NEW YORK (Reuters Health) - Ultrasonic evaluation of fetal adrenal glands may be useful in identifying women who are at risk for preterm birth, according to a report in the April issue of Obstetrics and Gynecology.

Changes in placental hormones that lead to increased uterine activity and preterm birth are known to be mediated by the fetal hypothalamic-pituitary-adrenal axis, resulting in increased secretory activity of the adrenal glands. Previous reports have suggested that this change in activity is accompanied by an increase in adrenal gland volume. Therefore, measuring this volume might be useful in predicting preterm birth.

To investigate, Dr. Ozhan M. Turan, from the University of Maryland School of Medicine in Baltimore, and colleagues assessed fetal adrenal gland volume in 126 singleton pregnancies, including 53 with signs or symptoms of preterm labor and 73 without such signs.

The researchers were able to determine the adrenal gland volume in 86.5% of cases.

The volume of the gland was directly related to the estimated fetal weight, the report indicates. Moreover, a volume of 422 mm3/kg or greater was predictive of preterm birth within the next 5 days. The associated sensitivity and specificity were 92% and 99%, respectively, with positive and negative predictive likelihood ratios of 93.5 and 0.08, respectively.

"Our results demonstrate that fetal adrenal gland volume is a reproducible, accurate, and novel noninvasive method of predicting preterm birth," the authors conclude. "Given the body of evidence that suggests the fetus plays a role in the initiation of parturition, these results are biologically plausible, and fetal adrenal gland volume should be further evaluated as a predictor of preterm birth, either alone or in combination with other useful markers."