Oct. 19, 2005 -- Pregnant women with uncontrolled high blood pressure may be put on bed rest for days, weeks, or even months, but it is not clear if the practice improves birth outcomes, a newly published review shows.
Researchers concluded that there is not enough clinical evidence to conclude that bed rest is or is not useful for moderate to severe hypertension in pregnancy.
"Despite the fact that bed rest is recommended quite often in clinical practice, very few well- designed trials have evaluated its effectiveness," researcher Shireen Meher, MDBS, tells WebMD.
"Until there is good evidence to show that bed rest is beneficial, it should not be recommended routinely in clinical practice for pregnant women with hypertension."
Major Cause of Death
While some women enter pregnancy with high blood pressure, others develop hypertension after becoming pregnant or become hypertensive as a result of a potentially serious complication of pregnancy known as preeclampsia.
Preeclampsia occurs in about 5% of pregnancies, usually diagnosed after the 20th week. In addition to high blood pressure (140/90 or greater in a woman with previously normal blood pressure), the condition is characterized by protein in the urine.
In its most severe form (blood pressure of 160/110 or higher), preeclampsia can threaten the life of the mother and her baby. Women with the condition must be closely monitored, and bed rest is often recommended. But the only known cure is delivery of the baby.
Preeclampsia and other high blood pressure disorders are the major cause of pregnancy-related death.
Do Risks Outweigh Benefits?
Meher and colleagues found only four well-designed clinical trials assessing bed rest in pregnant women with high blood pressure. Two of the trials compared strict bed rest in a hospital setting with less restrictive bed rest in women with preeclampsia. The other two examined whether limited bed rest in the hospital was useful for preventing progression to preeclampsia or severe hypertension in pregnant women with moderately high blood pressure.
One small study did suggest that some bed rest reduced the risk of preterm birth, but none convincingly showed an advantage for bed rest in pregnancies complicated by hypertension, the authors concluded.
The researchers were part of the Cochrane Collaborative, an international, nonprofit organization that conducts systematic reviews of current medical practices.
Meher points out that in addition to having no obvious benefit, there are potential risks and clear disadvantages to putting pregnant woman on bed rest.
Long-term immobility is associated with an increased risk of blood clots, and involuntary bed rest is likely to add stress to an already stressful pregnancy. And women who work suffer economically, Meher says.
"Because of these potential negative effects, I think there should be better evidence before bed rest is recommended to women," she says.
Pennsylvania ob-gyn John T. Repke, MD, agrees that there is a paucity of clinical evidence showing that bed rest improves pregnancy outcomes in women with hypertension. But he adds that bed rest clearly reduces daily fluctuations in blood pressure, which may have an impact on outcomes.
"The bottom line is that we still recommend bed rest to many, many women who have blood pressure disorders or mild preeclampsia, to flatten out blood pressure throughout the day," he says.
"It makes sense that this should make a difference, but we don't know with certainty that it will change outcomes one iota."
Repke says he is careful to explain this to his bed-rest patients so that they don't feel that they are to blame if something bad happens.
He is chairman of the department of obstetrics and gynecology at Penn State College of Medicine-Milton S. Hershey Medical Center and is the former president of the North American Society for the Study of Hypertension in Pregnancy.
"Human nature being what it is, a woman who doesn't comply fully may feel guilty when there is an unfortunate outcome," he says. "We don't want patients to think it was their fault because they got up and did the ironing or went to the bathroom."