Fetal adrenal gland volume: a novel method to identify women at risk for impending preterm birth

To investigate the risk of preterm birth (delivery at less than 37 weeks of gestation) by evaluating the fetal adrenal gland volume, hallmark of activation of the fetal hypothalamic-pituitary-adrenal axis, measured by 3-dimensional ultrasonography.

We performed 3-dimensional ultrasound examination of the fetal adrenal gland volume in 126 singleton fetuses, prospectively comparing those born to mothers with signs or symptoms of preterm labor (n=53) to control subjects (n=73). Multiplanar technique with rotational methods for measurement of fetal adrenal gland volume was performed by using Virtual Organ Computer-Aided Analysis (VOCAL) technology.

The fetal adrenal gland volume was successfully examined in 86.5% of the cases. There was a direct relationship between the fetal adrenal gland volume and estimated fetal weight. A corrected adrenal gland volume of greater than 422 mm3/kg was best in predicting preterm birth within 5 days from the time of the measurement. The sensitivity, specificity, and positive and negative likelihood ratios were 92%, 99%, 93.5, and 0.08, respectively. Multiple logistic regression analysis showed that the corrected adrenal gland volume was the only significant independent predictor factor of preterm birth within 5 days of measurement.

Corrected adrenal gland volume measurement may identify women at risk for impending preterm birth. This information can be generated noninvasively and in time for clinical decision making.

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