First-Trimester Crown-Rump Length and Large for Gestational Age Newborns: What Correlation?
Marika Ylenia Rovetto1, Laura Sarno1, Giuseppe Gabriele Iorio1
1Department of Neuroscience, Reproductive Sciences and Dentistry, School of Medicine, University of Naples Federico II, Naples, Italy.
Journal of Clinical Ultrasound : JCU
|August 4, 2026
Summary
First-trimester crown-rump length (CRL) is linked to large-for-gestational-age (LGA) neonates. However, CRL alone has limited predictive power for identifying LGA risk in uncomplicated pregnancies.
Area of Science:
- Prenatal diagnostics
- Maternal-fetal medicine
- Obstetrics
Background:
- Large-for-gestational-age (LGA) neonates pose risks to maternal and infant health.
- Early identification of LGA risk is crucial for appropriate management.
- First-trimester ultrasound measurements, such as crown-rump length (CRL), are routinely performed.
Purpose of the Study:
- To investigate the association between first-trimester crown-rump length (CRL) and the risk of delivering large-for-gestational-age (LGA) neonates.
- To assess the predictive accuracy of CRL for identifying LGA neonates in uncomplicated pregnancies.
Main Methods:
- Prospective study of 333 singleton pregnancies undergoing first-trimester ultrasound.
- Standardized CRL measurements were performed; gestational age was confirmed or adjusted based on CRL.
- Multivariate regression and receiver operating characteristic (ROC) curve analyses were used to evaluate CRL's predictive value for LGA, defined by INTERGROWTH-21st standards.
Main Results:
- A significant association was found between first-trimester CRL and the risk of LGA neonates.
- ROC curve analysis yielded an area under the curve (AUC) of 0.665, indicating modest discriminative performance.
- The optimal CRL cut-off demonstrated 63.6% sensitivity, 69.3% specificity, and a high negative predictive value of 96.4% for LGA.
Conclusions:
- First-trimester CRL is associated with fetal overgrowth, a potential indicator for LGA.
- CRL alone exhibits limited predictive accuracy for identifying LGA neonates.
- The clinical utility of CRL may be enhanced when incorporated into multifactorial predictive models for LGA risk assessment.
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