Background: Accurate dosing of medications and fluids during neonatal resuscitations may be critical to prevent neonatal morbidity and mortality. Currently, providers estimate birth weight (Bwt) visually in the absence of accurate Bwt measurement in emergent situations in the delivery room (DR). These visual weight estimates (VWEs) may be imprecise and can lead to dosing errors. We have identified an objective method of estimating Bwt that involves extrapolating prenatal ultrasound estimated fetal weight (UEFW) percentiles onto the modified Fenton growth curve (MFGC).
Objectives: To evaluate the reliability of the VWEs in predicting Bwt, and to compare VWE accuracy to UEFW percentiles extrapolated onto the MFGC. We hypothesize that VWEs are unreliable for predicting Bwt and are less accurate than UEFW percentiles extrapolated on the MFGC.
Methods: This prospective study enrolled appropriate for gestational age (AGA) neonates ≤36 weeks without intrauterine growth restriction or congenital anomalies and whose UEFW percentiles were documented in the EMR. We compared VWEs by attending neonatologists, nurse practitioners (NP) and neonatology fellows in the DR and UEFW percentiles extrapolated on the MFGC curve to actual Bwt. To detect >10% difference between the estimated weights and actual weights with an estimated error of 5%, 65 subjects were needed.
Results: Sixty-five neonates with gestational ages of 24-35 weeks and actual weights of 530-2920g were enrolled. UEFW percentiles extrapolated on the MFGC were more accurate than the VWEs with a smaller absolute mean deviation (p=0.001) when compared to the actual Bwt; however, neither the UEFW percentiles extrapolated on the MFGC nor the VWEs differed significantly from actual Bwt (p=0.78 and p=0.72, respectively). Neonatology fellows exhibited larger absolute deviations between VWEs and the actual Bwt when compared to the NP or the attending neonatologist estimates (p<0.03). Deviation of UEFW percentile on MFGC extrapolations did not correlate with gestational age (p=0.31), race (p=0.57), or sex (p=0.64).
Conclusion: UEFW percentile extrapolation onto the MFGC is a more accurate and therefore more reliable method of Bwt estimation during emergent delivery room resuscitation when compared to VWEs from experienced personnel.
