NEW YORK - Modern mothers-to-be are turning to the 4,000-year-old practice of yoga to put mind over pregnancy matters as they strengthen their bodies for the road ahead.

"There's a level of comport and presence women cultivate when they're practicing regularly through their pregnancies, so the changes that come are not going to shake them," Elena Brower, a New York City-based yoga instructor said in an interview.

The founder of the Virayoga studio in Manhattan, Brower has worked with celebrities Gwyneth Paltrow and Christie Turlington Burns during their pregnancies. She also has developed the DVD "Element: Prenatal & Postnatal Yoga."

"It's about teaching women how to safely strengthen their abdominals," said Brower, herself the mother of a toddler. "And strengthening is complemented by learning how to stretch, so that you can be as limber as possible when that baby comes."

Yoga can also help women to get to know themselves a little better.

"You have a level of presence that allows you to ride the wave of the contraction/pain into another place. You don't think intellectually about it. You breathe."

A study of 335 pregnant women in Bangalore, India, found that those who practiced yoga experienced shorter labor, less pregnancy-induced hypertension, and higher birth-weight babies than the control group.

More than 11 million Americans are estimated to do some form of yoga. The name derives from the Sanskrit meaning yoke or union, and the practice strives to unite movement and breath.

Brower cautions that some of the pretzel-like contortions that characterize the practice are not suitable for expectant mothers, even if they are experienced yogis.

"Don't lie on your belly, don't twist. You want to keep the house as big as possible for the baby," she advises. "Do inversions if it feels right."

Dr. Jacques Moritz, Director of Gynecology at St. Luke's-Roosevelt Hospital in New York City, says yoga is a fine idea for pregnant women, as long as they inform their instructors of their condition.

"Yoga is a great relaxing exercise. It's good for flexibility, it limbers people up," he said. "Part of the process of having a baby is opening up your pelvis. Yoga is one of the good ways to do that. It strengthens your core muscles and pelvic diaphragm."

Moritz, who is featured in the 2008 documentary film "The Business of Being Born," said it also helps the back pain that nearly all women get during pregnancy.

Post-natal yoga can help new mothers re-tone and strengthen the pelvic floor but Moritz warned they should wait six to eight weeks after the birth before resuming yoga.

"You can't do something if you're still fatigued," he explained. "Most women are still breast-feeding on demand every three hours. So the last thing on their mind is exercise."

Then there's the challenge of losing that postpartum weight. The average woman puts on about 30 pounds of it during pregnancy.

Moritz is familiar with those celebrity supermoms who seem to drop their baby weight in the time it takes the rest of us to complete a sun salutation.

"For celebrity clients it's all about getting back in shape immediately," he said. "Most of them are doing yoga and Pilates."