Midtrimester Ultrasound Predictors of Small-for-Gestational-Age Neonates

Area of Science:

• Perinatal Medicine
• Fetal Ultrasound
• Neonatal Outcomes

Background:

• Small-for-gestational-age (SGA) neonates are at increased risk for adverse outcomes.
• Accurate prediction of SGA in mid-gestation is crucial for timely intervention.
• Ultrasound biometry, including estimated fetal weight (EFW) and abdominal circumference (AC), is commonly used for fetal growth assessment.

Purpose of the Study:

• To evaluate the predictive accuracy of mid-gestation EFW and AC percentiles for identifying term small-for-gestational-age (SGA) neonates.
• To determine if a specific percentile cutoff exists for EFW or AC at the 18- to 24-week ultrasound (US) to predict SGA.
• To inform clinical counseling regarding fetal growth parameters.

Main Methods:

• Retrospective case-control study of uncomplicated singleton gestations.
• Inclusion criteria: term neonates with birth weight (BW) below the 10th percentile (SGA cases) and BW between the 10th and 90th percentiles (controls).
• Analysis of 18- to 24-week US data, focusing on EFW and AC percentiles, and correlation with BW.

Main Results:

• A total of 549 SGA neonates and 593 control neonates were analyzed.
• EFW and AC percentiles demonstrated poor predictive ability for SGA neonates (AUCs 0.68 and 0.69, respectively).
• Similar low predictive accuracy was observed for predicting neonates with BW below the 5th percentile.

Conclusions:

• No specific tipping point or cutoff for EFW or AC percentile at mid-gestation ultrasound can reliably predict term SGA neonates.
• These findings are valuable for counseling pregnant women about fetal growth parameters and the potential need for follow-up imaging.
• Current mid-gestation biometric parameters have limitations in predicting SGA, highlighting the need for further research into predictive models.