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New Study: Can First-Trimester Ultrasound Predict FGR?

•Posted inObstetrics and Gynaecology

The First-trimester Placental Ultrasound (FirstPLUS) study recently confirmed that incorporating first-trimester placental volume (FTPV) significantly improves the ability to predict Fetal Growth Restriction (FGR). This new finding offers clinicians a vital tool for early risk stratification. Specifically, a low Placental volume FGR Z-score emerged as an independent risk factor for subsequent FGR. Therefore, integrating this simple measurement into existing screening models is crucial.

The Role of First-Trimester Placental Volume (FTPV)

Researchers used data from 3,500 pregnancies in the FirstPLUS longitudinal study. They performed a routine ultrasound and three-dimensional placental sonography between 11+2 and 14+1 weeks’ gestation. Furthermore, the OxNNet toolkit provided automated placental segmentation and accurate volume calculation. Ultimately, 250 pregnancies (7.1%) in the final cohort developed FGR. The analysis confirmed that low FTPV constitutes a significant risk factor for FGR. Low FTPV showed an odds ratio (OR) of 1.736 for FGR per unit decrease in the FTPV Z-score. Consequently, measuring placental volume early in pregnancy provides critical prognostic information about the utero-placental interface.

Optimizing Predictive Models for FGR

The study compared predictive models both with and without the inclusion of FTPV. The baseline model included maternal factors and established first-trimester biomarkers (serum PAPP-A, mean arterial blood pressure, and uterine artery pulsatility index). Integrating FTPV into this model significantly enhanced its discriminative ability. The Area Under the Curve (AUC) for predicting all FGR cases increased from 0.78 to 0.79 ($P=0.005$). Moreover, a dedicated subgroup analysis focused on normotensive FGR. Indeed, adding FTPV to the model for predicting normotensive FGR increased the AUC from 0.77 to 0.78 ($P=0.01$). This clearly demonstrates the added value of the FTPV Z-score. Conversely, the model’s AUC for predicting preterm FGR did not show a statistically significant difference with the inclusion of FTPV. Investigators suggest a lack of statistical power likely caused this result.

Clinical Impact of Placental volume FGR Screening

The FirstPLUS findings underscore the importance of early placental assessment. Globally, FGR is a major contributor to perinatal morbidity and mortality. Therefore, an effective first-trimester screening test is highly desirable. Early identification facilitates enhanced surveillance and timely intervention, ultimately improving neonatal outcomes. Furthermore, studies in India support the use of placental biometry, volume, and uterine artery Doppler in the first trimester for predicting Early-Onset FGR. Physicians should consider the FTPV Z-score as a valuable, objective marker in their risk stratification protocols.

Frequently Asked Questions

Q1: What new information does the FirstPLUS study provide?

The study validates that first-trimester placental volume (FTPV) is an independent predictor of Fetal Growth Restriction (FGR). Furthermore, incorporating FTPV Z-score into multi-marker predictive models significantly improves the overall detection rate for FGR, especially in normotensive women.

Q2: Which factors were included in the FGR predictive model?

The logistic regression model included maternal factors, first-trimester biomarkers (serum PAPP-A, mean arterial blood pressure, and uterine artery pulsatility index), and the OxNNet-derived FTPV.

Q3: Is a low FTPV associated with a higher risk of FGR?

Yes. Low FTPV was a significant risk factor, with an odds ratio of 1.736 for FGR per unit decrease in the FTPV Z-score.

References

  1. Mathewlynn S et al. First-trimester Placental Ultrasound (FirstPLUS) study: prediction of fetal growth restriction using OxNNet-derived first-trimester placental volume. Ultrasound Obstet Gynecol. 2025 Dec 06. doi: 10.1002/uog.70146. PMID: 41351882.
  2. Salsabila B, et al. Volume and vascularity: Using ultrasound to unlock the secrets of the first trimester placenta. Placenta. 22 Mar 2022. doi: 10.1016/j.placenta.2022.03.007.
  3. Kalia S, et al. Placental biophysical model for prediction of early onset fetal growth restriction in first and second trimester of pregnancy: A prospective cohort study. Placenta. 2024 Sep 2;154:153-159. doi: 10.1016/j.placenta.2024.07.003.
  4. Stampalija T, et al. First trimester placental volume is reduced in hypertensive disorders of pregnancy associated with small for gestational age fetus. J Matern Fetal Neonatal Med. 2021 Apr;34(8):1304-1311. doi: 10.1080/14767058.2019.1636026.