Learning Objective #1: The learner will be able to understand the geometric assumption to serve the evidence-basis for body surface area (BSA) estimation in newborns.

Learning Objective #2: The learner will be able to apply the suitable BSA formula to pediatric population including newborns.

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Purpose: Body surface area (BSA) is an important biometrics for drug metabolism, body water composition and regulation, and thermoregulation in infants. However, most BSA equations were developed decades ago with little appreciation for the biometric characteristics of infants. The study was conducted explicitly to explore the suitability of using existing formulas to estimate the BSA of newborns when direct measurement is not practical.

Method: In 589 full term newborns of normal weight and height, the five BSA estimations (in cm2) were performed using four known formulas by Boyd (BSA-Boyd), by Meban (BSA-Meban), by Mosteller (BSA-Mosteller), and by Dubois (BSA-Dubois), and the arithmetic mean of these four formulas (BSA-Mean).

Results: BSA-Meban was most similar to the BSA-Mean with a mathematically perfect correlation and the least dissimilarity using Euclidean distance (ED), followed by BSA-Mosteller. Both BSA-Boyd and BSA-Dubois show about a 5% deviation above and below the BSA-Mean, respectively, with a consistent dissimilarity using ED regardless of the same goodness of fit. The degree of deviation significantly increased with the weight and significantly decreased with height.

Conclusions: The study concluded that the BSA formula by Meban is possibly the best estimate of BSA for newborns among the existing formulas available today, followed by the formula of Mosteller. Due to either overestimation or underestimation of BSA, two formulas (BSA-Boyd and BSA-Dubois) are not recommended for BSA estimation of newborns. A nomogram for BSA estimation is urgently needed for pediatric use especially with increasing preterm birth and obesity in modern society.