Customized versus Population Growth Standards for Morbidity and Mortality Risk Stratification Using Ultrasonographic...

Area of Science:

• Obstetrics and Gynecology
• Perinatal Medicine
• Fetal Development

Background:

• Accurate fetal growth assessment is crucial for predicting adverse perinatal outcomes.
• Current population-based fetal growth standards may exhibit biases and have limited predictive accuracy.

Purpose of the Study:

• To compare the performance of ultrasonographic customized and population-based fetal growth standards in predicting adverse perinatal outcomes.
• To evaluate the diagnostic accuracy of estimated fetal weight (EFW) percentiles for fetal growth restriction (FGR).

Main Methods:

• Secondary analysis of the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be.
• EFW percentiles were assigned using Hadlock population standard and a customized standard (www.gestation.net) at 22–29 weeks' gestation.
• Area under the curve (AUC) was used to compare prediction of composite and severe composite perinatal morbidity.

Main Results:

• The population standard identified more cases of FGR (5.5%) than the customized standard (3.5%).
• Neither standard effectively predicted composite perinatal morbidity.
• The customized standard showed a slightly better, yet poor, prediction for severe perinatal morbidity (AUC 0.56 vs. 0.54).
• The population standard demonstrated significant racial/ethnic and sex biases in FGR diagnosis, which were absent with the customized standard.

Conclusions:

• EFW percentile alone poorly predicts perinatal morbidity at 22–29 weeks' gestation using either standard.
• The customized standard provides more equitable FGR detection across racial/ethnic and sex groups compared to the population standard.
• Population-based standards may misclassify FGR risk, overdiagnosing it in low-risk groups and underdiagnosing it in high-risk groups.