Ultrasound Obstet Gynecol. 2026 Aug 16. doi: 10.1002/uog.70304. Online ahead of print.
ABSTRACT
OBJECTIVE: To evaluate whether fetuses exposed to threatened preterm labor (PTL) without intra-amniotic infection or inflammation (IAI), who were born ≥ 34 weeks' gestation, show signs of cardiac remodeling and dysfunction at admission and 4 weeks after the episode of threatened PTL.
METHODS: This was a prospective cohort study conducted at two tertiary referral centers including pregnant patients admitted between September 2018 and April 2021. The study group comprised women with singleton pregnancies and intact membranes who were admitted with a diagnosis of PTL between 23 and 34 weeks' gestation. Pregnancies were eligible for inclusion if amniocentesis was performed at admission and ruled out the occurrence of IAI. Exclusion criteria included latency to delivery shorter than 4 weeks and delivery < 34 weeks. Fetal echocardiography was performed within 72 h after admission and was repeated at follow-up 4 weeks later. A control group of singleton pregnancies without PTL or preterm prelabor rupture of membranes (PPROM), matched with the study group at a ratio of 1:1 by gestational age at ultrasound, was also evaluated. Fetal cardiac morphology and function were assessed using a standardized echocardiographic protocol, and compared between the two groups. Amniotic fluid troponin I and N-terminal pro-brain natriuretic peptide (NT-proBNP) concentrations were measured in the study group at the time at which amniocentesis was performed, and were compared with 20 amniotic fluid samples from the Clinic-IDIBAPS Biobank that had been collected for indications other than PTL/PPROM or cardiac pathology.
RESULTS: A total of 32 fetuses exposed to threatened PTL (of which 84.4% were born at term) and 43 controls were compared. At admission, fetuses exposed to threatened PTL already showed signs of cardiac remodeling compared with controls, including a more globular cardiac shape (median global sphericity index, 1.17 vs 1.23; P = 0.012), an increased right atrial area-to-heart area ratio (median, 0.18 vs 0.16; P = 0.006) and early signs of diastolic dysfunction (median lower tricuspid E/A ratio, 0.65 vs 0.72; P = 0.027) and increased systolic function (median tricuspid annular plane systolic excursion, 6.5 vs 6.0 mm; P = 0.036). At admission, the threatened-PTL group also showed significantly higher amniotic fluid troponin-I levels (median, 1222.8 pg/mL vs 841.3 pg/mL; P = 0.026). Amniotic fluid NT-proBNP was detectable in 25% of these cases, compared with none in the control group. At 4 weeks after the first ultrasound evaluation, in fetuses from mothers with threatened PTL, we observed that systolic function had normalized but cardiac remodeling persisted. These fetuses still exhibited a more globular cardiac shape (median global sphericity index, 1.16 vs 1.25; P = 0.036), and they now had a larger right ventricle (RV) (median RV area-to-heart area ratio, 0.26 vs 0.24; P = 0.037) without cardiomegaly. Diastolic function remained altered, with prolonged tricuspid inflow duration (median inflow time fraction, 0.39 vs 0.35; P = 0.001) and longer atrial contraction (median atrial time fraction, 0.23 vs 0.20; P = 0.039).
CONCLUSIONS: Fetuses exposed to threatened PTL without IAI, who were born ≥ 34 weeks' gestation, exhibited signs of cardiac remodeling and subclinical diastolic dysfunction of the RV at admission that persisted for at least 4 weeks. Early identification of threatened PTL may provide opportunities to apply preventive strategies aimed at improving long-term cardiovascular health. © 2026 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.
PMID:42604600 | DOI:10.1002/uog.70304