We carried out a prospective study at Ouagadougou, from March 1 1997 to April 30 1998, in which we plotted curves of fetal weight gain, estimated by ultrasound biometry, with the aim of comparing our results to those of other authors and establishing a local chart. We established a growth curve from 936 fetal weights estimated during the follow up of 126 pregnant women. The mean age of the women included was 26 +/- 0,8 years and 52.4% were of the mean socioeconomic level. We identified significant differences between our weight gain curve and those of other authors. The factors involved in this difference are unclear but may be nutritive, ecological and ethnic in nature. Further work is required to produce local charts, to optimize the estimation of fetal weight.