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Melissa Boisvenue with her seven-month-old daughter Gracie at home September 17, 2013 in Ottawa.Dave Chan/The Globe and Mail

When Melissa Boisvenue was 30 weeks pregnant, she slipped on ice on her way into work at the Children's Hospital of Eastern Ontario. By that night, the 28-year-old registered nurse from Ottawa began experiencing contractions and bleeding – telltale signs of preterm labour.

Her husband, Nate, rushed her to the hospital, where doctors found her blood was mixing with the baby's. She was hooked up to monitors and given steroids to develop the baby's lungs in case she had to give birth right away.

After a few days her obstetrician sent her home with a strict prescription to stay in bed for all but 15 minutes a day, and, after two weeks, for modified bed rest.

Although Grace Evelyn Boisvenue, now seven months old, was born healthy a week after Boisvenue returned to work at 36 weeks, growing scientific evidence shows that bed rest during pregnancy has no demonstrated benefits – and a number of potential harms.

Two papers published this summer in the journal Obstetrics and Gynecology questioned the usefulness of instructing high-risk pregnant women to rest in bed, whether it's for a few hours a day or 24/7.

In a retrospective study of 646 women with shortened cervix, a major risk factor for preterm birth, women told to restrict their activity were more than twice as likely to give birth early.

An analysis of six scientific reviews involving more than 4,100 patients showed that bed rest wasn't associated with significantly better outcomes with respect to multiple births, reduced fetal growth, miscarriage, or early delivery or pre-eclampsia. Further, while everyone rapidly loses muscle mass and bone density during strict bed rest, the risk of life-threatening blood clots – already a concern during pregnancy – increases sharply when physical activity stops. Lead author Dr. Christina McCall wrote that based on her findings, prescribing bed rest is unethical and violates the Hippocratic principle of "do no harm."

Bed rest can also lead to "psychological distress," said Joanna Nemrava, president of the Canadian Association of Midwives.

"I've seen it be very hard on women who don't have support systems, and particularly women who have other children," she said. "It probably contributes to some of the guilt that they feel, because they actually are realistically unable to comply."

Despite care packages, family support and stacks of Sudoku puzzles, being cooped up took a physical and emotional toll on Boisvenue.

Her thrice-weekly workouts were forgotten along with her Christmas shopping plans and her clean house. She slept poorly, felt "really sore," and while her husband worked days as a business systems analyst, she lay in bed worrying and counting her contractions. More than four in an hour meant a trip back to the hospital.

Despite mounting concerns about bed rest, it remains a common prescription. In a 2008 survey, the most recent data available, 65 per cent of Canadian OB/GYNS and 70 per cent of family doctors said they prescribe bed rest at home for preterm labour. About half of each group rated its effectiveness as "fair" or "poor."

Dr. Michael House, an authority on the physics of the cervix, says while the age-old idea of tipping a woman on her back to relieve pressure exerted by gravity is intuitive, it's also too simplistic.

House, an obstetrics researcher at Tufts Medical Center in Boston, says that along with gravity, the stretching of the uterus as the baby grows, a change in the adhesion of the membranes, and pressure from the baby's head could all upset the balance of forces at work.

At the crux of this issue is the quest for better data. While every maternity-care provider has patients like Boisvenue who seem to benefit from bed rest, translating anecdotes into solid science requires a randomized trial in which high-risk women are assigned either bed rest or a placebo – an ethical minefield.

"You can't really answer the question unless the study is randomized. I don't know who's going to do a randomized trial. I'm not going to do it," House said.

Dr. Ward Murdock, president of the Society of Obstetricians and Gynaecologists of Canada, said while reduced activity is preferable to strict bed rest, the SOGC has no guidelines on the topic because there isn't enough scientific evidence to say whether it's a good idea or not.

Until a study happens, hundreds of Canadian women will rest in bed when they could be at work or with their families.

For Nemrava of the midwives association, that's not good enough.

"We know that bed rest does not help women feel they're doing the best that they can and can really increase their feelings of helplessness and hopelessness and anxiety," she said. "Women don't need to be rescued or protected, they need to be given frank information about what we know and don't know."

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