441 International Journal of Medicine and Public Health | Oct-Dec 2014 | Vol 4 | Issue 4 Pritesh Hariprasad Gandhi, Hemant B. Mehta, Ashish V. Gokhale 1 , Chetan B. Desai, Pradnya A. Gokhale, Chinmay J. Shah Departments of Physiology and 1 Obstetrics and Gynaecology, Government Medical College, Sir T Hospital, Bhavnagar, Gujarat, India Address for the Correspondence: Dr. Pritesh Hariprasad Gandhi, Plot No-9, Ramabaug Society, Government Medical College, Anantwadi, Bhavnagar, Gujarat - 364 001, India. E-mail: priteshgandhi2@gmail.com A study on cardiac autonomic modulation during pregnancy by non-invasive heart rate variability measurement Purpose: Remarkable and uncontrollable changes with modification during pregnancy are connected with the autonomic control and consequently with the heart rate variability (HRV). Heart rate variability is a sum of different mechanisms and if pregnancy is a state of change, these modifications could be extracted from HRV analysis. Objective: To assess the effect of pregnancy on heart rate variability among pregnant mothers during first trimester of pregnancy and third trimester of pregnancy. Materials and Methods: HRV was measured for 5 minutes of continuous recording of electrocardiogram (ECG) lead II, using windows based HRV analysis system variowin-HR after obtaining permission from the Institutional Review Board of Government Medical College, Bhavnagar and written consent from 30 pregnant subjects and 30 non-pregnant control subjects at autonomic function lab, Dept of Physiology, Bhavnagar. Result: Frequency domain parameters, very low frequency (VLF), low frequency (LF), high frequency (HF) and HF normalized unit (nu) were significantly decreased and LF (nu) and LF/HF significantly increased in pregnant subject in 3 rd trimester as compared to their 1 st trimester of pregnancy. Time Domain parameters like SDNN, RMSSD, SDSD, NN50 count, pNN50, SD1/SD2, triangular HRV index and average R-R interval were significantly decreased during 3 rd trimester of pregnancy. Conclusion: The inhibition of resting parasympathetic activity or vagal blockage and an increment of the sympathetic modulation during the 3 rd third trimester of gestation in pregnancy as compared to their 1 st trimester and healthy non-pregnant subjects. Sympathovagal imbalance and abnormally low HRV may more pronounce during later stage of normal pregnancy. Key words: Autonomic function test, gestation, heart rate variability, pregnancy Original Article INTRODUCTION The last three decades have witnessed the recognition of a significant relationship between the autonomic nervous system and cardiovascular mortality, including sudden cardiac death. [1] Heart rate variability (HRV) is a non-invasive, easy and economical technique to assess the status of autonomic nervous regulation of cardio vascular system. Heart with a stable and regular heart beat periodically is now considered as the marker for a poor prognostic for longevity. [2] HRV studies enhance understanding of physiological phenomenon of heart activity especially during pregnancy. The changes in the function of every regulatory system during pregnancy are initiated by ovarian and placental hormones in the first trimester, but may also be modified by placental and fetal endocrine factors as gestational age advances. Pregnancy-induced effects on cardiovascular function are increases in heart rate (HR), stroke volume (SV), and cardiac output. [3,4] These changes result from the interactive effects of a primary reduction in peripheral vascular resistance, [5] cardiac autonomic modulation and baroreflex function that lead to a higher resting heart rate. It is well established that high-frequency (HF) power (0.15-0.40 Hz) of HRV is mediated by parasympathetic nervous system (PNS) modulation and respiratory sinus arrhythmia, [6-8] whereas low-frequency (LF) power (0.03-0.15 Hz) reflects both sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) autonomic influences. [8,9] The ratio of low-frequency power to high-frequency power (LF/HF) has been used to reflect cardiac sympathetic modulation (SNS Abstract Access this article online Website: www.ijmedph.org DOI: 10.4103/2230-8598.144131 Quick response code: