Objective: 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.
Methods: 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.
Results: 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.
Conclusion: 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.
Level of evidence: II.