Incidence of small for gestational age neonates, according to the Fenton and Intergrowth-21st curves in a level II maternity

Objective: To compare the incidence of small for gestational age infants among late preterm and term newborns, using the Fenton and Intergrowth-21st curves. Methods: Observational and retrospective study with newborns in a level II maternity. The study was approved by the Institution's Ethics Committee. Live births from July 2007 to February 2009 with a gestational age from 34 to 41 weeks and seven days were included. Neonates with incomplete data were excluded. Appropriate weight for gestational age was assessed by the Fenton and Intergrowth-21st intrauterine growth curves, considering birth weight <10th percentile as small for gestational age. The degree of agreement between the two curves was assessed by the Kappa coefficient. Numerical variables were compared using the Student t-test or the Mann-Whitney. Categorical variables were compared using the chi-square test. Statistical analyzes were performed using SPSS17 (R) software, considering significant, p<0.05. Results: We included 2849 newborns with a birthweight of 3210 +/- 483 g, gestational age of 38.8 +/- 1.4 weeks; 51.1% male. The incidence of small for gestational age in the full sample was 13.0 vs. 8.7% (p<0.001, Kappa=0.667) by the Fenton and I ntergrowth-21st curves, respectively. Among late pre term, the incidence of small neonates was 11.3 vs. 10.9% (p<0.001; Kappa=0.793) and among full-term infants it was 13.1% vs. 8.5% (p<0.001; Kappa=0.656), respectively for the Fenton and Intergrowth-21st curves. Conclusions: The incidence of small for gestational age newborns was significantly higher using the Fenton curve, with greater agreement between the Fenton and Intergrowth-21st curves among late preterm, compared to full term neonates.

Automated summary

The study aimed to compare the incidence of small for gestational age infants among late preterm and term newborns using the Fenton and Intergrowth-21st curves. Results showed a significantly higher incidence of small for gestational age newborns with the Fenton curve, with greater agreement between the Fenton and Intergrowth-21st curves among late preterm infants compared to full-term neonates.