An Easy and Accurate Method of Estimating Newborn Birthweight for Resuscitation

ABSTRACT

Emergency administration of medication based on birthweight is often required in newborn resuscitation. Actual weighing is often delayed because of the emergency situation. Therefore drugs are given according to weight estimates by physicians or nurses. The purposes of this study were to develop a measuring tape using the infant's length and head circumference to determine body weight and to evaluate the performance of the tape measurements to staffs' estimates. Weight, length, and head occipito-frontal circumference (OFC) measurements of 200 newborn infants were collected. By regression analyses, the best log curve for both length and OFC versus weight was determined. From these data, a measuring tape was constructed with the corresponding weights marked for both length and OFC. Forty-five newborn infants with gestational ages of 26 to 40 weeks were studied. Prior to actual weighing, estimates of the birth-weights were obtained and recorded from the tape measurements using both the length and OFC and staffs' estimates. For infants less than 2 kg, the average percent error was less by the tape length (1.2%) and OFC (0.7%) compared with staffs' estimates (-7.2%). The tape was also useful in estimating weights of small for gestational age infants. The tape OFC (7.8% error) was more accurate than staffs' estimates (26% error) in these growth-retarded infants. The clinical precision of the tape was 3% with an intrameasurer variability of 5%. We conclude that estimating the birthweight in infants using our tape method is a practical and more accurate way than staff estimates, especially for low birthweight and small for gestational age infants.