Assessment of fetal cardiac structure and function in hyperthyroid pregnancies using fetal heart quantification...

Hyperthyroidism complicates approximately 2.4% of pregnancies and is associated with adverse outcomes such as preterm birth, placental abruption, and fetal demise. However, its specific effects on fetal cardiac structure and function remain poorly characterized. This study aimed to quantitatively assess the morphological and functional changes in the fetal heart associated with maternal hyperthyroidism using novel fetal heart quantification (HQ) technology.

In total, 282 pregnant women were enrolled in this prospective study, of whom 197 had healthy pregnancies and 85 had hyperthyroid pregnancies. All the participants underwent detailed fetal echocardiography using a GE Voluson E10 system. The fetal HQ analysis was used to evaluate cardiac geometry parameters, such as the global sphericity index (GSI) and ventricular dimensions, and functional parameters, such as global longitudinal strain (GLS) and fractional area change (FAC).

Compared with the healthy controls, the fetuses in the hyperthyroidism group had a larger left ventricular (LV) systolic area (2.68±0.14 vs. 2.27±0.11 cm², P<0.001) and right ventricular (RV) systolic area (3.23±0.31 vs. 2.74±0.23 cm², P<0.001), as well as increased diastolic areas (LV diastolic area: 3.86±0.35 vs. 3.21±0.29 cm²; RV diastolic area: 4.16±0.38 vs. 3.63±0.30 cm²; both P<0.001). The fetuses in the hyperthyroidism group also showed altered cardiac geometry, including a lower GSI (1.19±0.11 vs. 1.24±0.16, P=0.009), and impaired systolic function reflected by less negative LV GLS values (-21.8%±6.2% vs. -23.4%±5.1%, P=0.024) and reduced LV FAC (37.3%±7.9% vs. 39.7%±8.5%, P=0.027). The correlation analyses suggested potential associations between maternal thyroid hormone levels and fetal cardiac parameters.

Maternal hyperthyroidism significantly affects fetal cardiac morphology and function. Fetal HQ provides valuable quantitative insights into these changes, supporting its clinical utility in the prenatal evaluation of at-risk pregnancies.