Effect of integrated yoga on stress and heart rate variability in pregnant women

OBJECTIVE: To study the effect of integrated yoga practice and guided yogic relaxation on both perceived stress and measured autonomic response in healthy pregnant women. METHOD: The 122 healthy women recruited between the 18th and 20th week of pregnancy at prenatal clinics in Bangalore, India, were randomized to practicing yoga and deep relaxation or standard prenatal exercises 1-hour daily. The results for the 45 participants per group who completed the study were evaluated by repeated measures analysis of variance. RESULTS: Perceived stress decreased by 31.57% in the yoga group and increased by 6.60% in the control group (P=0.001). During a guided relaxation period in the yoga group, compared with values obtained before a practice session, the high-frequency band of the heart rate variability spectrum (parasympathetic) increased by 64% in the 20th week and by 150% in the 36th week, and both the low-frequency band (sympathetic), and the low-frequency to high-frequency ratio were concomitantly reduced (P<0.001 between the 2 groups). Moreover, the low-frequency band remained decreased after deep relaxation in the 36th week in the yoga group. CONCLUSION: Yoga reduces perceived stress and improves adaptive autonomic response to stress in healthy pregnant women.