Many doctors recommend that women in labor sit upright or walk to speed things along. But a randomized trial suggests the best bet may be to lie on your side.

British researchers randomly assigned 3,093 first-time mothers with a low-dose epidural in the second stage of labor to either an upright position (walking, kneeling, standing or sitting up straight) or to a lying-down position (up to 30 degrees inclination).

All the women had singleton pregnancies, and about 40 percent had their labor induced. The groups were similar in other health and behavioral characteristics.

The study, in BMJ, found that 35.2 percent of women in the upright group achieved a vaginal delivery without the use of forceps, compared with 41.1 percent in the group lying down — a statistically significant increase. (Forceps are more commonly used in Britain than in the United States.)

Labor was slightly shorter in the women lying down, but there were no differences in other outcomes, including cesarean section or other medical interventions.

“We’d recommend that women try to lie down on their sides when the cervix is fully dilated,” said the lead author, Dr. Peter Brocklehurst, a professor of women’s health at the University of Birmingham in England. “If they can’t, that’s fine. But most women want to have a spontaneous vaginal birth, so most will try to lie on their side if that gives them a better chance.”