[The fetal development curves of newborn infants in the Hospital de Cruces (Vizcaya). I. Weight].

Taking a 33,753 live birth sample, without congenital or genetical malformations and from single pregnancies, delivered at Cruces Hospital (Vizcaya) from January 1st. 1987 to December 31st. 1992. Fetal growth curves of weight, have been developed. For every gestational week, percentile distribution, mean and standard deviation and 95% confidence interval of the mean have been calculated. The later calculation allowed us to compare our means with those of national and international studies, finding significance differences with the great majority of them. Since the sample used was of large size, we believe that the resulting norms adjusted to our population. Being useful clinical, public health and investigational purposes.