Fetal adrenal gland measurements as predictors of spontaneous preterm birth: a systematic review and meta-analysis

Abstract Purpose To evaluate the diagnostic performance of fetal adrenal gland biometry, specifically corrected adrenal gland volume (cAGV) and fetal zone (FZ), for predicting spontaneous preterm birth (PTB) and delivery within 7 days after ultrasound assessment primarily in symptomatic pregnancies. Methods A Systematic review and meta-analysis (SRMA) was conducted in accordance with the PRISMA-DTA statement. MEDLINE, Embase, and Scopus were searched through August 31, 2025. Diagnostic accuracy was pooled using a bivariate random-effects model when feasible; AUC and I 2 were obtained using complementary random-effects split component synthesis. Results Thirteen studies (1,620 singleton pregnancies) were included. For cAGV predicting PTB < 37 weeks (5 studies; n = 677), pooled sensitivity and specificity were 91% (95% CI 82–95%) and 88% (95% CI 77–94%), with area under the curve (AUC) of 0.95 (95% CI 0.86–0.98) and I 2 = 0%. For delivery within 7 days (4 studies; n = 495), pooled sensitivity and specificity were 82% (95% CI 67–91%) and 87% (95% CI 64–96%), with an AUC of 0.84 (95% CI 0.59–0.95) and I 2 = 93.8%. For the FZ depth-to-total gland depth ratio (d/D), accuracy was lower (AUC 0.81 for PTB and 0.70 for delivery within 7 days), with heterogeneity I 2 = 0% for PTB and 87.2% for delivery within 7 days. Conclusion Fetal adrenal gland biometry, particularly cAGV, shows promising diagnostic performance for predicting spontaneous PTB and delivery within 7 days. FZ d/D demonstrates lower diagnostic accuracy, while substantial heterogeneity in short-term delivery analyses warrants cautious interpretation.