Clinical and Experimental Obstetrics & Gynecology (CEOG) is published by IMR Press from Volume 47 Issue 1 (2020). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with S.O.G.
Change of autonomic nervous activity during pregnancy and its modulation of labor assessed by spectral heart rate variability analysis
Purpose of investigation: To elucidate the sequential changes of autonomic nervous activity during pregnancy, we examined heart rate variability on two positions and whether autonomic nervous activity affected duration of labor. Methods: Thirty-eight normal pregnant women were studied. Frequency domain parameters (HF, LF, LF/HF ratio) and heart rate were obtained by spectral HRV analysis in the supine and left recumbent position in three trimesters. Results: We found HF was significantly higher in early pregnancy, while the LF/HF ratio was significantly higher in late pregnancy. The LF/HF ratio was significantly lower when the left recumbent position was assumed. The LF/HF ratio was significantly higher in the longer labor group of primiparous women. Conclusion: Our findings demonstrate that sympathovagal balance shifted progressively from a higher vagal modulation towards a higher sympathetic modulation, and the recumbent position activated vagal activity. It is suggested that increased sympathetic activity in late pregnancy could affect the duration of labor.