A study done at Brigham and Women's Hospital in Boston, Mass, showed that receiving an epidural analgesic during labor increases the risk of the fetus assuming a face-up position. Instead of the face-up position sparking the need for an epidural, research shows that it is more probable that the epidural causes the repositioning.
Researchers used ultrasound data from 1562 women during labor and delivery, 92% of whom received epidurals. They noted that fetal position changes were common during labor. At the initial examination, ~49% of fetuses were facing sideways, 27% facing down, and 24% facing up. At delivery, the rates were 8%, 80%, and 12%, respectively.
In epidural patients, 12.9% of fetuses were delivered face-up, but only 3.3% in nonepidural patients.