Effects of maternal central hemodynamics on fetal heart rate patterns

This study was undertaken to evaluate the effects of maternal central hemodynamics on fetal heart rate patterns near term, with special regard to the maternal body position.

Brief non-stress test and bioimpedance cardiography were carried out in the supine position, then repeated in a full left lateral decubitus position of mothers with singular, 36-39 week-old normal pregnancies in 106 cases. Computer-aided data were processed by SPSS statistic program.

Due to the appearance of inferior vena cava syndrome, examinations had to be interrupted in 6 cases. Analysis of 100 complete registrations revealed a significantly increased number of accelerations, overall and short-term variations, and longer high episodes with lower basal fetal heart rates were found in the lateral decubitus than in the supine maternal position. Turning to the left resulted in a significant increase of the stroke volume; however, due to decreasing pulse rate, the cardiac output remained unchanged. Parameters of non-stress test showed correlations to hemodynamic indices. In the supine position, the short-term variation correlated with cardiac output (r=0.232, p=0.020); in the left lateral position, the number of accelerations correlated with stroke volume (r=0.221, p=0.027) and cardiac output (r=0.220, p=0.028). Changes of stroke volume due to altered body position correlated to similar changes of overall variation (r=0.264, p=0.018), and marginally to those of short-term variation (r=0.221, p=0.051).

Maternal central hemodynamics influences fetal heart rate patterns in connection with different maternal body position.