Evaluation of the effects of indomethacin tocolytic treatment on fetal heart using modified myocardial performance index (Mod-MPI)

Indomethacin is one of the most effective and widely used tocolytic agents for treating threatened preterm labor and prolonging pregnancy. Nonetheless, data on its fetal effects, particularly regarding cardiac functions, remain limited. The primary aim of this study was to evaluate the effects of indomethacin treatment on fetal cardiac structures, the modified myocardial performance index (Mod-MPI), and hemodynamic parameters to establish evidence-based monitoring recommendations in cases of threatened preterm labor.

In this prospective study of 114 pregnant women, 57 cases diagnosed with threatened preterm birth received indomethacin tocolytic therapy, while 57 controls had uneventful pregnancies. Demographic characteristics, perinatal outcomes, Doppler measurements, cardiac structural measurements, Mod-MPI, and tricuspid regurgitation were compared between groups.

Doppler analysis revealed no significant differences except for umbilical artery pulsatility index, which was elevated in the indomethacin group (0.941 ± 0.160 vs. 0.869 ± 0.171, p = 0.023) due to vasoconstrictive effects from prostaglandin synthesis inhibition. Isovolumetric contraction and relaxation times were lower in the indomethacin group (42.3 ± 0.5 vs. 47.2 ± 2.7, p = 0.020; 49.3 ± 1.9 vs. 48.2 ± 1.8, p = 0.030). However, Mod-MPI did not differ significantly between the groups (0.464 ± 0.11 vs. 0.44 ± 0.09, p = 0.349). Although tricuspid regurgitation was observed in 14 of 57 fetuses (24.6%) exposed to indomethacin, perinatal outcomes were not significantly different.

Indomethacin treatment does not negatively affect fetal cardiac function or Mod-MPI. When tricuspid regurgitation occurs, increased monitoring is recommended rather than treatment cessation if other parameters remain stable.