451: Is the intergrowth-21st growth standard superior to the customized approach for identifying pregnancies at risk for neonatal small for gestational age (SGA) and adverse outcomes?

Abstract

To determine if the Intergrowth-21 (IG-21) growth standard is better than the Customized standard for predicting pregnancies at risk for neonatal SGA and adverse outcomes. We performed a prospective observational study on women presenting for fetal growth assessment between 26 and 36 weeks gestation (GA). FGR was defined as the estimated fetal weight (EFW) < 10th percentile for GA using IG-21 and a Customized standard (Gardosi et al AJOG 2009 25.e1-7). Neonatal SGA was defined as birthweight < 10th percentile for GA by Alexander chart. Primary outcome was prediction of neonatal SGA. Secondary outcomes included neonatal intensive care unit (NICU) admissions, cord arterial pH < 7.1, 5 minute Apgar < 7, hypoglycemia, and composite adverse neonatal outcomes defined as the presence of one or more of the above outcomes and neonatal seizure, grade III or IV IVH or neonatal death. The discriminatory ability of each growth standard were compared using area under receiver operating characteristic curves (AUC). Parametric and non-parametric statistics were used to compare both standards. Of 1055 women meeting inclusion criteria, neonatal SGA was seen in 139 (13.2%), and a composite adverse neonatal outcome in 300 (28.4%). The sensitivity of the customized standard (38.8%) was higher than IG-21 (24.5%) for predicting neonatal SGA (Table); with AUC and 95% CI (0.67, 0.63-0.71 for customized; and 0.62, 0.58-0.65 for IG-21; p=0.003) FIGURE. Both standards were comparable and poor in predicting the composite adverse neonatal outcomes: AUC and 95% CI 0.52, 0.50-0.55 for customized ; and 0.51, 0.50-0.53 for IG-21 ; p=0.25. The customized standard is significantly better at predicting neonatal SGA compared to the Intergrowth-21st Century standard. The two standards are however, poor at identifying those at risk for immediate neonatal adverse outcome.View Large Image Figure ViewerDownload Hi-res image Download (PPT)