(463) Cardiac remodeling in fetuses exposed to threatened preterm labor delivered near or at term

To evaluate whether fetuses exposed to threatened preterm labor (PTL) without intra-amniotic infection or inflammation (IAI) and delivered after 34 weeks show cardiac remodeling and dysfunction at admission, and whether these changes persist one month later.

Study Design:

This prospective cohort study included singleton pregnancies with PTL between 23–34 weeks, confirmed absence of IAI via amniocentesis, a latency to delivery exceeding four weeks, and birth beyond 34 weeks. Fetal echocardiography was performed at admission and one month later. A gestational age-matched control group was also assessed. Amniotic fluid levels of Troponin-I and NT-proBNP were compared to biobank samples at similar gestational ages.

Results:

We analyzed 32 fetuses with threatened PTL and 43 controls, with comparable baseline characteristics including fetal sex, gestational age, and fetal growth. 84% of fetuses in the threatened PTL group were born at term. At admission (around 29 weeks of gestation), the threatened PTL group already showed signs of cardiac remodeling, including more globular hearts, enlarged right atrial areas, and subclinical diastolic dysfunction. Systolic function was mildly increased. These changes affected exclusively the right heart. Troponin-I levels were significantly higher, and NT-proBNP was detectable in 25% of threatened PTL cases compared to none in controls. One month later (around 34 weeks of gestation), systolic parameters had normalized, but signs of remodeling (lower sphericity index, larger right ventricular area) and diastolic dysfunction (prolonged inflow times) persisted, primarily affecting the right heart.

Conclusion:
Fetuses exposed to threatened PTL without IAI and delivered near or at term exhibit persistent cardiac remodeling and subclinical diastolic dysfunction. Elevated amniotic fluid Troponin-I at admission support these early echocardiographic findings. These results help identify a previously unrecognized high-risk neonatal subgroup, born at or near term, that could benefit from targeted follow-up and early preventive interventions.