A study of cardiovascular autonomic function in normal pregnancy

Objective: The present study was designed to evaluate the physiological responses to noninvasive cardiovascular autonomic function tests in normal pregnancy and compare them with non- pregnant controls. Materials and Methods: The study population comprised of 90 apparently healthy, pregnant women divided equally into three groups based on their period of gestation and 30 otherwise healthy, non-pregnant women as controls. The standard autonomic function tests based on cardiovascular reflexes, including heart rate response tests and blood pressure response tests were performed. Result: It was observed that variability of mean between and within all the population groups and controls was significantly different. Multiple comparison analysis revealed a significantly lower Deep Breathing Difference in pregnant subjects, significant difference in Valsalva Ratio in third trimester group, a significantly lower Postural Tachycardia Index only during last trimester and a significantly higher fall in systolic blood pressure on standing only during 1st trimester. A significantly lower alteration in diastolic blood pressure during isometric handgrip in later trimesters and a significant increase in overall cardiovascular autonomic score between and within all groups were also observed. Conclusion: The observations serve to corroborate that the cardiovascular indices in pregnant women are significantly altered in comparison to non-pregnant women, thus highlighting the importance of cardiovascular monitoring during pregnancy. The study also helped to reaffirm the efficacy of simple cardiovascular reflex tests in research on pregnancy physiology.