Pregnant women can encourage life long health in their children by being relaxed during pregnancy. When women are stressed, their cortisol levels increase, which can have detrimental effects on the fetus, priming them to a lifelong exaggerated response to stress, and perhaps a susceptibility to addictive behaviour patterns to diffuse the stress response. Yoga and meditation are effective tools in pregnancy to decrease the stress response, protecting mother and child.
A 2009 study published in the Int J Gynaecol Obstet Mar;104(3) explored the effect of yoga on stress and heart rate variability in pregnant women. One hundred and twenty-two healthy women between the 18th and 20th week of pregnancy in Bangalore, India, were randomized to practicing yoga and deep relaxation or standard prenatal exercises 1-hour daily. The results revealed that perceived stress decreased by 31.57% in the yoga group and increased by 6.60% in the control group. 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. The study concluded that yoga reduces perceived stress and improves adaptive autonomic response to stress in healthy pregnant women.
The positive effects on society as a whole would be enormous if fetuses experienced a less stressful environment in the womb, resulting in a less dramatic response to stress throughout their lives..