Association between fetal myocardial performance index and fetal heart rate monitoring: a prospective observational cohort study.

To evaluate whether the left myocardial performance index (MPI) changes in association with the fetal heart rate (FHR) tracing during labor. Women with term, singleton pregnancies, in labor were recruited to this prospective cohort study. Primary outcome: difference in left MPI between Category of fetal heart rate tracings. Secondary outcomes: differences in left MPI by FHR characteristics. Participants underwent ultrasound examination, during which fetal MPI was measured. Twenty-four laboring patients were recruited. There were 13 patients with Category I FHR, 11 patients with Category II FHR, and 0 patients with Category III FHR. Demographics were similar between the groups. MPI was not significantly different between fetuses with Category I or Category II FHR (0.67 versus 0.65,  = .385). MPI was significantly higher in fetuses with accelerations versus those without (0.71 versus 0.59,  = .045). MPI was not significantly different for fetuses with or without decelerations (0.65 versus 0.68,  = .350), between deceleration type (0.50 versus 0.64 versus, 0.75,  = .421), or between variability type (0.56 versus 0.68,  = .113). MPI of fetuses in term, laboring patients did not vary with differing FHR characteristics except for the presence or absence of accelerations.