[Comparison between two growth curves for small for gestational age diagnosis]

It was to compare the use of two growth curves for the diagnosis of small-for-gestational-age (SGA) infants, having the 10th percentile as reference.

In a retrospective study, data of 20,567 singleton live births from January 2003 to June 2014 were analyzed, and divided according to gestational age: (a) 23 to 26, (b) 26 to 29, (c) 29 to 32, (d) 32 to 35, (e) 35 to 38, (f) 38 to 41 and (g) >41 weeks. Data were paired and analyzed using the McNemar test, with the level of significance set at 0.05.

The curve designed by Alexander indicated a higher percentage of diagnosis of SGA than the curve constructed by Fenton for every category of gestational age up to 41 weeks, more markedly in the 32-35 week group (18.5%). Between 37 and 40 weeks of gestational age, Alexander's curve exceeded Fenton's curve in 9.1% of the cases in the diagnosis of SGA.

The Fenton curve provides a more accurate evaluation of an infant's growth since it is gender-specific and allows measurement of three parameters. It has also been constructed with newer data and more sophisticated statistical tools.