Local References for Ultrasound-Estimated Fetal Weight Based on 2,211 Singleton Pregnancies in the City of Curitiba, South of Brazil

Objective To develop reference curves of estimated fetal weight for a local population in Curitiba, South of Brazil, and compare them with the curves established for other populations. Methods An observational, cross-sectional, retrospective study was conducted. A reference model for estimated fetal weight was developed using a local sample of 2,211 singleton pregnancies with low risk of growth disorders and well-defined gestational age. This model was compared graphically with the Hadlock and Intergrowth 21st curves. Results Reference curves for estimated fetal weight were developed for a local population. The coefficient of determination was R-2 = 99.11%, indicating that 99.11% of the fetal weight variations were explained by the model. Compared with Hadlock curves, the 50th, 90th, and 97th percentiles in this model were lower, whereas the 10th percentile nearly overlapped, and the 3rd percentile was slightly higher in the proposed model. The percentiles were higher in the proposed model compared with the Intergrowth 21st curves, particularly for the 3rd, 10th, and 50th percentiles. Conclusion We provide a local reference curve for estimated fetal weight. The proposed model was different from other models, and these differences might be due to the use of different populations for model construction.