Hey would-be moms, eager to pick up the pace of your delivery? One piece of advice: don't lie down.

Researchers report in today's Cochrane Review that women who knelt, sat or walked around during the early stages of labor instead of lying in bed sliced as much as an hour off of the birthing process. The would-be moms were also less likely to need an epidural (a painkiller injected into the spine). The conclusions are based on an analysis of 21 studies involving 3,706 women.

Women in industrialized countries tend to lie in bed during labor, possibly because that position makes it easier for health-care workers to monitor the progression of labor as well as the baby's health, according to the review. But by lying down, a pregnant woman is putting the weight of her belly on blood vessels in the abdomen. That pressure may weaken the strength of her contractions, which could slow the dilation of her vagina and the descent of the baby through the birth canal, the authors write.

Why might positioning reduce a woman's need for an epidural? Moving around may distract a woman from the pain of contractions, according to the review, or increase her sense of control. Both of those factors may decrease her need for pain medication, they say.

"In most developing countries, women stand up or walk around as they wish during the early stages of birth with no ill effects," study co-author Annemarie Lawrence, a research midwife at the Institute of Women's and Children's Health at Townsville Hospital in Queensland, Australia, said in a statement. "This review demonstrates that there is some benefit and no risk to being upright and or mobile during first-stage labor. We would recommend that women are encouraged to use whichever positions they find most comfortable, but are specifically advised to avoid lying flat."

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