Fetal cardiac remodeling in second trimester in pregnancies with pre‐eclampsia and/or fetal growth restriction: deep‐learning‐based approach using population‐wide data

ABSTRACT Objective Pre‐eclampsia (PE) and fetal growth restriction (FGR) have been shown to impact fetal cardiac remodeling in the third trimester and postnatally, with evidence to suggest that this leads to increased long‐term cardiovascular risk. This study aimed to examine fetal cardiac remodeling in pregnancies with PE and/or FGR during the second trimester. Methods This was a retrospective nationwide cohort study of ultrasound images from routine screening at 18–22 weeks of gestation in Denmark. We included 139 430 singleton pregnancies that were conceived spontaneously for which at least one relevant standardized cardiac plane (four‐chamber view and/or three‐vessel view) was available from the second‐trimester scan. An artificial intelligence model performed automated segmentation and extraction of fetal cardiac biometric measurements. Data were collected for four groups: the reference group, defined as appropriate‐for‐gestational‐age (AGA) fetuses from a normotensive pregnancy ( n = 131 150); AGA fetuses from a PE pregnancy (AGA + PE group; n = 3095); FGR fetuses from a normotensive pregnancy (normotensive + FGR group; n = 4572); and FGR fetuses from a PE pregnancy (PE + FGR group; n = 613). Differences between groups in cardiac biometric measurements were presented as Z ‐scores adjusted for abdominal circumference at the second‐trimester scan. Results Compared with the reference group, fetuses in the PE + AGA group had significantly larger right‐sided heart structures, and the main pulmonary artery (MPA) and ventricular septum were wider. Fetuses in the normotensive + FGR group displayed significantly smaller cardiac structures, including smaller MPA and ascending aorta diameters, and increased left ventricular sphericity compared with the reference group. Fetuses in the PE + FGR group differed significantly from the reference group only in terms of smaller left atrial area, narrower ascending aorta and increased left ventricular sphericity. However, PE + FGR fetuses had significantly wider MPA and ventricular septum and larger right‐sided structures compared with normotensive + FGR fetuses, mimicking the features of the PE + AGA group, suggesting a distinct effect of PE on fetal cardiac remodeling. Conclusions Cardiac remodeling is evident as early as the second trimester, with distinct patterns of modulation in fetuses from pregnancies affected by PE vs FGR. In particular, PE is associated with an enlarged right heart and greater MPA diameter. Understanding these early differences in fetal cardiac morphology may improve risk prediction models and guide early intervention to improve long‐term cardiovascular outcome. © 2025 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.