Effect of antenatal administration of thyrotrophin releasing hormone on fetal flow velocity waveforms

Drug exposure during pregnancy and fetal cardiac function - a systematic review

Background The aim of this systematic review was to describe the effects of drug exposure during pregnancy on fetal cardiac function. Methods We searched MEDLINE, Embase, Cochrane and SCOPUS for studies assessing fetal cardiac function in drug-exposed human pregnancies. Risk of bias was assessed by the Risk Of Bias In Non-randomized Studies of Interventions (ROBIN-I) tool. Results We included 32 studies on eight different drug groups. They included 51 outcome variables, which were all based on ultrasound techniques primarily assessing systolic function: pulsed wave Doppler, tissue Doppler imaging (TDI), and B- and M-mode. Overall, the risk of bias was moderate. β2 agonists increased the systolic velocity in the ductus arteriosus and the fetal heart rate. β-blockers caused unchanged or decreased systolic velocity of the pulmonary trunk. Corticosteroids increased the velocity in the ductus arteriosus. Furthermore, in growth-restricted fetuses with an increased myocardial performance index (MPI') on the right side, corticosteroids normalized this variable. Nonsteroidal anti-inflammatory drugs (NSAIDs), but not acetylsalicylic acid, increased the flow velocities in the ductus arteriosus, decreased the shortening fraction and increased the end-diastolic ventricular diameters. Metformin and insulin normalized the diastolic strain and global longitudinal strain in diabetic pregnancies. Highly active antiretroviral therapy (HAART) exposure increased the E/A ratio on the right side, prolonged the isovolumic relaxation time (IRT) and ejection time, shortened the isovolumic contraction time (ICT), and decreased left myocardial systolic peak velocities. Chemotherapy did not cause detectable changes. Conclusion Six of the eight drug groups caused detectable changes in fetal cardiac function. However, the evidence was hampered by only a few studies for some drugs.

Effects of thyrotropin-releasing hormone on human myometrium and umbilical vasculature in vitro

OBJECTIVE

The purpose of this study was to investigate the direct effects of thyrotropin-releasing hormone on isolated human myometrium that was obtained during pregnancy and on human umbilical vasculature in vitro.

STUDY DESIGN

Isolated human myometrial strips were dissected from biopsy specimens that were obtained at elective cesarean delivery and suspended for isometric recording under physiologic conditions. The effects of cumulative additions of thyrotropin-releasing hormone (10(-9)-10(-4) mol/L) on oxytocin-induced myometrial contractility were evaluated. The effects of thyrotropin-releasing hormone (10(-9)-10(-4) mol/L) on umbilical vessel (artery and vein) resistance in vitro were investigated with the use of isolated ring preparations.

RESULTS

Thyrotropin-releasing hormone exerted a significant concentration-dependent relaxant effect on pregnant human myometrial tissue, which ranged from 3.54% (10(-9) mol/L, P=.935) to a net cumulative total of 21.06% (10(-4) mol/L, P<.001). Thyrotropin-releasing hormone also exerted a concentration-dependent relaxant effect on human umbilical vasculature that ranged from 12.51% (10(-9) mol/L, P=.994) to a net cumulative total of 23.27%+/-4.87% (SEM, 10(-4) mol/L, P<.01) in umbilical artery. For umbilical vein, the relaxant effect ranged from 1.80% (10(-9) mol/L, P=.998) to a net cumulative total of 14.64% (10(-4) mol/L, P<.009).

CONCLUSION

Thyrotropin-releasing hormone exerts a significant relaxant effect in human myometrium and in human umbilical vasculature and highlights a potential physiologic role for this neuropeptide in these tissues. These findings have clinical implications for the therapeutic use of thyrotropin-releasing hormone antenatally.