Objective: to evaluate the evolution of estimated fetal weight in normal pregnancies in Campinas, Brazil, between 20 to 42 weeks.
Design and methods: A descriptive study was performed, including 2,874 normal pregnant women studied through routine obstetric ultrasound with fetal biometry, using the Hadlock (1991) formula for fetal weight estimation. Data were evaluated by fitting a curve with the 10th, 50th, and 90th percentiles of fetal weight for gestational age, subsequently submitted to a smoothing procedure by quadratic polynomial adjustment.
Results: the 50th percentile was 368g at 20th week, 1,512g at 30th, and 3,417g at 42nd week. There was a mean weight increase of 200g per week from the 27th to 38th week, when the gain decreased.
Conclusions: The availability of a Brazilian curve of normal estimated fetal weight will allow for prenatal ultrasound diagnosis of deviations.