Against Bed Rest: There's No Proof That It Works.

Pregnancy by the Numbers
Aug. 19 2013 8:00 AM

Against Bed Rest   

bed_rest
More stressful than it looks

Photo by Eternalfeelings/Shutterstock

As many as 20 percent of women are prescribed bed rest for a period of time during their pregnancies, ranging from a few days to multiple months. Usually the concern is threatened premature labor, which could result from a specific condition or occur without warning.

Emily Oster Emily Oster

Emily Oster is an associate professor of economics at the University of Chicago Booth School. Her book is Expecting Better: Why the Conventional Pregnancy Wisdom Is Wrong. Follow her on Twitter.

So why bed rest? Well, it seems logical—surely laying down and not jostling so much is a good idea! And if you know someone who has been on bed rest and went on to have a healthy, full-term delivery, it may look like it worked. Many women who are put on bed rest go on to have their babies at a normal time. 

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But, and I cannot stress this enough, that is not evidence that it works. We don’t know what would have happened if those women engaged in normal activities. In fact, there is no compelling evidence to suggest that bed rest is effective at preventing preterm labor.

This is most conclusively demonstrated by randomized studies—the gold standard in medical evidence—where some women are selected to be on bed rest and others are selected not to be. Because the selection is random, we can be confident in attributing any differences across the groups to bed rest.

Consider one study of 1200 pregnant women—400 of them were put on bed rest, and 800 were not. In the end, 7.9 percent of the bed rest group had premature babies, versus 8.5 percent of the non-bed-rest group, a difference that was so small that it could have been due to chance. Other randomized evidence on twin and triplet pregnancies (which often result in bed rest prescriptions) demonstrates the same thing. This review article from 2011 says it bluntly: “There are no complications of pregnancy for which there are demonstrated benefits of bed rest.”

So, what should we do with this information? Well, we need more randomized evidence, with larger studies. But, at the moment, we simply have no evidence suggesting bed rest works in improving outcomes for babies, so we should stop sending pregnant women to their beds.

You might prefer to think “better safe than sorry,” but bed rest actually has some significant negative consequences. Full bed rest is defined as one to two hours of activity per day, with the rest of the time spent in bed. No work, no running after your toddler, no setting up the baby's room, no making dinner, no exercise, no nothing. This has serious downsides for your family and, for women who work, their jobs. Studies cite financial strain on families when women are put on bed rest, even if they don’t work, because of the need to get someone else to help around the house.

Plus, there are actually medical risks to bed rest—bone loss, muscle atrophy, weight loss and, in some studies, decreased infant birth weight.  There is some evidence to suggest that bed rest increases the risk of blood clots (to avoid this, women on bed rest sometimes wear compression socks).

Usually when we consider a medical treatment with no demonstrated benefits and large demonstrated risks, we conclude that it’s a bad idea. In fact, that’s the strong consensus in the medical literature. Last year the American Congress of Obstetricians and Gynecologists—the official source for pregnancy rules and regulations—issued a bulletin suggesting that bed rest was not, in fact, a recommended treatment for premature labor.

And, even more surprising, many doctors seem to know this is a waste of time. A 2009 article that reported on a survey of practicing OBs showed that more than half of them say that bed rest has “no” or “minimal” benefit.  And yet: 90 percent of these doctors reported prescribing bed rest!

It would seem that this is one of those areas where the conventional recommendation has hung on despite evidence suggesting it's not just ineffective but damaging. There may be unusual situations in which bed rest is a good idea, but the medical literature hasn’t found any of them. So what should you do if your doctor suggests bed rest? You should almost certainly question him or her. Do they really think it will help? It may be hard to push back if they insist you rest, but you should at least be sure they are aware of the evidence to the contrary.