Acute fetal behavioral response to prenatal yoga: A single blinded, randomized controlled trial

Yoga is becoming a popular exercise to perform in pregnancy. A recent literature review on prenatal yoga noted a reduction in some pregnancy complications in those who practiced yoga; to date there is no evidence on fetal response after yoga. We aimed to characterize the acute changes in maternal and fetal response to prenatal yoga exercises using common standardized tests to assess the well-being of the maternal-fetal unit.;We conducted a single blinded, randomized controlled trial. Uncomplicated pregnancies between 28 0/7 to 36 6/7 weeks with a non-anomalous singleton fetus of women who did not smoke, use narcotics, or have prior experience with yoga were included. A computer-generated simple randomization sequence with a 1:1 allocation ratio was used to randomize participants into the yoga or control group. The yoga group participated in a one-time, one-hour yoga class with a certified instructor who taught a predetermined yoga sequence. In the control group, each participant attended a one-time, one-hour PowerPoint presentation by an obstetrician on American Congress of Obstetricians and Gynecologists recommendations for exercise, nutrition, and obesity in pregnancy. All participants underwent pre and post intervention testing which consisted of umbilical and uterine artery Doppler ultrasound, non-stress testing, a biophysical profile, maternal blood pressure and maternal heart rate. A board-certified Maternal-Fetal Medicine specialist, at a different tertiary center, interpreted all non-stress tests and biophysical profile data and was blinded to group assignment and pre or post intervention testing.;The primary outcome was a change in umbilical artery Doppler systolic-to-diastolic ratio. Sample size calculations indicated 19 women per group would be sufficient (alpha = 0.05 power = 80%).;Of the 52 women randomized, 46 (88%) completed the study. There was no clinically significant change in umbilical artery systolic-to-diastolic ratio (p=0.34), pulsatility index (p=0.53), or resistance index (p=0.66) between the two groups before and after intervention. Fetal and maternal heart rate, maternal blood pressure and uterine artery Dopplers remained unchanged over time.;There was no significant change in fetal blood flow acutely after performing yoga for the first time in pregnancy. Yoga can be recommended for low risk women to begin during pregnancy.