(481) Prediction of adverse neonatal outcomes by different birthweight standards

Our objective was to compare the prediction ability for adverse neonatal outcomes of Alexander and Fenton birthweight standards.


Study Design:

This was a secondary analysis of a previous study that included singleton pregnancies that underwent fetal growth assessment between 26 and 36 weeks of gestation. Exclusion criteria included fetuses with chromosomal or congenital malformations and those without delivery information. The prediction ability of both small for gestational age (SGA) and large for gestational age (LGA) small for gestational age (SGA) by the Fenton and Alexander birthweight charts for a composite of adverse neonatal outcomes (CANO) that included one or more of: neonatal intensive care unit admission, pH < 7.1, Apgar score < 7 at 5 minutes of life, seizures, respiratory distress syndrome, intraventricular hemorrhage grade III or IV, or neonatal death) was evaluated by comparing the area under the curve of receiver operating curve of clinical characteristics.


Results:

A total of 1054 neonates were included for analysis, 221 neonates were complicated with CANO, 99 met criteria for SGA and 111 for LGA by the Fenton chart and 139 and 124 by the Alexander standard. For SGA, the Fenton and Alexander standards had similar ability to predict CANO, AUC: 0.524 [0.499 -0.548] vs 0.537 [0.509 -0.565], p = 0.16. For LGA, the Fenton standard had a statistically significant better prediction ability for CANO, AUC: 0.534 [0.508 -0.548] vs 0.514 [0.489 -0.540], p = 0.026. However, both standards had poor prediction ability for adverse neonatal outcomes in SGA (figure 1) and LGA neonates (figure 2).


Conclusion:

The Fenton birthweight chart may better predictor of adverse neonatal outcomes than the Alexander chart for LGA neonates.  Both birthweight standards included in the present study, had poor prediction ability to detect CANO.