# Ultrasound Measurement of the Fetal Adrenal Gland and Prediction of Preterm Birth

## TL;DR

This study shows that measuring a fetus's adrenal gland via ultrasound can help predict if a pregnant person is at high risk of delivering within seven days.

## Contribution

The study introduces fetal adrenal gland morphometry as a novel, noninvasive predictor of imminent preterm birth.

## Key findings

- The d/D ratio and corrected adrenal gland volume were significantly higher in pregnancies delivering within seven days.
- A logistic regression model using d/D ratio achieved an AUC of 0.88 with high sensitivity and specificity.
- The findings suggest integrating adrenal gland measurements into clinical tools for preterm birth risk assessment.

## Abstract

Introduction

Identifying a marker that is highly sensitive, specific, noninvasive, and cost-effective for predicting preterm labor remains a critical clinical priority. We propose that ultrasound assessment of fetal adrenal gland morphometry, especially measurement of adrenal gland volume, may help discriminate pregnancies at higher short-term risk of delivery among women presenting with threatened preterm labor.

Objective

The objective of the study is to evaluate the short-term discriminative performance of ultrasound-derived fetal adrenal gland morphometric parameters, particularly the fetal zone depth-to-total gland depth (d/D) ratio and corrected adrenal gland volume (cAGV), in identifying the risk of delivery within seven days in patients with threatened preterm labor.

Methods

This retrospective study included 52 singleton pregnancies between 28 and 35 weeks' gestation. Fetal adrenal gland dimensions and the fetal zone were measured via transabdominal ultrasound. Logistic regression and receiver operating characteristic (ROC) analysis were used to assess predictors of preterm birth within seven days of ultrasound evaluation.

Results

Both d/D ratio and cAGV were significantly higher in the early delivery group (p < 0.0001). Multivariable logistic regression identified d/D ratio as the strongest association with delivery within seven days. The model yielded an area under the curve (AUC) of 0.88. At the optimal probability threshold of 0.59, sensitivity was 85.7%, specificity 79.2%, positive predictive value (PPV) 82.8%, and negative predictive value (NPV) 83.3%.

Conclusion

Fetal adrenal morphometry, particularly d/D ratio and cAGV, can serve as valuable predictors of imminent preterm delivery and should be integrated into clinical assessment tools for symptomatic patients.