Fetal Adrenal Gland Biometry and Middle Adrenal Artery Doppler in Pregnancies Presenting with Preterm Labor: A Prospective Case–Control Study

Q: What are the key findings of this study?

Pregnancies with preterm labor had larger fetal adrenal volume (1.53 vs 1.08 cm³), lower middle adrenal artery PI (1.11 vs 1.46), and higher NICU admission (OR 14.0, 95% CI 2.82–69.56; p<0.001).

Q: What is the clinical evidence from this study?

Study design: Case-Control. Population: Preterm labor (n=60). Intervention: Preterm labor presentation (evaluated with fetal adrenal gland biometry and middle adrenal artery Doppler) vs. Gestational age-matched asymptomatic controls. Primary outcome: Neonatal intensive care unit (NICU) admission (OR 14.0, 95% CI 2.82–69.56, p=< 0.001).

Q: What question did this study set out to answer?

To compare fetal adrenal gland volume, fetal zone depth, and middle adrenal artery pulsatility index between pregnancies presenting with preterm labor and asymptomatic controls, and evaluate their relationships with delivery timing and neonatal outcomes.

Belgin Savran Üçok; Özgür Volkan Akbulut; Sadun Sucu; Mustafa Bağcı; İbrahim Buğra Bahadır; Kadriye Yakut Yucel

doi:10.3390/jcm15031192

February 3, 2026Journal of Clinical MedicineOpen Access

Fetal Adrenal Gland Biometry and Middle Adrenal Artery Doppler in Pregnancies Presenting with Preterm Labor: A Prospective Case–Control Study

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Key result

Preterm labor is linked to ~14-fold higher odds of NICU admission alongside fetal adrenal changes.

OR 14.0
95% CI 2.82–69.56
P<0.001
n=60

Key Points

To compare fetal adrenal gland volume, fetal zone depth, and middle adrenal artery pulsatility index between pregnancies presenting with preterm labor and asymptomatic controls, and evaluate their relationships with delivery timing and neonatal outcomes.
Prospective analytical cross-sectional case–control study of 60 singleton pregnancies (30 presenting with preterm labor and 30 gestational age-matched asymptomatic controls) evaluated at a tertiary perinatology unit between 24 + 0 and 36 + 6 weeks’ gestation.
Ultrasound assessments at enrollment included transvaginal cervical length, transabdominal fetal adrenal gland volume (AGV), fetal zone (FZ) depth, and middle adrenal artery pulsatility index (MAA-PI), alongside calculated corrected AGV (cAGV = AGV/estimated fetal weight) and the fetal zone–total gland depth ratio.
Compared with controls, the preterm labor group had shorter cervical length (12.5 vs. 33.5 mm, p < 0.001), higher AGV (1.53 vs. 1.08 cm3, p < 0.001), greater FZ depth (7.45 vs. 5.30 mm, p < 0.001), lower MAA-PI (1.11 vs. 1.46, p < 0.001), and higher cAGV (0.87 vs. 0.59, p < 0.001).
Pregnancies presenting with preterm labor delivered earlier (median 33 + 0 vs. 36 + 2 weeks, p < 0.001), had lower birthweight (median 1875 vs. 3188 g, p < 0.001), and had more frequent NICU admissions (50.0% vs. 6.7%; OR 14.0, 95% CI 2.82–69.56; p < 0.001).
Within the preterm labor group, gestational age at delivery correlated positively with cervical length (ρ = 0.900, p < 0.001) and MAA-PI (ρ = 0.770, p < 0.001), and negatively with AGV (ρ = −0.770, p < 0.001), FZ depth (ρ = −0.733, p < 0.001), and cAGV (ρ = −0.953, p < 0.001).

Study Design

Type

Case-Control (n=60)

Multicenter

No

PICO

P

Population

60 pregnant women with singleton pregnancies between 24 + 0 and 36 + 6 weeks' gestation (30 presenting with preterm labor and 30 gestational age-matched asymptomatic controls), free of maternal systemic disease or major fetal anomalies, followed until delivery.

E

Exposure / Comparator

Preterm labor presentation (evaluated with fetal adrenal gland biometry and middle adrenal artery Doppler) vs Gestational age-matched asymptomatic controls

O

Primary Outcome

Neonatal intensive care unit (NICU) admission — OR 14.0 (2.82–69.56), p=< 0.001

Main Result

Odds Ratio: 14 (95% CI 2.82–69.56)

Absolute Event Rate: 50% vs 6.7%

p-value: p=< 0.001

Limitations

Single-center design with a modest sample size (N=60).
Controls were defined as asymptomatic at enrollment rather than strictly by term delivery (only 36.7% of controls delivered at ≥37 + 0 weeks).
Post hoc fetal size adjustment was performed using retrospectively retrieved estimated fetal weight, and abdominal circumference was not consistently available.
Inter- and intraobserver reproducibility of ultrasound measurements were not assessed.
Statistical analysis was primarily univariable without multivariable modeling or predefined short-term time-to-delivery thresholds.

Implication

Case-control study compares adrenal metrics in preterm labor versus asymptomatic pregnancies, indicating potential risk markers.

Abstract

Objective: This study aimed to compare fetal adrenal gland volume (AGV), fetal zone (FZ) depth, and middle adrenal artery pulsatility index (MAA-PI) between pregnancies presenting with preterm labor and gestational age-matched asymptomatic controls, and to evaluate size-adjusted adrenal metrics (corrected AGV [cAGV] and fetal zone–total gland depth ratio) in relation to gestational age at delivery and neonatal outcomes. Methods: This prospective analytical cross-sectional (case–control) study included 60 singleton pregnancies (30 with preterm labor and 30 asymptomatic controls) evaluated at a tertiary perinatology unit between 24 + 0 and 36 + 6 weeks’ gestation. Transvaginal cervical length and transabdominal fetal adrenal measurements (AGV, FZ depth, and MAA-PI) were obtained at enrollment. Estimated fetal weight (EFW) at the index scan was retrieved, and corrected AGV (cAGV = AGV/EFW) and fetal zone–total gland depth ratio were calculated. Outcomes were gestational age at delivery, birthweight, Apgar scores, and neonatal intensive care unit (NICU) admission. Nonparametric group comparisons and Spearman correlations were used. Results: Gestational age at ultrasound was identical between groups (median 31 + 6 weeks). Compared with controls, the preterm labor group had shorter cervical length (12.5 vs. 33.5 mm, p < 0.001), higher AGV (1.53 vs. 1.08 cm3, p < 0.001) and FZ depth (7.45 vs. 5.30 mm, p < 0.001), and lower MAA-PI (1.11 vs. 1.46, p < 0.001). EFW at the index scan did not differ between groups (p = 0.900). Corrected AGV (cAGV) was higher in the preterm labor group (0.87 (0.76–1.06) vs. 0.59 (0.51–0.70), p < 0.001), and the fetal zone–total gland depth ratio was higher (0.328 (0.312–0.346) vs. 0.263 (0.241–0.278), p < 0.001). The preterm labor group delivered earlier (33 + 0 vs. 36 + 2 weeks, p < 0.001), had lower birthweight (1875 vs. 3188 g, p < 0.001), and more frequent NICU admission (50.0% vs. 6.7%; odds ratio 14.0, 95% CI 2.82–69.56; p < 0.001). Within the preterm labor group, gestational age at delivery correlated positively with cervical length (ρ = 0.900) and MAA-PI (ρ = 0.770) and negatively with AGV (ρ = −0.770) and FZ depth (ρ = −0.733), all p < 0.001; correlations were stronger for cAGV (ρ = −0.953, p < 0.001). Conclusions: Enlarged fetal adrenal gland volume and fetal zone depth together with reduced middle adrenal artery pulsatility index are associated with preterm labor and earlier delivery. Size-adjusted adrenal metrics (cAGV and fetal zone–total gland depth ratio) remained significantly different between groups, supporting these measures as potential adjuncts for risk stratification at presentation.

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Cite This Study

Üçok et al. (2026) conducted a case-control in Preterm labor (n=60). Preterm labor presentation (evaluated with fetal adrenal gland biometry and middle adrenal artery Doppler) vs. Gestational age-matched asymptomatic controls was evaluated on Neonatal intensive care unit (NICU) admission (OR 14.0, 95% CI 2.82–69.56, p=< 0.001). Pregnancies with preterm labor had larger fetal adrenal volume (1.53 vs 1.08 cm³), lower middle adrenal artery PI (1.11 vs 1.46), and higher NICU admission (OR 14.0, 95% CI 2.82–69.56; p<0.001).

synapsesocial.com/papers/698435b9f1d9ada3c1fb4d1d https://doi.org/10.3390/jcm15031192

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Fetal Adrenal Gland Biometry and Middle Adrenal Artery Doppler in Pregnancies Presenting with Preterm Labor: A Prospective Case–Control Study

Key Points

Study Design

PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

Fetal Adrenal Gland Biometry and Middle Adrenal Artery Doppler in Pregnancies Presenting with Preterm Labor: A Prospective Case–Control Study

Key Points

Study Design

PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

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