Development of a new fetal growth curve from a large sample of Italian population.

Background: Intrauterine growth curves are considered an essential instrument in prenatal medicine for an appropriate auxological classification of fetuses and they have a great importance in clinical practice. Nowadays, in Italy a national curve published in 1975, is the most used. It Is based on birth weights of 8458 newborns from physiological pregnancies. The aim of the present study was to develop a modern fetal growth curve based on accurately selection of 35 240 physiological singleton Italian pregnancies with sure gestational age confirmed by ultrasound.

Methods: This is a retrospective analysis of 35,240 pregnancies from "A. Gemelli" University Hospital in Rome and "S. Anna" University Hospital in Turin from January 2001 to December 2006. Non-resident pregnant women or coming from other countries, women with diabetes, hypertensive disorders of pregnancy, multiple pregnancies, fetuses with major malformations and/or chromosomal disorders and stillborn fetuses were excluded.

Results: An increasing trend of median neonatal weight, in comparison with the previous Italian National Curve drawn up in 1975, was found.

Conclusions: Combining data from two centers, a new fetal growth curve, in which the 10th and the 90th percentiles are clinically reliable, was performed, in order to have a better tool to evaluate the Italian fetal population. A trend towards an increase of birth weight was observed if compared to previous growth curve drawn up more than 30 years ago.