Many pregnant women are told to avoid certain yoga poses as their pregnancy progresses. This may not be necessary, according to a small study.
Yoga can help pregnant women maintain flexibility and muscle tone and develop breathing techniques that may be useful during labor. But women are often warned not to use postures that involve lying on their backs, such as those known as the "happy baby pose" or "corpse pose," or postures that have them partially upside down, such as "downward facing dog. " These poses could reduce blood circulation to the fetus and possibly lead to a spike in fetal heart rate.
But is this caution needed? To see, researchers monitored fetal heart rates while 25 healthy women in the final weeks of pregnancy tried 26 common yoga poses. The women had no history of high blood pressure or other complications, and none had any medical conditions that required them to avoid exercise.
Ten of the women did yoga regularly, eight were familiar with yoga, and seven were not familiar with it. The women had a one-on-one yoga session with a certified yoga instructor. None of the poses used involved lying on the stomach or becoming completely inverted, such as a hand-stand. The women had stress tests before going through the poses and again afterward.
The fetal heart rates remained normal through all of the poses. None of the women reported decreased fetal movement, contractions, fluid leakage, or vaginal bleeding in the next 24, according to the study.
These results are limited by the small size of the study and by the overall healthiness of the women enrolled in the study, who were all of normal weight. The study was published in the journal Obstetrics & Gynecology.
A different study, reported in the American Journal of Obstetrics and Gynecology, involved 52 pregnant women who had never tried yoga. They were randomly assigned to either participate in a one-time, one-hour yoga class, or to attend a one-time, one-hour lecture about exercise, nutrition, and obesity in pregnancy.
There was no significant change in fetal blood flow immediately after the women did yoga. The study concluded that healthy women could safely begin yoga during pregnancy.