[The problems that arise when making and using an intra-uterine growth curve (author's transl)].

The author analyses the different intra-uterine growth curves that are described in the literature and shows how in use as reference norms they have a restricted value. The author draws attention to the fact that no other author cited in the literature has used an objective method to control the gestational age of the fetus when making curves. The author demonstrates that in 17.3 p. 100 of cases the gestational age has to be corrected when making his own growth curve and this is done by measuring the bi-parietal diameter early in the pregnancy. He studies the repercussions of this high figure of non-correspondence with the dates at different levels of the curve and the percentage of infants defined as hypotrophic, macrosomic or post-mature.