Longitudinal assessment of fetal myocardial performance index in normal pregnancy using spectral tissue Doppler.

OBJECTIVE: Although spectral tissue Doppler imaging is recognized as the optimal method for assessing the fetal myocardial performance index (MPI), longitudinal reference ranges for fetal MPI measured using spectral tissue Doppler have not been established. Our objective was to use spectral tissue Doppler data to establish gestational-age-specific reference ranges from 12-33 weeks for left and right ventricular fetal MPI. METHODS: This was a prospective longitudinal study of women aged 18-35 years, with a body mass index below 30 kg/m2 and a singleton pregnancy conceived spontaneously. Fetal MPI measurements were obtained in the first, second and third trimesters and MPI was determined using spectral tissue Doppler imaging. A generalized additive model for location, scale and shape (GAMLSS) was used to explore the relationship between fetal MPI and gestational age. Model fit was assessed by checking the normality of estimated Z-scores across the fitted range and independency from gestational age. RESULTS: Median fetal MPI was determined for the right and left ventricles at 12-13 weeks, 20-21 weeks and 32-33 weeks' gestation in 90 fetuses. Using multilevel regression modeling, weekly reference ranges for each gestational age were created to provide a continuous characterization of normal fetal MPI assessed using spectral tissue Doppler throughout pregnancy. Percentile reference ranges (5th, 10th, 25th, 50th, 75th, 90th and 95th) for right and left ventricular fetal MPI were generated from these models, capturing normal variability across gestation. CONCLUSION: We have established gestational-age-specific reference ranges for left and right ventricular fetal MPI using spectral tissue Doppler imaging, thus providing clinicians with an important tool for the early detection of fetal cardiac dysfunction in high-risk pregnancies. © 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.