Comparison between two growth curves for small for gestational age diagnosis

Fernanda Pipitone Rodrígues Silvio Martinelli Roberto Eduardo Bittar Rossana Pulcineli Vieira Francisco Marcelo Zugaib About the authors


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

Fetal growth retardation; Infant, small for gestational age; Birth weight; Prenatal diagnosis

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