volumes of intake were smaller for the electronic than for the mechanical scale on all measures. These findings suggest that test weighing with an electronic scale provides an accurate estimate of intake for preterm infants, and support the use of this instrument in clinical practice and research.