Prediction of Neonatal Growth Restriction in Fetuses With Gastroschisis by Early Third Trimester Ultrasonography Utilizing Contemporary Birth Weight Percentiles.

Objective: To identify the estimated fetal weight (EFW) formula and threshold for the optimal prediction of fetal growth restriction (FGR) at 26-34 weeks' in fetuses with gastroschisis.

Methods: Late second and third trimester ultrasound data were used to calculate the EFW utilizing eight different formulas: Hadlock I-IV, Honarvar, Shepard, Siemer, and Warsof. EFW and birth weight percentiles were assigned from US population growth curves. FGR and small for gestational age (SGA) were defined as EFW and birth weight less than the tenth percentile for gestational age; Receiver operating characteristic (ROC) curves were used to compare formula performance for FGR diagnosis at 26-34 weeks' to identify an SGA birth weight.

Results: There were 170 newborns with gastroschisis; 46 (27%) were SGA. The mean gestational age at the time of ultrasound was 30.8 ± 1.7 weeks. The mean gestational age at birth was 36.3 ± 1.7 weeks. ROC curve analysis found the Hadlock III formula had the largest area under the curve (AUC) of 0.813 closely followed by Hadlock IV (AUC = 0.811) and Hadlock II (AUC = 0.808) for diagnosis of FGR correlating to neonatal SGA diagnosis. Hadlock II, Hadlock III, and Hadlock IV had the highest diagnostic accuracies when compared to the other EFW formulas.

Conclusions: The Hadlock II, Hadlock III, and Hadlock IV formulas have comparable predictive performance in the optimal identification of FGR in fetuses with gastroschisis at 26-34 weeks'. A threshold of an EFW less than the 25.2th percentile is suggested.