Left and right myocardial performance indices in growth‐restricted fetuses: systematic review and meta‐analysis

Objectives: To evaluate alterations in fetal cardiac function in pregnancies complicated by fetal growth restriction (FGR) by synthesizing evidence on myocardial performance index (MPI) and its constituent parameters for both the left and right ventricles. The secondary objective was to explore the influence of timing of FGR onset (early vs late) on these parameters. Methods: We conducted a systematic review and meta-analysis of observational studies by searching PubMed/MEDLINE, EMBASE, Scopus, Web of Science and the Cochrane Central Register of Controlled Trials (CENTRAL) databases from inception until August 2025. Eligible studies compared fetal MPI, isovolumetric contraction time (ICT), ejection time (ET), isovolumetric relaxation time (IRT) and/or peak early-to-late diastolic filling velocity ratio (E/A ratio) between FGR fetuses and healthy controls. Data reported in original publications as median with interquartile range, range or 95% CI were converted to mean ± SD. A random-effects model was used to calculate the pooled standardized mean difference (SMD) with 95% CI. Prespecified subgroup analyses were performed based on ventricular laterality, timing of FGR onset and data presentation type. The protocol was registered with PROSPERO (registration number: CRD420251075193). Results: Fifteen studies, comprising 709 FGR fetuses and 867 controls, were included. Compared with controls, FGR fetuses exhibited significant left ventricular dysfunction, characterized by a higher left MPI (SMD, 0.85 (95% CI, 0.53-1.16)), prolonged left ICT (SMD, 0.53 (95% CI, 0.08-0.99)) and shorter left ET (SMD, -0.56 (95% CI, -0.84 to -0.29)). The most profound alteration was a prolongation of the left IRT in FGR cases (SMD, 2.48 (95% CI, 1.55-3.41)). Right ventricular assessment revealed a prolonged right IRT in FGR fetuses compared with controls (SMD, 1.90 (95% CI, 0.72-3.07)). Subgroup analysis showed that myocardial functional alterations affect both early- and late-onset FGR phenotypes, with early cases showing a non-significant trend toward more pronounced impairment. Sensitivity analysis including only studies that employed stricter diagnostic criteria for FGR confirmed these findings. Significant publication bias was detected for the analysis of left MPI and left IRT. Conclusions: FGR is associated with significant biventricular cardiac dysfunction, characterized primarily by impaired myocardial relaxation, as indicated by a markedly prolonged IRT. The IRT appears to be a more sensitive marker of cardiac compromise in FGR compared with the traditional E/A ratio. These findings support the use of MPI and its components as valuable adjunctive tools in the surveillance of FGR pregnancies. © 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.